CN100590877C - Film semiconductor device and manufacturing method thereof - Google Patents
Film semiconductor device and manufacturing method thereof Download PDFInfo
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- CN100590877C CN100590877C CN200610071008A CN200610071008A CN100590877C CN 100590877 C CN100590877 C CN 100590877C CN 200610071008 A CN200610071008 A CN 200610071008A CN 200610071008 A CN200610071008 A CN 200610071008A CN 100590877 C CN100590877 C CN 100590877C
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Images
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- Thin Film Transistor (AREA)
- Liquid Crystal (AREA)
- Liquid Crystal Display Device Control (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Control Of El Displays (AREA)
- Manipulation Of Pulses (AREA)
Abstract
This invention provides a thin film semiconductor device and its manufacturing method which can form n-channel thin film transistors (TFTs) and p-channel TFTs suitable for circuit characteristics on apolycrystalline silicon film without complicating the manufacturing processes. When n-channel thin film transistors (TFTs) and p-channel TFTs are formed on a polycrystalline silicon film 3 formed ona glass substrate 1, a process is included in which p-dopant or n-dopant is introduced to the channel regions of some n-channel TFTs and those of some p-channel TFTs at the same time. In one channel doping operation, a set of low-VT and high-VT p-channel TFTs and a set of low-VT and high-VT n-channel TFTs can be formed. This method is used for forming high-VT TFTs which can reduce the off-currentfor logics and switch circuits, and for forming low-VT TFTs which can increase the dynamic range for analog circuits, thus improving the performance of a thin film semiconductor device.
Description
The application be submitted on September 10th, 2003, application number be 03158436.5, denomination of invention divides an application for the application of " thin film semiconductor device and manufacture method thereof ".
Technical field
The present invention relates to thin film semiconductor device and manufacture method thereof, particularly adopt the different thin-film transistor (TFT) of threshold voltage (VT), to comprise thin film semiconductor device and the manufacture method thereof that analog circuit portion and switch constitute at least.
Background technology
As the monitor of mobile terminal device such as mobile phone, mobile device or notebook-sized personal computer etc., used and compared with CRT with thin and gently be image display devices such as the liquid crystal indicator of feature or organic EL display.These liquid crystal indicators or organic EL display applied film formation technology form on insulating properties substrates such as glass substrate has the display part that is arranged in rectangular pixel, utilize drive circuits such as outer attached gate driver, data driver that each pixel is applied with showing corresponding signal and control the luminous of the direction of orientation of liquid crystal or organic EL, to carry out the image demonstration.In recent years, along with film forms development of technology, can form a part of drive circuit with the TFT circuit that uses polysilicon being to form TFT with polysilicon on the same substrate with display part.
In mobile terminal device, it is important trying to achieve miniaturization, low power consumption and high performance, accompanies therewith, now seeks miniaturization and low power consumption over against image display device.As the method that realizes the image display device miniaturization, can be by on glass substrate etc., being integrally formed display part and drive circuit, reducing the quantity of outer attached parts, thereby realize miniaturization.In addition, by being integrally formed display part and drive circuit, can also reducing by the wiring of outer connection resistance, outside attached connecting terminal the when attached load capacity that causes such as circuitous, thereby realize low power consumption.In addition, in recent years, image display device requires high-fineness, distinct demonstration, thereby the demand of the active matrix type display that forms each pixel is independently being increased.Active matrix type display is provided with switch element for each pixel, signal corresponding that utilization is provided by drive circuit and the signal that switch element is controlled with image, when switch element is ON state (conducting state), each pixel is applied the signal corresponding with image, to show.In addition, when being integrally formed active array type display part and drive circuit on glass substrate etc., can make the switch element (TFT) of each pixel simultaneously and the TFT of the drive circuit that on same substrate, forms.
Though above-mentioned TFT adopts n channel-type, 2 kinds of TFT of p channel-type to constitute, but in general owing to tend to constitute the polysilicon film n typeization of active layer, and n channel-type TFT some exhausts slightly, so driving electric increases relatively, OFF state (off state) electric current increases.Image display device especially for the image display device of mobile terminal device, in order to reduce power consumption, requires off-state current low to switching TFT at least, and therefore, the channel region to n channel-type TFT when making TFT mixes, so that VT is controlled.
This channel doping carries out together to the channel region of a plurality of TFT usually, thus inject a plurality of TFT dopant dosage about equally, but also can in once mixing, change the dosage of each TFT.For example, open the spy and to disclose in the flat 8-264798 communique by each district being changed the thickness of the controlling diaphragm (silicon oxide film) be used for controlled doping agent injection rate, mix from it, make at the thin part dosage of controlling diaphragm to increase, the method that reduces at the part dosage of control thickness.
Here, varied with the circuit that TFT forms, the circuit that existing logical circuit etc. utilize 2 value level of low level and high level to carry out digital processing also has amplifying circuit etc. to carry out handling the circuit of the simulation process of continuous quantity.Also have, switch is switched conductive and a non-conduction element between 2 terminals, and it can cut off 2 electric currents between the terminal, or retrains (preservation) electric charge with capacitor bank together, or play other effects, can insert in logical circuit or the analog circuit according to the purpose of using and use.
But, the performance difference of the TFT of these different types of circuit requirements.For example, be used for the TFT of logical circuit or switch, must sufficient current driving ability be arranged in ON state, and not circulate at off-state current.Particularly in strong request occasion low in energy consumption, off-state leakage current is very for a short time to be very important.At this moment, threshold voltage will be set highlyer.On the other hand, be used for the occasion of analog circuit at TFT, the TFT that flows through the circuit part of no-load current often is ON state, and the work of analog circuit can be worth big value and leakage current very accurately controlled very important from little by means of the control voltage of TFT.
When off-state leakage current is big, even at the out-of-work state of circuit, also consume electric power because of leakage current, be the drive circuit of mobile device of one of important performance particularly concerning life-span of battery, this is an important problem very, in addition, since the requirement of energy savings recently, the stand-by electric when power consumption the when device outside the mobile device also is sought after reducing work and reduction quit work.Because this requirement, the TFT that uses in the existing circuit all controls threshold voltage VT higher, so that off-state leakage current very little (for example below 1pA).
But, in existing channel doping, because the channel region of all n channel-types (or p channel-type) TFT is mixed together, so for example when n channel-type TFT is carried out channel doping, the VT Be Controlled of all n channel-type TFT gets identical.Therefore, in order to suppress off-state leakage current littler with the threshold voltage settings of TFT when high, the TFT conducting region of supply voltage scope narrows down, the upper limit of TFT current driving ability descends, thereby the operating rate that has produced circuit descends, perhaps the dynamic range of analog circuit (output voltage range of supply voltage scope relatively) other problem such as narrow down.
In addition, during the method for mixing with a side to n channel-type or p channel-type, have only the leakage current of the TFT of side's channel-type to change with the variable quantity of gate source voltage, therefore, the symmetry of the VT of the VT of n channel-type TFT and p channel-type TFT is destroyed, for example, and in the occasion that forms cmos circuit, its operating rate is determined by the bad TFT of characteristic, thereby has produced the problem that can not obtain good circuit characteristic.
In order to suppress the symmetry-violating of above-mentioned VT, the method that existence is mixed respectively to the both sides of n channel-type or p channel-type, but when using the method, because same channel-type TFT has identical VT, so can not solve operating rate, the dynamic range variation of analog circuit when improving VT, and the problem that the off-state current of logic OR switching circuit increases when reducing VT, also have, because of the error in the manufacturings such as doping accuracy, the symmetry of VT can not be strictly kept, thereby the harmonious good film semiconductor device of VT can not be made.In addition, also exist because of carrying out the problem of channel doping complex procedures several times.Also have, promptly use the spy to open the described method of flat 8-264798 communique and carry out this channel doping, also must at least respectively carry out channel doping 1 time, still can not solve the problem of complex procedures n channel-type TFT and p channel-type TFT.
These problems are not limited to the circuit that uses in image display devices such as liquid crystal indicator, organic EL display, also be the problem that has with the polysilicon film all circuit that are the n channel-type TFT of active layer and p channel-type TFT.
Japanese kokai publication hei 8-264798 communique (4-7 page or leaf, the 5th figure)
Non-patent literature 1
Write former centre: " MOS integrated circuit basis ", super LSI goes into 5, the 64 pages of gate series, modern science publishing house, distribution in Mays 30 in 1992
Summary of the invention
In view of the above problems, main purpose of the present invention is, provide can be to form n channel-type TFT and p channel-type TFT, do not increase power consumption and improve the thin film semiconductor device and the manufacture method thereof of analog circuit performance with the VT that is fit to various circuit with complicated step.In addition, provide not only suppressed the current sinking increase, but also the circuit that has improved characteristics such as dynamic range also be one of purpose of the present invention.
For achieving the above object, the thin film semiconductor device of one aspect of the present invention is, at least be provided with on the insulating properties substrate with the polysilicon film is the n channel-type thin-film transistor (TFT) of active layer and the thin film semiconductor device of p channel-type TFT, this device comprises the different multiple TFT of threshold voltage in same channel-type, comprise the TFT that same dopant is introduced channel region with concentration about equally in different channel-types.
The different multiple TFT of above-mentioned threshold voltage of the present invention can be made of the TFT of a kind of dopant that contains P type or N type in channel region and the TFT that does not contain dopant in channel region, perhaps by the TFT of the dopant that contains P type or N type one side in channel region with contain the P type and the TFT of two kinds of dopants of N type constitutes in channel region.
In addition, the circuit of formation thin film semiconductor device of the present invention is best, at least have the analog circuit and the switch that when circuit working, need no-load current, above-mentioned analog circuit constitutes by means of contain the low TFT of threshold voltage among the different multiple TFT of above-mentioned threshold voltage on the current path of above-mentioned no-load current, and above-mentioned switch is made of the high TFT of threshold voltage among the different multiple TFT of above-mentioned threshold voltage.
In addition, above-mentioned analog circuit of the present invention can be to contain above-mentioned switch on the current path of above-mentioned no-load current, the structure that above-mentioned no-load current can be cut off by this switch, about above-mentioned analog circuit, the work of this circuit and best conducting and the cut-out by means of the above-mentioned no-load current that is caused by above-mentioned switch that quit work are controlled.
In addition, the structure of above-mentioned analog circuit of the present invention portion is preferably: when containing the low TFT of above-mentioned threshold voltage on the current path path of the above-mentioned no-load current between each terminal at input terminal, lead-out terminal and power supply terminal, contain above-mentioned switch on this current path path.
In addition, above-mentioned analog circuit of the present invention also can be to contain the low TFT of above-mentioned threshold voltage differential centering at least, contains the differential amplifier circuit of above-mentioned switch on this differential right current path path.
In addition, the circuit part of the display part of display unit of the present invention and this display part of driving is integrally formed on the insulating properties substrate, contains above-mentioned analog circuit portion and switch in foregoing circuit portion.
In addition, image display device of the present invention has circuit part and the display part that is made of the analog circuit portion, logical circuit portion, the switch that use the TFT form to constitute on the polysilicon film on the insulated substrate, above-mentioned analog circuit portion comprises the threshold voltage low TFT of its threshold voltage than the TFT that uses in above-mentioned logical circuit portion.
The power supply of above-mentioned analog circuit of the present invention portion provides through above-mentioned switch, the structure of above-mentioned switch can be made of the identical TFT of its threshold voltage with the TFT that uses in above-mentioned logical circuit portion, also have, the structure of the pixel switch of above-mentioned display part can be made of the identical TFT of its threshold voltage with the TFT that uses in above-mentioned logical circuit portion.
Method of the present invention is the manufacture method that forms the thin film semiconductor device of n channel-type TFT and p channel-type TFT on the insulating properties substrate at least with polysilicon film, and it is included at least a portion channel region of said n channel-type TFT and introduces the operation of P type or N type dopant simultaneously at least a portion channel region of above-mentioned p channel-type TFT.
In addition, method of the present invention is the manufacture method that forms the thin film semiconductor device of n channel-type TFT and p channel-type TFT on the insulating properties substrate at least with polysilicon film, and it comprises: the operation of introducing P type or N type dopant on full surface; And the operation of at least a portion channel region of said n channel-type TFT and at least a portion channel region of above-mentioned p channel-type TFT, introducing above-mentioned N type or above-mentioned P type dopant simultaneously.
Like this, according to said structure of the present invention, manufacturing process that can be complicated, forming on the polysilicon film that is formed on the insulated substrate such as glass controls VT higher, so that the TFT that the off-state current of logical circuit or switch reduces, and control VT lower, so that the operating rate of analog circuit is accelerated, the TFT that dynamic range increases, in addition, about carrying out the TFT of channel doping, owing to n channel-type and p channel-type are introduced same dopant with concentration about equally,, can make TFT with the characteristic that is suitable for various circuit so can keep the symmetry of VT.
According to the present invention, at least be provided with on the insulating properties substrate with the crystal silicon film is the n channel-type thin-film transistor (TFT) of active layer and the thin film semiconductor device of p channel-type TFT, its structure also can be: the TFT of the channel-type of at least one side in n channel-type and the p channel-type comprises the different multiple TFT of threshold voltage, comprises the TFT that same dopant has been introduced channel region with concentration about equally in different channel-types.
The structure of thin film semiconductor device of the present invention also can be included in 2 kinds of TFT that contain dopant in the channel region of above-mentioned TFT and do not contain dopant.
It is of the present invention that to have on the insulating properties substrate with the crystal silicon film be the n channel-type and the p channel-type thin-film transistor of active layer, a plurality of thin-film transistors of the channel-type of at least one side among n channel-type and the p channel-type can be divided into the threshold voltage thin film semiconductor device of different many kinds mutually, its structure also can be: have a part that constitutes the source current path, TFT and at least 1 relative high TFT of threshold voltage that at least 1 threshold voltage that is connected in series is low relatively, the TFT that above-mentioned threshold voltage is high carries out conduction and cut-off control by the control signal of the control terminal that is applied to this TFT.
The effect of invention
According to thin film semiconductor device of the present invention and manufacture method thereof, produced effect as described below.
The 1st effect of the present invention be, can not increase process number and n channel-type and each formation of p channel-type are had the TFT of different VT.
Its reason is: according to the present invention, not to mix when carrying out channel doping in a certain side's of n channel-type TFT or p channel-type TFT zone, but to all or part of of n channel-type TFT, and all or part of of p channel-type TFT mixed together, thereby simultaneously Doped n and p, and also can change its VT by mixing and undoping to same channel-type.
In addition, the 2nd effect of the present invention is the symmetry-violating that can prevent the VT of n channel-type TFT and p channel-type TFT, can make the circuit design optimization.
Its reason is: because the present invention is not the doping of carrying out the doping of n channel-type TFT and p channel-type TFT respectively, but introduce same dopant with same operation with identical concentration, so can keep the symmetry of VT.
In addition, the 3rd effect of the present invention is can easily form to possess logical circuit, the switch that good pass step response is arranged, and the circuit that the analog circuit of good operation speed and dynamic range is arranged.
Its reason is: the present invention has suitably selected needs such as logical circuit, switch to close the TFT of step response and has not needed to close the TFT that the analog circuit of step response is used, the zone of channel doping is carried out in setting, introduce N type or P type dopant according to the characteristic that circuit needs, thereby VT is controlled.
Description of drawings
Fig. 1 is the profile of structure that the thin film semiconductor device of one embodiment of the present invention is shown.
Fig. 2 is the process profile of manufacture method (mixing B) that the thin film semiconductor device of one embodiment of the present invention is shown.
Fig. 3 is the process profile of manufacture method (mixing B) that the thin film semiconductor device of one embodiment of the present invention is shown.
Fig. 4 is the process profile of other manufacture method (mixing P) that the thin film semiconductor device of one embodiment of the present invention is shown.
Fig. 5 is the process profile of other manufacture method that the thin film semiconductor device of one embodiment of the present invention is shown (B and the anti-P of mixing are mixed in full surface).
Fig. 6 is the process profile of other manufacture method that the thin film semiconductor device of one embodiment of the present invention is shown (P and the anti-B of mixing are mixed in full surface).
Fig. 7 is the circuit diagram of structure that the analog circuit of one embodiment of the present invention is shown.
Fig. 8 is the circuit diagram of structure that the differential amplifier circuit of the present invention the 1st embodiment is shown.
Fig. 9 is the circuit diagram of another structure that the differential amplifier circuit of the present invention the 2nd embodiment is shown.
Figure 10 is the circuit diagram of another structure that the differential amplifier circuit of the present invention the 3rd embodiment is shown.
Figure 11 is the circuit diagram of structure that the drive circuit of the present invention the 4th embodiment is shown.
Figure 12 is the figure of structure that the LCD drive circuits of the present invention the 5th embodiment is shown.
Figure 13 is the figure of structure of drive circuit that the organic EL display of the present invention the 5th embodiment is shown.
Figure 14 is the figure of concrete structure that the data driver of the present invention the 5th embodiment is shown.
Figure 15 is the figure of concrete structure that the memory of the present invention the 5th embodiment is shown.
Figure 16 is the circuit diagram of explanation effect of the present invention.
Figure 17 is the figure of circuit structure that the differential amplifier circuit of the present invention the 6th embodiment is shown.
Figure 18 is that the source electrode that the present invention the 7th embodiment is shown is followed the figure of the circuit structure of amplifying circuit.
Figure 19 is the figure of circuit structure that the differential circuit of the present invention the 8th embodiment is shown.
Figure 20 is the figure of circuit structure that the differential circuit of the present invention the 9th embodiment is shown.
Embodiment
A kind of execution mode to the best of implementing thin film semiconductor device of the present invention and manufacture method thereof describes with reference to the accompanying drawings.Set in the explanation of following mode: analog circuit is meant the circuit of handling continuous quantity, is the circuit that working point when steady operation needs no-load current.Logical circuit is meant the circuit of handling high level and low level 2 threshold voltages.Switch is meant the conducting between switching at 2, the element of not conducting.
As explanation in the prior art part, to being formed with the n channel-type TFT that constitutes by polysilicon film and the thin film semiconductor device of p channel-type TFT, for reducing the off-state current of TFT, n channel-type TFT (or p channel-type TFT) has been carried out channel doping, but, when using this method, the TFT of same channel-type has identical VT.So, when suppress very for a short time for off-state leakage current to realize that low-power consumption sets VT when high with TFT, produce the operating rate of analog circuit, the problem that dynamic range degenerates, can not get the problem of good circuit characteristic owing to the symmetry-violating of VT.
On the other hand, on silicon substrate, form circuit when (being called silicon circuit), for example the sense amplifier of memory circuit exists for high-speed response and suppresses leakage current and adopt the example of 2 kinds of VT, has adopted the method etc. of trap potential adjustment being controlled VT according to each circuit.But, because there are back of the body grid in the silicon circuit, thus method such as trap potential control can be utilized, and the TFT to being provided with on insulated substrate just can not utilize this method, can not the applying silicon circuit engineering.
To the thin film semiconductor device that on insulated substrate, forms, for in logical circuit and switch and analog circuit, controlling VT respectively, also carry out the words of channel doping as if TFT respectively and then can control VT respectively same channel-type, yet when using the method, must at least respectively carry out channel doping 1 time to n channel-type TFT and p channel-type TFT, thereby the manufacturing process of thin film semiconductor device becomes complicated, particularly for the device of the cheap of seeking mobile terminal device etc., it is important problem that the price that the operation increase causes rises.
In addition, utilize the spy to open the described method of flat 8-264798 communique, though can in same channel-type, have different VT, but because above-mentioned communique is not to be doped to purpose simultaneously at n channel-type TFT and p channel-type TFT both sides, the cloth line resistance of having considered the grid line of active matrix display devices causes voltage drop, provide and made apart from grid line drive circuit TFT far away more, the method that its VT is more little, so the same with the method for carrying out channel doping respectively, must at least respectively carry out channel doping 1 time to n channel-type TFT and p channel-type TFT.
In addition, during with these methods, n channel-type TFT and p channel-type TFT are carried out channel doping respectively,, can not solve the problem that when constituting cmos circuit etc., can not get the desired circuit characteristic so the symmetry of the VT of each channel-type is destroyed.
In addition, present inventor's aiming is controlled the VT of each circuit, and the off-state current characteristic that particularly is conceived to TFT when analog circuit is worked is unnecessary.That is, except that such must the cutting off the analog circuit of electric current of analog switch, in general because of analog circuit has no-load current to flow through when working, and TFT is in ON state, and the size of off-state leakage current and the service behaviour of analog circuit, power consumption have nothing to do.And on the other hand, the VT of TFT is low more, and the operating rate of analog circuit is fast more, and dynamic range is also wide more.Therefore, for analog circuit, with regard to its work, though the off-state current of TFT a little some increase do not become problem yet, its VT is low more, performance is good more.
Consider the characteristics of this analog circuit, proposed in the part of n channel-type TFT and the part of p channel-type TFT in introduce the method for same dopant simultaneously, thereby do not cause the doping complex procedures and n channel-type TFT and p channel-type TFT control be suitable for the VT of circuit.In addition, using the method for n channel-type TFT and p channel-type TFT being introduced different dopant, to control the method for VT be the new method that the present inventor proposes and the TFT of different channel-types is introduced same dopant all the time.
Below with reference to Fig. 1 to Fig. 6 the structure and the manufacture method thereof of the thin film semiconductor device of implementing best mode of the present invention are described.In Fig. 1 to Fig. 6, form n channel-type TFT that VT has nothing in common with each other and the situation of p channel-type TFT (amounting to 4 TFT) though show on the insulating properties substrate, but the invention is not restricted to the structure among the figure, can be applied to n channel-type TFT and p channel-type TFT and mix the structure that exists, is suitable for a plurality of a kind of channel-types at least.
As shown in Figure 1, the thin film semiconductor device of implementing a preferred forms of the present invention is on the polysilicon film 3 that is formed at through primary coat coating 2 on the insulating properties substrates 1 such as glass, plastics, formation has low p channel-type TFT (to call low VT-p type TFT (1) in the following text) and the high n channel-type TFT (to call high VT-n type TFT (4) in the following text) of VT of VT that has introduced B (boron) channel region with roughly the same concentration, and high p channel-type TFT (to call high VT-p type TFT (2) in the following text) and the low n channel-type TFT (to call low VT-n type TFT (3) in the following text) of VT of plain VT.That is, it is characterized in that not only different channel-types has also been formed the different TFT of VT to same channel-type.In the superincumbent narration, so-called high VT or low VT are the magnitude relationship of the absolute value of expression current potential.With reference to the process profile of Fig. 2 and Fig. 3, the manufacture method of the thin film semiconductor device of this structure is described.
At first, shown in Fig. 2 (a), the silicon oxide film (SiOx) of the formation primary coat coating 2 of the about 30nm of formation thickness on insulating properties substrates 1 such as glass, plastics such as usefulness LPCVD (decompression CVD) method, PCVD (plasma CVD) method, sputtering method, silicon nitride film (SiNx) etc.This primary coat coating 2 is provided with to the active layer diffusion from insulating properties substrate 1 for preventing impurity, is not to be provided with in the unquestioned occasion of the influence of impurity.Afterwards, form amorphous silicon (hereinafter to be referred as a-Si) the film 3a of the formation active layer of the about 20nm～100nm of thickness with LPCVD method, PCVD method, sputtering method etc.In occasion, carry out dehydrogenation after the film forming and handle with the PCVD method.
Then, shown in Fig. 2 (b), be formed on a-Si film 3a with photoetching process and carry out the resist figure 10a that doped regions is provided with opening, carry out channel doping with ion implantation or ion doping method.Here, in the manufacture method of existing thin film semiconductor device, whole (for example 2 n channel-type TFT on the right side of Fig. 2 (a)) to same channel-type TFT mix, and in the present invention, for VT, selectively only at least a portion (the n channel-type TFT on right side among the figure) of n channel-type TFT and at least a portion of p channel-type TFT (left side is p channel-type TFT among the figure) B that mixed (boron) by 1 mix control n channel-type and p channel-type both sides.With the dopant dosage of this ion implantation or the introducing of ion doping method, though become with the VT that will set,, usually at 2E+11～5E+12/cm
2Scope in be advisable.
In addition, here, in order to narrate the situation that forms above-mentioned 4 kinds of TFT simultaneously, n channel-type TFT and p channel-type TFT both are provided with TFT and the plain TFT that mixes B, but, to the occasion of the different TFT of the square one-tenth VT of n channel-type TFT and p channel-type TFT, also can be partly mix B only to this channel-type.In addition, the TFT that VT is different has been divided into high TFT and low these the 2 kinds of TFT of TFT of VT of VT in the manner, still, also VT can be divided into more than 3 kinds.At this moment, just passable as long as add the different doping operation of dopant species, dosage.
Afterwards, shown in Fig. 2 (c), the part of the part of n channel-type TFT and p channel-type TFT having been carried out the a-Si film 3a annealing (ELA) of mixing, make its crystallization, form polysilicon film 3 with non-doped region 8 and B doped region 9 with excimer laser.
Then, shown in Fig. 2 (d), with photoetching process polysilicon film 3 is etched into the island figure after, shown in Fig. 2 (e), form silicon oxide films as gate insulating film 4 with LPCVD method, PCVD method, sputtering method etc.Though the thickness of this gate insulating film 4 is with the characteristic of TFT such as supply voltage, VT and specification and different, usually to be advisable in the scope about 30nm～200nm.Afterwards, with electric conducting materials such as depositing metal, silicon, silicide such as PCVD method, sputtering methods, to the electric conducting material composition, form gate electrode 5 with photoetching process.
Then, shown in Fig. 3 (a), cover p channel-type TFT with resist figure 10b and form the district, with gate electrode 5 as mask, to n channel-type TFT doping P (phosphorus), then, cover n channel-type TFT with resist figure 10c and form the district, similarly with gate electrode 5 as mask to p channel-type TFT doping B, thereby formation source/drain region.In addition, the order that n channel-type TFT mixes and p channel-type TFT mixes is arbitrarily, also can carry out conversely.
Here, form the occasion of LDD (lightly doped drain) structure in the reliability decrease near the device of the high electric field region the anti-leak-stopping, after utilizing resist to inject dopant grid are compensated, as mask, injection P in low concentration ground activates then with gate electrode 5.As the method that activates, except that the hot activation that traditional type is arranged, utilize the laser active of laser, the RTA (rapid thermal annealing) of also useful light, high temperature N2 etc., selection is suitable for the isostructural activation technology of grid metal most.
Then, shown in Fig. 3 (c), after carrying out the hydrogen plasma processing, silicon oxide deposition film, silicon nitride film etc. form contact hole as interlayer dielectric 6 in grid and source/leakage, form metal as electrode 7, carry out electrode wiring.As this metal, use Al usually.Then, though not shown, the passivating film of formation silicon nitride film etc. forms the pad contact hole, forms thin film semiconductor device.
Like this, in the present invention,, simultaneously a part of p channel-type TFT is formed the district B that also mixes, can not increase operation ground and in same channel-type, make 2 kinds of different TFT of VT by the time to the part doping B of n channel-type.In addition, owing to, introduced same dopant (B) with concentration about equally, so can guarantee the symmetry of VT to hanging down the channel region of VT-n type TFT and high VT-p type TFT.
In the above description, though narrated basically by p channel-type TFT being utilized method by means of the VT of B control n channel-type TFT, control the method for the VT of n, p, but, use additive method, with same consideration method, also can be formed in the TFT that has 2 kinds of VT in the same channel-type to the method for VT of control n, p.For example, as shown in Figure 4, be substituted in the B that mixes in the operation of Fig. 2 (b), the resist figure 10a of the TFT (high VT-p type TFT and low VT-n type TFT) of central authorities is exposed in formation, the method that P is mixed in utilization also can improve the VT of the p channel-type TFT that mixes P, reduce the VT of the n channel-type TFT that mixes P, make the TFT that two kinds of channel-types of n, p is all had 2 kinds of VT.
In addition, compare,, utilize anti-method of mixing the films of opposite conductivity dopant also can all make TFT for two kinds n, p with 2 kinds of VT though increased the operation of mixing together with these methods.For example, also can be as shown in Figure 5, be substituted in the operation of Fig. 2 (b) 2 TFT doping B to two ends, employing is after B is mixed on full surface (to two kinds of n, p) (Fig. 5 (a)), the resist figure 10a of the TFT (high VT-p type TFT (2) and low VT-n type TFT (3)) of central authorities, the method for mixing P (Fig. 5 (b)) are exposed in formation.At this moment, in low VT-n type TFT (3), reduced n type impurity concentration in fact, in high VT-p type TFT (2), increased p type impurity concentration in fact, so can all make the TFT of 2 kinds of VT to n type, p type.In addition, also can adopt after P is mixed on full surface (to two kinds of n, p) (Fig. 6 (a)) as shown in Figure 6, form the resist figure 10a of the TFT (low VT-p type TFT and high VT-n type TFT) that exposes two ends, the method for mixing B (Fig. 6 (b)).At this moment, in high VT-n type TFT (4), increased n type impurity concentration in fact, in low VT-p type TFT (1), reduced p type impurity concentration in fact, so can all make the TFT of 2 kinds of VT equally to n type, p type.
Like this, by means of being used to control the structure of B of the VT of n channel-type TFT to p channel-type TFT, the structure of P that n channel-type TFT is used to control the VT of p channel-type TFT, perhaps the undope structure of B or P of a part of n channel-type TFT or p channel-type TFT is made up, can make TFT same channel-type with multiple different VT.So, do not need OFF state simulated behavior class circuit by constitute the low VT of the switch, logic class circuit and the needs that need the off-state current characteristic with TFT with different VT, can improve both sides' circuit characteristic.
The following describes the concrete example of the analog circuit that comprises the TFT that forms with said method.Can improve operating rate though constitute analog circuit, enlarge dynamic range with low VT-TFT,, if only constitute analog circuit with the TFT of low VT, the problem that consumes electric power because of leakage current when being created in analog circuit and quitting work.So, by means of the leakage current of the TFT that is provided for when circuit quits work cutting off low VT, with the switch of the TFT formation of high VT, when quitting work, circuit disconnects the TFT switch of high VT, the power consumption that leakage current caused when the inhibition analog circuit quit work is sought the solution of the problems referred to above.
Particularly, the circuit of implementing best mode of the present invention as shown in Figure 7, by input terminal 11, lead-out terminal 12, hot side power supply terminal 13 and low potential side power supply terminal 14 and comprise the analog circuit 20 of low VT-TFT and constitute with the switch 21,21 that high VT-TFT constitutes, analog circuit 20 is according to the input voltage vin that inputs to input terminal 11, from lead-out terminal 12 output output voltage V out. Switch 21,21 is separately positioned between hot side power supply terminal 13 and the analog circuit 20 and between low potential side power supply terminal 14 and the analog circuit 20, by control signal S1 and reverse signal S1B control thereof, control signal S1 is that high level, S1B make during for low level analog circuit 20 activate (can work), and control signal S1 to be low level, S1B make analog circuit 20 non-activation (quitting work) during for high level.
In said structure, the switch 21,21 that utilization is made of high VT-TFT, when containing low VT-TFT on the current path path between input terminal 11, lead-out terminal 12, hot side power supply terminal 13, low potential side power supply terminal 14 each terminal, can cut off this current path, circuit is quit work, and suppress the power consumption that the leakage current when quitting work causes.In addition, potential change that is caused by leakage current in the time of can also suppressing circuit and quit work etc. is to the influence of input terminal 11, lead-out terminal 12.
For example, even between input terminal 11 and low potential side power supply terminal 14, there is the current path path that contains low VT-TFT, also can cut off current path by means of switch 22, even between hot side power supply terminal 13 and lead-out terminal 12, have the current path path that contains low VT-TFT, also can cut off current path by means of switch 21.In addition, even between hot side power supply terminal 13 and low potential side power supply terminal 14, have the current path path, also can cut off current path by means of a certain side of switch 21 or switch 22.
Like this, use method of the present invention, contain the analog circuit 20 of low VT-TFT and the switch 21,21 that constitutes with high VT-TFT, can realize that the high performance of analog circuit (improves operating rate by formation, enlarge dynamic range), can also prevent the power consumption that causes by leakage current simultaneously.By means of this structure that prevents leakage current, even with the occasion of structure applications of the present invention in the drive circuit of the mobile device that requires low-power consumption, the restriction of the leakage current in the time of also can reducing the low VT-TFT that in analog circuit, uses and turn-off.Leakage current when particularly, high VT-TFT being turn-offed requires the electric current (about 10 under threshold voltage usually
-7A) following (about 10/10000ths
-11A), relative therewith, the leakage current when low VT-TFT turn-offs is as long as the electric current (about 10 under threshold voltage
-7A) following just can, thereby can increase the degree of freedom in the design.In addition, the current value that provides above is general standard.
The structure of this analog circuit 20 can be applied to the analog circuit portion of various circuit such as amplifying circuit, power circuit, comparator, drive circuit.In addition, low VT-TFT is enhancement mode preferably, even but a depletion type arranged also it doesn't matter.
Embodiment
Concrete structure to the circuit of above-mentioned execution mode describes below.In addition, simple about following circuit structure for illustrating, though made the structure that possesses low these the two kinds of TFT of TFT of the high TFT of VT and VT, also can make the other structure that also possesses its VT and the 3rd kind of different TFT of these 2 kinds of TFT.In general, the off-state leakage current of the TFT of low VT big than the TFT of high VT.
[embodiment 1]
The analog circuit of the TFT that possesses 2 kinds of VT of the present invention the 1st embodiment at first, is described with reference to Fig. 8.Fig. 8 illustrates the circuit diagram of structure applications of the present invention in the example of differential amplifier circuit.In the following description, the TFT both to high VT and low VT is set at insulated gate transistor.
As shown in Figure 8, the circuit of present embodiment is the simplest differential amplifier circuit that is made of differential stage and amplifying stage, be to hang down VT-TFT to be applied to differential stage (Fig. 8 23), form differentially with low VT-TFT, be formed for cutting off the differential amplifier circuit of differential switch 501 to 101,102 current path with high VT-TFT 101,102.To 101,102, all use the high VT-TFT identical to form except that differential with switch 501.Though both all are the analog circuit portion of flowing through no-load current separately for differential stage, amplifying stage, in the present embodiment, describe just forming differential embodiment to 101,102 with low VT-TFT.Explain Fig. 8 below, differential stage use by the n channel transistor form differential to 101,102; Drive differential to, through transistor switch 501 be connected differential to and low potential side power supply terminal 14 between current source 105; And for differential right load circuit, be connected differential to and hot side power supply terminal 13 between, the current mirroring circuit 103,104 be made up of the p channel transistor constitutes.
The input of current mirroring circuit (leakage of transistor 104 and the tie point of grid) is connected with the leakage of differential right transistor 102, and its output is connected with the leakage of differential right transistor 101, and the leakage of transistor 101 constitutes the output of differential stage.Amplifying stage by the output of differential stage input to that its grid, its source are connected with hot side power supply terminal 13, it leaks the p channel transistor 106 that is connected with lead-out terminal 12; Be connected in series in current source 107 and transistor switch 502 between lead-out terminal 12 and the low potential side power supply terminal 14; And the grid and the transistor switch between the hot side power supply terminal 13 503 that are connected p channel transistor 106 constitute.Control signal S1 inputs to transistor switch 501,502,503 respectively.In addition, in the present embodiment, because 2 differential input terminal are gate terminals of insulated gate transistor, so be between differential input terminal and power supply terminal, lead-out terminal, to have constituted the structure that does not produce current path.
When this differential amplifier circuit work, making control signal S1 is high level, and switch 501,502 is connected, and switch 503 is disconnected.In view of the above, the output of differential stage changes with the voltage difference of 2 differential input voltage Vin (+), Vin (-), the leakage current of p channel transistor 106 is changed control by the gate voltage of p channel transistor 106, output voltage V out by with the balance decision of the electric current of current source 107.As an example, when differential right counter-rotating input terminal (grid of transistor 102) when being connected with lead-out terminal 12, can be formed the voltage follower circuit of exporting the voltage that equates with the input voltage of non-counter-rotating input terminal (grid of transistor 101).In addition, when when work, at differential stage, by the no-load current of current source 105 controls flow through differential to 101,102 and current mirroring circuit 103,104.On the other hand, at amplifying stage, the no-load current that flows through p channel transistor 106 is different with the circuit that is connected lead-out terminal 12, when existing from certain discharging current that lead-out terminal 12 outside circuit flow, the no-load current that flows through p channel transistor 106 is the summed current of discharging current and the electric current controlled by current source 107.In addition, when when lead-out terminal 12 connects capacity load, under the steady-working state after discharging and recharging of electric capacity finished, just the no-load current of being controlled by current source 107 flows through p channel transistor 106.
On the other hand, when quitting work, making control signal S1 is low level, and switch 501,502 is disconnected, and switch 503 is connected.Because the switch 501 of differential stage is in off-state, be cut off so flow into the electric current of low potential side power supply terminal 14, the output of differential stage changes to high potential power voltage VDD.Because the switch 503 of amplifying stage is in on-state, so the gate voltage of p channel transistor 106 is brought up to high potential power voltage VDD, p channel transistor 106 is in off state.In addition, because switch 502 is in off-state, so the current path between lead-out terminal 12 and the low potential side power supply terminal 14 also is cut off.Like this, the work of differential amplifier circuit, the controlled signal S1 that quits work control.
The dynamic range of this differential amplifier circuit (output voltage range of supply voltage scope relatively), its upper limit is high potential power voltage VDD, lower limit is the scope that only deducts the threshold voltage of n channel transistor 101,102 from low potential power source voltage VSS.Therefore, in the structure of Fig. 8 since form with low VT-TFT differential to 101,102, so the working range broadening of differential stage 23 can enlarge the dynamic range of differential amplifier circuit.In addition, this differential amplifier circuit is when quitting work, because differential switch 501 cut-outs that 101,102 current path is formed with high VT-TFT that constitute with low VT-TFT, so do not increase power consumption because of leakage current.
[embodiment 2]
The analog circuit of the TFT that possesses 2 kinds of VT of the present invention the 2nd embodiment is described below with reference to Fig. 9.Fig. 9 is applied to differential stage (Fig. 9 23) with low VT-TFT, form with low VT-TFT differential to 101,102 and current mirroring circuit 103,104, with high VT-TFT formation cut-out differential to the differential amplifier circuit of the switch 501 of the current path of current mirroring circuit.Except that differential to 101,102 and current mirroring circuit 103,104, all use the high VT-TFT identical to form with switch 501.
Differential owing to forming to 101,102 with low VT-TFT, thus can be the same with Fig. 8, widen the working range of differential stage 23, enlarge the dynamic range of differential amplifier circuit.In addition, owing to by means of forming current mirroring circuit 103,104, reduced as load circuit to differential right load, so the work of current mirroring circuit response quickening can be accelerated the work of differential amplifier circuit with low VT-TFT.In addition, also can make low VT-TFT only is applied to current mirroring circuit 103,104, form with high VT-TFT and cut off differential switch 501 differential amplifier circuits current path.At this moment, also the amplifying circuit with Fig. 8 is the same, utilizes low VT-TFT can improve the performance of differential amplifier circuit, by the switch 501 that forms with high VT-TFT is set, can prevent that the power consumption that is caused by the leakage current that hangs down VT-TFT from increasing.
[embodiment 3]
The analog circuit of the TFT that possesses 2 kinds of VT of the present invention the 3rd embodiment is described below with reference to Figure 10.Figure 10 illustrates the circuit diagram of structure applications of the present invention in the other example of differential amplifier circuit.
As shown in figure 10, the circuit of present embodiment is the differential amplifier circuit that low VT-TFT is applied to differential stage (Figure 10 23) and amplifying stage (Figure 10 24), be to form differential to 101 with low VT-TFT, 102 and current mirroring circuit 103,104, with high VT-TFT form cut off differential to the switch 501 of the current path of current mirroring circuit, form the p channel transistor 106 of amplifying stage in addition with low VT-TFT, form the differential amplifier circuit of the switch 504 that is breaking at the current path that is provided with p channel transistor 106 between hot side power supply terminal 13 and the lead-out terminal 12 with high VT-TFT.
The effect of present embodiment is applied to regard to the situation of differential stage (Figure 10 23) with regard to hanging down VT-TFT, identical with Fig. 9, and the working range of having widened differential stage 23 can enlarge the dynamic range of differential amplifier circuit.In addition, in the present embodiment, by form the p channel transistor 106 of amplifying stage (Figure 10 24) with low VT-TFT, the conducting region of the p channel transistor 106 of supply voltage scope is widened, the upper limit of the transistor current driving force of the excursion of differential stage output (gate voltage of transistor 106) improves, thereby can improve the operating rate of differential amplifier circuit.Like this, in the present embodiment, can not cause that also power consumption increases and the performance of raising differential amplifier circuit.
[embodiment 4]
The analog circuit of the TFT that possesses 2 kinds of VT of the present invention the 4th embodiment is described below with reference to Figure 11.Figure 11 illustrates the circuit diagram of structure applications of the present invention in the example of differential amplifier circuit.
Present embodiment is with the differential amplifier circuit of Figure 10 and the differential amplifier circuit that constitutes making up with 2 differential amplifier circuits of the differential amplifier circuit of Figure 10 symmetrical structure (Figure 11 30 and 40) aspect the transistorized polarity.2 differential amplifier circuits 30,40 of Figure 11 become respectively non-counter-rotating input terminal Vin (+) are connected with input terminal 11, and the lead-out terminal of inciting somebody to action separately is connected with lead-out terminal 12 jointly, in addition, 2 differential amplifier circuits all are with counter-rotating input terminal Vin (-) and the lead-out terminal 12 common voltage follower structures that are connected.By means of control signal S1, S2 and their reverse signal S1B, S2B, can control the work of 2 differential amplifier circuits independently and quit work.
In the differential amplifier circuit of Figure 11, when working when differential amplifying circuit 30 controlled signal S1, S1B activation, can carry out high speed charging work by p channel transistor 106, when working, can carry out high rate discharge work by n channel transistor 206 when differential amplifying circuit 40 controlled signal S2, S2B activation.By control signal S1, S1B, S2, S2B (S1B, S2B are respectively the reverse signals of S1, S2) are controlled, can suitably switch high speed charging work and high rate discharge work and carry out work.Therefore, the differential amplifier circuit of Figure 11 can suppress to flow through the electric current of current source 107 and 207, has tried to achieve low-power consumption, again can high speed operation.
In addition, lead-out terminal 12 is through being connected with power supply VCC with the complementary type switch 131,132 of PCB control with signal PC.Thus, can be as required the voltage of lead-out terminal 12 be precharged to supply voltage VCC or carries out pre-arcing.Though constitute the working range of 2 differential amplifier circuits 30,40 of Figure 11 only reduced (to narrow down) constitute separately the amount of differential right transistorized threshold voltage, but, by means of precharge or the pre-arcing of power supply VCC, the drive circuit of Figure 11 can be realized the working range that equates with the supply voltage scope.In addition, power supply VCC also can be the variable power supply with a plurality of voltage levels.
[embodiment 5]
The device used for image display circuit that forms on insulated substrate of the TFT that possesses 2 kinds of VT of the present invention the 5th embodiment is described below with reference to Figure 12 to Figure 15.Figure 12 is the figure that the example that applies the present invention to liquid crystal indicator is shown, and Figure 13 is the figure that the example that is applied to organic EL display is shown.In addition, Figure 14 and Figure 15 are the figure that its particular circuit configurations is shown.
Figure 12 shows and formed the embodiment for the circuit block diagram of the TFT substrate-side that drives the necessary drive circuit of display part, peripheral circuit such as display part and display controller, driver etc. on same insulated substrate.In Figure 12, system power supply and data image signal, control signal are imported from the outside of TFT substrate 31.These signals are sent in the display controller 36, and data image signal is sent in the memory 37.In addition, the transfer approach of data image signal can be the method that transmits accordingly with address signal, perhaps with various methods such as the mode of serial or parallel transmit, according to transfer approach necessary signal, necessary circuit is set.Each square frame part is carried out work control according to the control signal that sends from display controller 36.Power circuit 35 is that the basis produces the necessary supply voltage of each square frame part with the system power supply.Data image signal is stored in the memory 37, and the picture signal of reading from memory 37 according to sequential is transferred in the data driver 34.Data driver 34 amplifies the grayscale voltage of selecting according to data image signal by formations such as gray scale (grade) voltage generating circuit, data latching circuit, decoder, output amplifiers by output amplifier, and exports it to data wire 43.Gate driver 33 outputs are used for selecting successively the sweep signal of each grid line 42.In display part 32, grid line 42 disposes across with data wire 43.In addition, memory 37 preferably can be stored 1 frame or multiple image data.
Figure 12 illustrates display part 32 and be the structure of active array type.In the active array type display part, pixel is configured to rectangular, and each pixel is provided with TFT 41, and the control end of TFT 41 is connected with grid line 42, and drain electrode is connected with data wire 43, and source electrode is connected with pixel electrode.Though done omission in Figure 12, it is also to have and TFT substrate 31 counter substrate in opposite directions, that be provided with transparency electrode, the structure of having enclosed liquid crystal between TFT substrate 31 and counter substrate.Liquid crystal between the electrode (common line 44) of pixel and counter substrate forms liquid crystal capacitance 45, controls the transmissivity of liquid crystal by means of the voltage difference that keeps being applied in the electric capacity two ends with holding capacitor 46 by it, can carry out gray scale and show.In addition, common driver 38 produces the voltage signal that is applied to the electrode on the counter substrate, is sent to electrode (bridging line 44) on the counter substrate from the TFT substrate-side.
Owing on TFT substrate 31 shown in Figure 12, be integrally formed display part 32 and drive circuit and peripheral circuit, so can enough one procedure form TFT and wiring, in the present invention, to going up the TFT that forms, can form the TFT (high VT-TFT and low VT-TFT) that every kind of polarity is had different VT simultaneously at insulated substrate (TFT substrate 31).So, by means of hanging down the analog circuit portion that needs no-load current when VT-TFT is applied to circuit working, and high VT-TFT is applied to logical circuit and switch, can not increase power consumption ground and realize that the operating rate of analog circuit portion improves, dynamic range enlarges, thus, can improve the performance of display unit.
Figure 13 is the same with Figure 12, is the circuit block diagram that has been integrally formed the display unit of display part and drive circuit and peripheral circuit on insulated substrate, shows the circuit block diagram of the TFT substrate-side of representational organic EL display.In Figure 13, to Figure 12 in the element person that has the said function, used the components identical label.Figure 13 also shows the structure that display part 32 is active array types.In the active array type display part of organic EL display, pixel is configured to rectangular, the light-emitting diode OLED 55 (Organic Light Emitting Diode) that each pixel is provided with switching TFT 51, Current Control TFT 54 and forms with organic film, the control end of TFT 51 is connected with grid line 52, its leakage is connected with data wire 53, and its source is connected with the control end of TFT 54.The source of TFT 54 is connected with high potential power VDD, and its leakage is connected with the end of OLED, and low potential power source VSS is applied to the other end of OLED.In addition, low potential power source VSS is applied on the electrode that the cathode base side forms, and this is not shown in Figure 13.When TFT 51 for conducting state, when the voltage corresponding with picture signal is applied to TFT 54, in OLED 55, flow through and the grid voltage of TFT 54 and the corresponding electric current of voltage difference of high potential power VDD, OLED 55 is with luminous with the big or small brightness accordingly of electric current.Like this, cross the electric current of OLED 55, can carry out gray scale and show by control flows.In addition, the common driver 38 among Figure 13 is the circuit that produce the voltage VSS on the electrode that is applied to the cathode base side, when voltage VSS is GND, also it can be set.
Owing on TFT substrate 31 shown in Figure 13, be integrally formed display part 32 and drive circuit and peripheral circuit, so can enough one procedure form TFT and wiring, in the present invention, to going up the TFT that forms, can form the TFT (high VT-TFT and low VT-TFT) that every kind of polarity is had different VT simultaneously at insulated substrate (TFT substrate 31).So, need when the circuit working to be applied to the analog circuit portion of no-load current by means of hanging down VT-TFT, and high VT-TFT is applied to logical circuit and switch, identical with Figure 12, can not increase power consumption ground and realize that the operating rate of analog circuit portion improves, dynamic range enlarges, thus, can improve the performance of display unit.
Figure 12 and Figure 13 are described in detail, concrete example as the analog circuit of Figure 12 and Figure 13, the output amplifier of data driver 34, the adjuster of power circuit 35, the sense amplifier of memory 37 etc. are arranged, by means of a part of element that forms them with low VT-TFT, can enlarge dynamic range, improve the high speed operation performance, thereby can improve the performance of display unit.For example, if improved the operating rate of the output amplifier of data driver 34 according to the present invention, can be at short notice to each data wire 43 output gray level voltage, therefore can realize requiring carrying out at short notice the panel of the high-fineness that data wire drives.
Concrete example as logical circuit and switch, the switch (TFT 41 among the figure) of the pixel portions of gate driver 33, display controller 36, display part 32 etc. is arranged, in order to prevent that the power consumption that leakage current causes from increasing or misoperation, is formed for constituting the TFT of these circuit with high VT-TFT.In addition, in data driver 34, memory 37 etc., also contain many logical circuits, switch.That is, whichsoever circuit block even logical circuit is its main body, also tends to contain a part of analog circuit.The typical example of sort circuit piece has been shown in Figure 14 and Figure 15.
Figure 14 is the figure that the structure example of data driver 34 is shown.The data driver of Figure 14 is by gray scale voltage generating circuit 200, latch circuit 400, decoder 300, amplifying circuit 100 and lead-out terminal group 500 constitute, gray scale voltage generating circuit 200 is made of the resistance string that has applied supply voltage VH and VL at its two ends, output is by the grayscale voltage (many-valued level voltage) of each minute tap generation of resistance string, latch circuit 400 is taken into the image digitization data that are input in the data driver 34, the moment in regulation exports it in the decoder 300, decoder 300 is selected and the corresponding grayscale voltage of exporting from latch circuit 400 of numerical data, export amplifying circuit 100 to, amplifying circuit 100 amplifies the grayscale voltage of input, and it is exported to and data wire (43 of Figure 12, Figure 13 53) lead-out terminal that connects.In addition, the image digitization data that are sent to latch circuit from the outside of data driver are preferably read from the memory 37 of Figure 12 or Figure 13, be directly inputted into latch circuit 400 with parallel form, but, when if data send with the form of serial, also can be made into shift register is set, be taken into successively to the structure of latch circuit 400 with clock synchronization ground.Latch circuit 400 among Figure 14 is logical circuits.In addition, though decoder 300 is circuit of handling many-valued level, also be the circuit that constitutes by switch, it and latch circuit 400 boths form with high VT-TFT.On the other hand, amplifying circuit 100 is analog circuits, can be suitable for the differential amplifier circuit shown in Fig. 8 to Figure 11.By means of applying the present invention to amplifying circuit 100, can not increase power consumption ground and realize that the operating rate of amplifying circuit 100 improves, dynamic range enlarges.In addition, because the gray scale voltage generating circuit 200 of Figure 14 does not contain TFT, so omit its explanation.
In addition, Figure 15 illustrates above-mentioned non-patent literature 1 (modern science publishing house, super LSI goes into gate series 5, " MOS integrated circuit basis ", the figure of the structure example of the memory 37 that forms static RAM (SRAM) on insulated substrate p.64), it is made of memory cell array 600, data input buffer 700, data output buffer 800 and sense amplifier 900 etc.The memory of Figure 15 is write or reads designated memory locations 600 according to the level of writing enabling signal (low level, high level) by row address and column address designated memory cell 600.Sense amplifier 900 will amplify from the data that memory cell 600 is read, and play the work of reading fast.In Figure 15, memory cell 600 is bistable multivibrator structures, and data input buffer 700 and data output buffer 800 all are logical circuits, forms with high VT-TFT respectively.On the other hand, sense amplifier 900 has the roughly the same structure of differential stage (21 among each figure) with Fig. 8 to Figure 10, as the differential stage of Fig. 8 to Figure 10, form differential to, current mirroring circuit with low VT-TFT, the switch current path by being provided for cutting off them, that form with high VT-TFT can be realized not increasing the operating rate that power consumption ground improves sense amplifier 900, enlarges its dynamic range.
In addition, analog circuit can constitute any circuit on the insulated substrate, can use the present invention to it.For example,, various functional circuits also can be set, when in this functional circuit, using analog circuit, also can use the present invention, to improve its performance for pixel portions though the pixel portions among Figure 12, Figure 13 has only been used switching TFT.
In addition, when the circuit blocks such as memory of the data driver that on insulated substrate, is individually formed Figure 14, Figure 15, when it is made chip respectively, self-evident, also can be by applying the present invention to analog circuit, realize not increasing chip power-consumption and high performance is arranged than the chip of prior art.
As shown in the various embodiments described above, come forming circuit by configuration with low VT-TFT and the high VT-TFT that method of the present invention forms, can utilize low VT-TFT to improve the performance of analog circuit, and prevent the leakage of electric current with high VT-TFT.For clear and definite this effect of the present invention, describe hanging down the problem that VT-TFT is applied to the structure (situation that is not comprised among the present invention) of logical circuits such as phase inverter, switch below.
Figure 16 (a) is the figure that the circuit structure of the phase inverter that forms with low VT-TFT is shown.The phase inverter of Figure 16 (a) is made of p channel transistor 901 and n channel transistor 902, the source electrode of described p channel transistor 901 is connected with hot side power vd D, the drain electrode of the drain electrode of described n channel transistor 902 and p channel transistor 901 together with lead-out terminal 12 be connected, the grid of grid and p channel transistor 901 is connected with lead-out terminal 11.Work about phase inverter, when input Vin is low level (VSS), 901 conductings of p channel transistor, n channel transistor 902 turn-offs, output Vout is high level (VDD), and when input Vin was high level (VDD), p channel transistor 901 turn-offed, 902 conductings of n channel transistor, output Vout is low level (VSS).
Like this, a side of p channel transistor 901, n channel transistor 902 turn-offs.But, owing to form p channel transistor 901, n channel transistor 902 with low VT-TFT, so when its off-state leakage current is bigger,, produced the problem that increases power consumption because of the transistorized leakage current that turn-offs though the work of phase inverter can high speed.Relative therewith, in the present invention, will hang down VT-TFT and be used for analog circuit, so its work can high speed, but do not increase power consumption.
Figure 16 (b) illustrates the figure that low VT-TFT is applied to the structure (situation that is not comprised among the present invention) of clock phase inverter.In Figure 16 (b), transistor switch 903 is connected the usefulness of Figure 16 (a) and hangs down between the phase inverter and hot side power supply terminal 13 of VT-TFT formation, transistor switch 904 is connected between the phase inverter and low potential side power supply terminal 14 of Figure 16 (a), and control signal S3 and S4 input to transistor 903,904 grid separately.
In the structure of Figure 16 (b),,, do not influence work so promptly use the leakage current of the transistor 901,902 that hangs down VT-TFT formation big because when the transistor 903,904 of high VT-TFT turn-offed simultaneously, current path was cut off fully yet.But, when at least one side's conducting of the transistor 903,904 of high VT-TFT, often influence work.For example, when transistor 901,902,903,904 was respectively shutoff, conducting, conducting, shutoff, if the leakage current of transistor 901 is big, then electric charge flowed into lead-out terminal 12 from hot side power supply terminal 13, and misoperation often takes place.
Figure 16 (c) illustrates the figure that low VT-TFT is applied to the structure (situation that is not comprised among the present invention) of switch.Figure 16 (c) is and the similar structure of the differential stage of Fig. 8, is the transistor 501 that replaces high VT, is provided with the differential stage of low VT-TFT switch 951.This structure is the structure that the switch that constitutes with high VT-TFT is not set on the differential right current path path that comprises low VT-TFT.Therefore, in that to make S1 be low level, when allowing differential stage quit work, also flow through differential stage by the electric current of current source 915 controls, therefore, if the leakage current of low VT-TFT switch 951 is big, the power consumption when then differential stage quits work therefore increases.Like this, if the switch in the analog circuit is also used low VT-TFT, then produce the problem that power consumption increases.Relative therewith, in the present invention, low VT-TFT is used for the circuit part of the internal current that flows through regulation of analog circuit, but is not used in switch.In addition, about the current path path, owing to be the structure that on the current path path that comprises low VT-TFT, also contains the switch of useful high VT-TFT formation.So do not increase power consumption.
[embodiment 6]
The analog circuit of the TFT that possesses 2 kinds of VT of the present invention the 6th embodiment is described below with reference to Figure 17 in addition.Figure 17 is the figure that the circuit structure of the additional embodiments that applies the present invention to differential amplifier circuit is shown.
As shown in figure 17, the differential stage 23 of the differential amplifier circuit of present embodiment has low VT-TFT, and amplifying stage 24 has low VT-TFT.Promptly, in differential stage 23, constitute with high VT-TFT and to form differential right transistor to 101,102 with insert switching transistor 501 between current source 501 and the power supply VSS, form formation as transistorized 103,104 of the current mirroring circuit of differential right active pull-up circuit with low VT-TFT.Form the p channel transistor 106 of amplifying stage 24 with low VT-TFT, constitute the source electrode of insertion p channel transistor 106 and the transistor 504 between the hot side power supply terminal 13 with high VT-TFT, be formed on the n channel transistor 502 that is connected in series with current source 107 between input terminal 12 and the low potential side power supply terminal 14 with high VT-TFT.In addition, in the occasion that forms current source 105,107 with transistor, owing to current source 105,107 is connected in series with transistor 501,502 respectively, so can use any formation of low VT-TFT and high VT-TFT.Control signal S1 has been input to the grid of the transistor 501,502 of switch element effect, and the reverse signal S1B of control signal S1 is input to the grid of transistor 504.Differential amplifier circuit when work (during activation) transistor 501,502,504 be a conducting state, and when activation (non-) transistor 501,502,504 is an off state when quitting work.
In circuit shown in Figure 17, at signal S1 is high level, when differential stage 23 and amplifying stage (output amplifier stage) 24 is state of activation, for example, the signal voltage Vin (-) of input terminal 11a changes to bigger direction if not the signal voltage Vin (+) of counter-rotating input terminal 11b reverses relatively, then the gate source voltage of n channel transistor 101 increases, leakage current increases, because the voltage drop on the ON resistance of transistor 103, the voltage of the output node of differential stage 23 descends, potential difference between the grid-source of p channel transistor 106 becomes bigger, therefore, the leakage current of p channel transistor 106 (source electric current) increases, because the electric current (sink current) of it and constant current supply 107 is poor, the voltage Vout of lead-out terminal is with rise with signal voltage Vin (+) same phase of non-counter-rotating input terminal 11b (for example in the occasion that is capacity load etc., the stored charge of the load capacitor that is connected with lead-out terminal 12 increases).The signal voltage Vin (-) of input terminal 11a changes to less direction if not the signal voltage Vin (+) of counter-rotating input terminal 11b reverses relatively, then the gate source voltage of n channel transistor 101 reduces, leakage current reduces, because the voltage drop on the ON resistance of transistor 103, the voltage of the output node of differential stage 23 rises, potential difference between the grid-source of p channel transistor 106 becomes littler, therefore, the leakage current of p channel transistor 106 (source electric current) reduces, because the electric current (sink current) of it and constant current supply 107 is poor, the voltage Vout of lead-out terminal descends with signal voltage Vin (+) same phase with non-counter-rotating input terminal 11b, when p channel transistor 106 ends, the electric charge of lead-out terminal 12 is discharged, and voltage Vout reaches the lower limit of low potential power source voltage VSS side.
The low VT-TFT of differential stage 101,102 usefulness among present embodiment Figure 10 constitutes, and uses high VT-TFT.At this moment, though the working range of differential stage 23 do not enlarge, still owing to form the transistor 106 of current mirroring circuit 103,104 and output amplifier stage 24 with low VT-TFT, so the same with Figure 10, can improve the operating rate of differential amplifier circuit.In addition, though current mirroring circuit 103,104 is primary structures, in form all or part of structure of multi-stage type current mirroring circuit with low VT-TFT, also can realize same effect naturally.
In addition, in Fig. 8 to Figure 10 and Figure 17, show and use low VT-TFT to realize high performance embodiment in differential amplifier circuit, the Effect on Performance that the position (element) of using low VT-TFT is reached differential amplifier circuit further elaborates below.
As described in the various embodiments described above, with low VT-TFT form differential amplifier circuit differential to the time (all the other are with high VT-TFT formation) can enlarge the input and output voltage scope.Can improve operating rate when in addition, using the transistor that hangs down VT-TFT formation current mirroring circuit, output amplifier stage.
But, with low VT-TFT form differential to the time, the situation that also exists the operating rate of differential amplifier circuit to reduce.Below situation be exactly this situation: than abundant hour of the threshold voltage of high VT-TFT, at this moment, near the input voltage the hot side supply voltage VDD, the operating rate of differential amplifier circuit descended at the threshold voltage that constitutes differential right low VT-TFT.
Be explained with reference to Fig. 8, when 101,102 input voltage vin (+) was near hot side supply voltage VDD, differential common source current potential to 101,102 also rose to the VDD side when differential.At this moment, the amplitude maximum of differential right output voltage (drain voltage of transistor 101) is supply voltage VDD and differential to the voltage range between 101,102 the common source current potential.Therefore, to 101,102 threshold voltage very hour the amplitude of differential right output voltage diminishes when low VT-TFT differential, and the amplification of amplifier transistor 106 reduces, and consequently the operating rate of differential amplifier circuit reduces.But, when the upper limit of the output voltage range of differential amplifier circuit is low more than hot side supply voltage VDD, do not have problems.Therefore, in order to enlarge the input and output voltage scope, when to differential to low VT-TFT the time, need to consider the upper limit and the operating rate of input and output voltage scope, set the threshold voltage of low VT-TFT.That is, though differential amplifier circuit shown in Figure 8 can enlarge the input and output voltage scope, the possibility that also exists speed to reduce.
Differential amplifier circuit shown in Figure 10 can enlarge the input and output voltage scope, compares with differential amplifier circuit shown in Figure 8, also can improve operating rate.
In addition, the differential amplifier circuit of Figure 17 is though input and output voltage scope no change can improve operating rate fully.
By the above position (element) of selecting to use low VT-TFT, can improve needed performance.
[embodiment 7]
Below the structure applications that will hang down VT-TFT and high VT-TFT is described in the embodiment of differential amplifier circuit amplifying circuit in addition.Figure 18 is the figure of circuit structure that the source follower amplifying circuit of the present invention the 7th embodiment is shown.With reference to Figure 18, the source follower amplifying circuit of present embodiment possesses: n channel transistor 111 that is connected in series between hot side power supply terminal 13 and lead-out terminal 12 and p channel switch transistor 511; And current source 112 that between low potential side power supply terminal 14 and lead-out terminal 12, is connected in series and n channel switch transistor 512.Grid to n channel transistor 111 applies input voltage vin, and the grid of transistor 512,511 is applied control signal S1 and its reverse signal S1B respectively.As control signal S1, when S1B is respectively high and low level, this source follower amplifying circuit is activated; When control signal S1, S1B were respectively low, high level, this source follower amplifying circuit was by non-activation.The effect of the amplifying circuit of Figure 18 is: n channel transistor 111 carries out source follower work when Vin rises, boosted output voltages Vout, and be stabilized in and depart from input voltage vin and only be the voltage of the amount of voltage between the grid-source of transistor 111.In addition, when Vin descends, n channel transistor 111 was once becoming OFF state, output voltage V out descends because of the discharge process of current source 112, when the potential difference of voltage Vin and Vout surpasses the threshold voltage of transistor 111, transistor 111 becomes ON state once again, and is stabilized in and departs from input voltage vin only on the voltage for the amount of voltage between the grid-source of transistor 111.In the amplifying circuit of Figure 18, form transistor 111 with low VT-TFT, form other transistors with high VT-TFT.The effect that obtains thus is: because the threshold voltage of transistor 111 reduces, so the dynamic range of amplifying circuit enlarges, the operating rate of source follower improves simultaneously.On the other hand, owing to form transistor switch 511,512 with high VT-TFT, the power consumption that does not also take place to be caused by leakage current when amplifying circuit quits work increases.
[embodiment 8]
Below with reference to Figure 19 the present invention the 8th embodiment is described.In each embodiment of the Fig. 8 that uses low VT-TFT and even Figure 11, Figure 17 and amplifying circuit shown in Figure 180, be provided with the special switch transistor that is used to cut off current path independently from hot side power supply terminal 13 to low potential side power supply terminal 14.In contrast, present embodiment is to make high VT-TFT have the embodiment of switching function simultaneously.
Figure 19 makes the transistor 105 of the current source 105 that constitutes differential stage 23 shown in Figure 8 have the circuit diagram of function of the switch 501 of Fig. 8, has removed the switching transistor 501 of Fig. 8.
As typical example, Figure 19 shows differential stage 23, not shown amplifying stage 24.The high VT-TFT of current source 105 usefulness forms, and bias voltage VB1 is applied to its grid.Then, when activating differential amplifier circuit, bias voltage VB1 is set at the voltage of regulation, when non-activation differential amplifier circuit, bias voltage VB1 is set at supply voltage VSS.When the non-activation of differential amplifier circuit, owing to close with the current source 105 of high VT-TFT formation, so can not increase power consumption because of leakage current.Like this, in the present embodiment,, can realize effect, the effect identical with differential stage shown in Figure 8 23 by the current source 105 that constitutes with transistor is provided with switching function.
Figure 20 is the figure that the change example of structure shown in Figure 19 is shown.With reference to Figure 20 as can be known, this figure makes formation also possess the circuit diagram of switching function as the transistor 103,104 of the current mirroring circuit of the differential right active load of differential stage shown in Figure 8 23.In example shown in Figure 20, from the differential stage 23 of Fig. 8, removed switch transistor 501, added the p channel transistor 108,109 of high VT-TFT.P channel transistor 108 is connected between the leakage of the common gate of the transistor 103,104 that constitutes current mirroring circuit and transistor 104, control signal S1B (reverse signal of control signal S1) imports its grid, transistor 109 is connected between the common gate and hot side power supply terminal 13 of the transistor 103,104 that constitutes current mirroring circuit, and control signal S1 imports its grid.When activating differential amplifier circuit, make control signal S1, S1B be respectively high and low level.At this moment, transistor 108,109 is turn-on and turn-off respectively, and transistor 103,104 constitutes current mirroring circuit.On the other hand, when making the non-activation of differential amplifier circuit, make control signal S1, S1B be respectively low, high level.At this moment, transistor 108,109 turn-offs respectively and conducting, and the common gate of transistor 103,104 is hot side supply voltage VDD, and transistor 103,104 becomes OFF state, between the leakage and grid of transistor 104, also the transistor 108 because of closed condition becomes nonconducting state.
Because the transistor 103,104,108 that forms with high VT-TFT all turn-offs, so no-load current is cut off fully, does not increase power consumption because of leakage current.Like this, in the present embodiment,, can realize effect, the effect identical with the differential stage 23 of embodiment shown in Figure 8 by current mirroring circuit extra switch function to constituting by transistor 103,104.
Though more than be to be illustrated with reference to Fig. 8, but other embodiment of the present invention also can be the same with present embodiment, be the structure arbitrarily that forms as follows: promptly, cut off switch no-load current, that form with high VT-TFT and not necessarily cut off the special switch of electric current, it has switching function and other functions simultaneously concurrently.
In addition, as the change example of Fig. 8 etc., also can constitute the p channel transistor 106 of amplifying stage with source follower structure (n channel transistor).At this moment, become the structure that source electrode is connected with low potential side power supply terminal 14, drain electrode is connected with the grid of source follower transistor, the complementary signal S1B of control signal S1 imports grid of switch 503.In addition, the amplifying stage 24 of Figure 10 etc. can certainly be made source follower structure shown in Figure 180.In addition, when the transistor of amplifying stage is made follower configuration, inversion input signal Vin (-) and non-inversion input signal Vin (+) become the state that state shown in Figure 10 is exchanged, input terminal 11a becomes the non-counter-rotating input terminal of acknowledge(ment) signal voltage Vin (+), and input terminal 11b becomes the counter-rotating input terminal of acknowledge(ment) signal voltage Vin (-).
In the above-described embodiments, for 5V series, the threshold value of high VT-TFT for example is ± 1.0～± 1.2V about, the threshold value of low VT-TFT for example is ± 0.0～± 0.2V about.Here ,+be the threshold value of n channel-type TFT ,-be the threshold value (voltage between the grid-source during p channel-type TFT conducting) of p channel-type TFT.Threshold value height about p channel-type TFT compares with the absolute value that removes symbol, and the threshold value of the threshold ratio 1.2V (absolute value of 1.2V) of 0.2V (absolute value of 0.2V) is low in other words.
More than, with reference to accompanying drawing embodiments of the invention are illustrated, but the present invention is only limited to the foregoing description, in the scope that each of claim scope that is also contained in the application naturally requires, and various distortion, correction that those skilled in the art can carry out.
For example, in the above-described embodiments, be that example is illustrated with polycrystalline SiTFT (polycrystallinesilicon TFT), still, the present invention of course not is defined in polysilicon membrane with transistorized channel region.For example, the present invention also contains the expansion because of silicon crystallization particle diameter, and transistorized channel region is positioned at an intragranular situation.
In addition, the formation that utilizes laser to carry out the polysilicon film of crystallization also can be carried out crystallization with solid state growth.
Also have, effect of the present invention, effect are not only to use the manufacture method of the thin film semiconductor device that limits to realize.In the above-described embodiments, with the manufacture method that realizes with few process number the present invention has been described, but also can have carried out channel doping several times, same channel-type has been formed the TFT of different VT.At this moment,, for example comparing the occasion of more paying attention to circuit performance, by making as (structure of explanation can improve circuit performance among Fig. 7～Figure 11, Figure 17～Figure 20) at embodiments of the invention with cost though increased process number (manufacturing cost raising).In the occasion that the manufacture method with other constitutes, also be the same.
But, utilize the manufacture method of explanation in the above-described embodiments, can suppress the increase of manufacturing cost, can realize the raising of circuit performance again.
Claims (14)
1. thin film semiconductor device, being provided with at least on the insulating properties substrate with the crystal silicon film is the 1st conductivity type thin-film transistor and the 2nd conductivity type thin-film transistor of active layer, it is characterized in that,
Comprise: the 1st thin-film transistor that in channel region, contains above-mentioned the 1st conductivity type of the 1st dopant;
The 2nd thin-film transistor that in channel region, does not contain above-mentioned the 1st conductivity type of above-mentioned the 1st dopant; With
The 3rd thin-film transistor that in channel region, contains above-mentioned the 2nd conductivity type of above-mentioned the 1st dopant with the basic concentration that equates,
Above-mentioned the 1st dopant is a kind of among B and the P,
In the above-mentioned the 1st and the 2nd thin-film transistor of above-mentioned the 1st conductivity type, one has the high threshold voltage of absolute value, and another has the low threshold voltage of absolute value.
2. thin film semiconductor device as claimed in claim 1 is characterized in that:
The the above-mentioned the 1st and the 2nd thin-film transistor of above-mentioned the 1st conductivity type contains the 2nd dopant respectively in channel region,
Above-mentioned the 2nd dopant is the another kind beyond above-mentioned the 1st dopant among B and the P.
3. thin film semiconductor device as claimed in claim 1 is characterized in that,
Also be included in the 4th thin-film transistor of above-mentioned the 2nd conductivity type that does not contain above-mentioned the 1st dopant in the channel region,
In the above-mentioned the 3rd and the 4th thin-film transistor of above-mentioned the 2nd conductivity type, one has the high threshold voltage of absolute value, and another has the low threshold voltage of absolute value.
4. thin film semiconductor device as claimed in claim 1 is characterized in that:
At least have and when circuit working, need the analog circuit of no-load current portion and switch, above-mentioned analog circuit portion constitutes by means of the low thin-film transistor of absolute value that contains the above-mentioned threshold voltage in the above-mentioned the 1st or the 2nd thin-film transistor on the current path of above-mentioned no-load current, and above-mentioned switch is made of the high thin-film transistor of above-mentioned threshold voltage in the above-mentioned the 1st or the 2nd thin-film transistor.
5. thin film semiconductor device as claimed in claim 3 is characterized in that,
At least have and when circuit working, need the analog circuit of no-load current portion and switch, above-mentioned analog circuit portion constitutes by means of the low thin-film transistor of absolute value that contains the above-mentioned threshold voltage in above-mentioned the 1st～the 4th thin-film transistor on the current path of above-mentioned no-load current, and above-mentioned switch is made of the high thin-film transistor of above-mentioned threshold voltage in above-mentioned the 1st～the 4th thin-film transistor.
6. as claim 4 or 5 described thin film semiconductor devices, it is characterized in that:
Above-mentioned switch is contained in above-mentioned analog circuit portion on the current path of above-mentioned no-load current, utilize this switch to cut off above-mentioned no-load current.
7. thin film semiconductor device as claimed in claim 6 is characterized in that:
Above-mentioned analog circuit portion utilizes the conducting and the cut-out of the above-mentioned no-load current that is caused by above-mentioned switch, controls the work of this circuit and quits work.
8. as claim 4 or 5 described thin film semiconductor devices, it is characterized in that:
When the low thin-film transistor of the absolute value that contains above-mentioned threshold voltage on the current path path of the above-mentioned no-load current between each terminal at input terminal, lead-out terminal and the power supply terminal of above-mentioned analog circuit portion, on this current path path, contain above-mentioned switch.
9. as claim 4 or 5 described thin film semiconductor devices, it is characterized in that:
The thin-film transistor that the thin-film transistor that the absolute value of above-mentioned threshold voltage is high and the absolute value of above-mentioned threshold voltage are low all is an enhancement mode.
10. as claim 4 or 5 described thin film semiconductor devices, it is characterized in that:
Above-mentioned analog circuit portion comprises any in amplifying circuit, power circuit or the comparator.
11., it is characterized in that as claim 4 or 5 described thin film semiconductor devices:
Above-mentioned analog circuit portion contains the low thin-film transistor of the absolute value of above-mentioned threshold voltage and contain the differential amplifier circuit of above-mentioned switch on this differential right current path path differential centering at least.
12. thin film semiconductor device as claimed in claim 1 is characterized in that:
Comprise other thin-film transistors that have with above-mentioned the 1st conductivity type of any all different threshold voltage of the above-mentioned the 1st and the 2nd thin-film transistor of above-mentioned the 1st conductivity type.
13. thin film semiconductor device as claimed in claim 1 is characterized in that:
Between power supply terminal or in the current path between power supply terminal and the input/output terminal, have the high thin-film transistor of the absolute value of above-mentioned threshold voltage in the above-mentioned the 1st or the 2nd thin-film transistor and comprise the circuit of the low thin-film transistor of the absolute value of above-mentioned threshold voltage in the above-mentioned the 1st or the 2nd thin-film transistor
The thin-film transistor that the absolute value of above-mentioned threshold voltage is high is controlled to be conducting by the control signal that its control terminal is applied or ends, foregoing circuit is activated during the high thin-film transistor conducting of the absolute value of above-mentioned threshold voltage, the high thin-film transistor of the absolute value of above-mentioned threshold voltage by the time foregoing circuit be non-activation.
14. thin film semiconductor device as claimed in claim 3 is characterized in that,
Between power supply terminal or in the current path between power supply terminal and the input/output terminal, have the high thin-film transistor of the absolute value of above-mentioned threshold voltage in above-mentioned the 1st～the 4th thin-film transistor and comprise the circuit of the low thin-film transistor of the absolute value of above-mentioned threshold voltage in above-mentioned the 1st～the 4th thin-film transistor
The thin-film transistor that the absolute value of above-mentioned threshold voltage is high is controlled to be conducting by the control signal that its control terminal is applied or ends, foregoing circuit is activated during the high thin-film transistor conducting of the absolute value of above-mentioned threshold voltage, the high thin-film transistor of the absolute value of above-mentioned threshold voltage by the time foregoing circuit be non-activation.
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| EP0782250B1 (en) * | 1995-12-29 | 2001-05-30 | STMicroelectronics S.r.l. | Offset compensating method and circuit for MOS differential stages |
| JPH10200114A (en) * | 1996-12-30 | 1998-07-31 | Semiconductor Energy Lab Co Ltd | Thin film circuit |
| JP3737240B2 (en) * | 1997-04-24 | 2006-01-18 | 富士通株式会社 | Semiconductor integrated circuit device |
| JP3947308B2 (en) * | 1998-06-17 | 2007-07-18 | 沖電気工業株式会社 | Semiconductor integrated circuit |
-
2003
- 2003-09-10 CN CN200610071008A patent/CN100590877C/en not_active Expired - Lifetime
- 2003-09-10 CN CN2008101308743A patent/CN101359899B/en not_active Expired - Lifetime
-
2010
- 2010-10-25 JP JP2010238088A patent/JP5351868B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CN1848441A (en) | 2006-10-18 |
| CN101359899B (en) | 2011-02-09 |
| JP2011103648A (en) | 2011-05-26 |
| CN101359899A (en) | 2009-02-04 |
| JP5351868B2 (en) | 2013-11-27 |
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