JP2005276601A - Field emission type electron emitting element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly densely integrated field emission type electron emitting element wherein withstand voltage between a negative electrode and a gate electrode is sufficiently secured, and efficiency of electron emission is high, and also to provide a method for manufacturing the field emission type electron emitting element. <P>SOLUTION: This field emission type electron emitting element has: the negative electrode formed on a substrate; an insulating film formed on the substrate while having a hole the opening of which is positioned on the negative electrode; a gate electrode formed on the insulating film so that the opening of the hole is surrounded; and a plurality of carbon nanotubes grown in the hole so as to stand close together from the negative electrode. A plurality of the carbon nanotubes stand close together away from the inside wall of the hole by a desired distance or longer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a field electron emission device using carbon nanotubes as an electron emission source and a method for manufacturing the same.

Carbon nanotubes used as an electron emission source of a field electron emission device are grown by chemical vapor deposition (hereinafter abbreviated as CVD) so as to stand inside a hole having a diameter of about 10 μm. This carbon nanotube has a very thin shape with a length of several μm and a diameter of about 10 nm. When placed in a space with an electric field, electric field concentration occurs at the tip of the carbon nanotube, and electron emission occurs even at a low voltage. Is possible.
This field-type electron-emitting device is composed of a layered cathode electrode, insulating film, and gate electrode provided on a substrate. For example, a circular hole (cavity) is formed in the gate electrode and the insulating film. The carbon nanotubes are grown so that they stand inside the pores. Then, by applying a voltage between the gate electrode and the cathode electrode, an electric field concentration is generated at the tip of the carbon nanotube connected to the cathode electrode, and electrons are emitted from the tip.

  Carbon nanotubes can be grown while being adjusted to a desired length by the CVD method. However, since the diameter is as thin as about 10 nm, the carbon nanotubes do not always grow straight. For example, when grown in a hole, the position of the tip of the carbon nanotube expands outward to some extent. Then, from the time when the length of the carbon nanotube exceeds the thickness of the insulating film, the carbon nanotube comes into contact with the gate electrode.

  In order to solve this problem, the insulating film is made thick so that the tip of the carbon nanotube is inside the opening of the hole. Further, the diameter of the inner periphery of the gate electrode is increased so that the inner periphery of the gate electrode is separated from the edge of the opening of the hole. In addition, the length of the carbon nanotube is shortened. For example, carbon nanotubes are etched using hydrogen gas plasma and shaped significantly shorter (see, for example, Non-Patent Document 1).

S. Kang, 12 others, Low Temperature Carbon Nanotubes for Triode-Type Field-Emitter Array, Society for Information Display 03 Digest, 2003. 802-805

However, if a silicon oxide film that is generally used as an insulating film is thickened, the stress of the film increases, so that there is a problem that cracks occur and the film peels off. Therefore, it is difficult to increase the thickness of the insulating film.
In addition, in order to make the diameter of the inner periphery of the gate electrode larger than the diameter of the hole, it is necessary to prepare a photomask separately and add a new molding process by a photolithography method, which increases the manufacturing cost. . Further, a machining margin between the edge of the opening of the hole and the inner periphery of the gate electrode is required, and there is a problem that it becomes a hindrance when many fine holes are accumulated.
In addition, since there is a correlation between the electron emission characteristics and the length of the carbon nanotube, if the length of the carbon nanotube is shortened, the electric field concentration at the tip of the carbon nanotube is weakened, and the efficiency of electron emission is reduced. is there. Moreover, since the whole carbon nanotube receives the damage by plasma, there exists a problem that the stability as a structure also worsens.

  An object of the present invention is to provide a field-type electron-emitting device that has a sufficiently high withstand voltage between a cathode electrode and a gate electrode, has a high electron emission efficiency, and is integrated at a high density. Another object of the present invention is to provide a method for manufacturing the field-type electron-emitting device.

  The field-type electron-emitting device according to the present invention has a cathode electrode formed on the substrate and a hole located on the cathode electrode, and the insulating film formed on the substrate and the opening of the hole are surrounded. In the field-type electron-emitting device having a plurality of carbon nanotubes grown in the hole so as to stand from the gate electrode and the cathode electrode formed on the insulating film, the plurality of carbon nanotubes are desired from the inner wall of the hole. The forest stands more than a distance away.

  The effect of the field-type electron-emitting device according to the present invention is that the carbon nanotubes are erected from the cathode electrode at a distance of a desired distance or more from the inner wall of the hole, so that the gate electrode surrounding the opening of the hole The carbon nanotubes are separated from each other, and a short circuit due to contact between the two can be prevented.

Embodiment 1 FIG.
In the field electron emission device provided with a plurality of field electron emission devices according to the first embodiment, a plurality of field electron emission devices 2 are arranged on a substrate 1 in a grid pattern. The cathode electrode 3 is connected to each column by a cathode wiring (not shown), and the gate electrode 4 of the field-type electron-emitting device 2 is connected to each row by a gate wiring (not shown). In this way, the cathode wiring and the gate wiring are arranged orthogonally, and by applying a voltage between the cathode wiring and the gate wiring, a potential difference is generated between the carbon nanotube 5 and the gate electrode 4, and the carbon nanotube 5 The electric field concentrates at the tip.
Next, the field-type electron-emitting device 2 constituting the field-type electron-emitting device will be described with reference to FIG. FIG. 1 is a sectional view of a field electron-emitting device 2 using a carbon nanotube according to Embodiment 1 of the present invention as an electron emission source. Since all the field electron-emitting devices 2 are the same, only one will be described.
This field-type electron-emitting device 2 is formed on a substrate 1, a substrate 1, a cathode electrode 3 on which carbon nanotubes 5 are grown, and a hole 6 with the cathode electrode 3 at the bottom passing therethrough. The insulating film 7 is covered, and the gate electrode 4 is formed on the insulating film 7 so as to surround the opening 8 of the hole 6.
Further, a plurality of carbon nanotubes 5 are erected in the remaining portion 10 located in the center excluding the peripheral edge portion 9 on the cathode electrode 3 through the catalyst layer 11 (see FIG. 2). The average length of the carbon nanotubes 5 is about 2 μm. The carbon nanotubes 5 are tilted inwardly at the tilted portion 12 of the remaining portion 10 so that the tips of the carbon nanotubes 5 gather at the center. The degree of collapse is 70 to 80 degrees. The tilted portion 12 has a ring shape, and the width is equal to or greater than the average length of the carbon nanotubes 5. On the other hand, the carbon nanotubes 5 stand vertically on the standing part 13 of the remaining part 10.

The substrate 1 is a white glass substrate having a 20-inch square shape and a thickness of 2 mm. Besides, high strain point glass, quartz, silicon, alumina, ceramics, and the like can be used as the substrate 1.
The cathode electrode 3 is made of an aluminum film formed by sputtering, and in addition, most metals and alloys thereof can be used. For example, chromium, titanium, molybdenum, tungsten, titanium silicide, titanium nitride, gold, silver, an aluminum-based alloy, and the like can be given. The thickness of the aluminum film can be a suitable thickness between 10 nm and 1 μm, more preferably between 20 and 400 nm. Further, as a method of forming this film, other methods such as a CVD method, a plating method, or a printing method may be used.

The insulating film 7 is a silicon oxide film formed by a plasma CVD method. In addition, a silicon nitride film, a heat resistant insulating resin, or the like can be used. The thickness of the silicon oxide film can be set to an appropriate thickness of 50 nm to 10 μm, and is preferably set to a range of 300 nm to 2 μm from the viewpoint of heat resistance, structural stability, insulation resistance, and the like.
The hole 6 has a cylindrical or prismatic shape, and its cross section is a circle or polygon with a diameter of 1 to 50 μm.

  The gate electrode 4 is made of an aluminum film formed by sputtering, and in addition to this, most metals and their alloys can also be used. For example, chromium, titanium, molybdenum, tungsten, titanium silicide, titanium nitride, gold, silver, an aluminum-based alloy, and the like can be raised. The thickness of this film can be a suitable thickness between 10 nm and 1 μm, more preferably between 100 and 500 nm. It can also be formed by using a method such as a vapor deposition method, a CVD method, a plating method, or a printing method.

The catalyst layer 11 is an Fe—Ni alloy formed by a vapor deposition method, and may be an alloy containing at least Fe, Ni, Co, or the like. The thickness of the catalyst layer 11 is several nm.
The carbon nanotube 5 is grown by the CVD method. Further, the carbon nanotubes 5 are peeled off from the peripheral edge 9 of the cathode electrode 3 by a local peeling process which will be described in detail later, and are not present there. Further, the carbon nanotubes 5 grown on the tilted portion 12 of the remaining portion 10 by the tilting process which will be described in detail later are tilted inward so that the tips gather at the center.
The carbon nanotubes 5 formed as the electron emission source are adjusted so that the average length is 2 μm. Note that the average length of the carbon nanotubes 5 may be 0.3 μm to 5 μm. When it is less than 0.3 μm, the electron emission characteristics are insufficient. On the other hand, if it exceeds 5 μm, it takes too much time for growth, which is inappropriate. Further, when the carbon nanotubes 5 are grown by the CVD method, the carbon nanotubes 5 are grown upright in the vertical direction as a whole.

Next, a method for manufacturing the field-type electron-emitting device 2 will be described with reference to FIGS. 2 to 4 are cross-sectional views of the field electron-emitting device at each stage during manufacture. FIG. 5 is a cross-sectional view of an ultrasonic irradiation apparatus used for the local peeling process and the tilting process.
First, a 20-inch square, 2 mm thick white glass substrate as the substrate 1 is cleaned and inserted into a sputtering apparatus.
Next, an aluminum film is coated on the substrate 1 using an aluminum target. Next, a resist is coated on the entire surface of the substrate 1. Next, the resist is removed leaving a predetermined pattern. Next, the aluminum film is patterned by etching with an acid or the like to form cathode electrodes 3 each connected by a cathode wiring having a width of several hundreds of μm.
Next, an insulating film 7 made of a silicon oxide film is formed on the cathode electrode 3 in the plasma CVD apparatus. A resist is coated on the entire surface of the insulating film 7. Next, etching is performed so that the resist remains in the insulating film 7 except for the portion where the hole 6 is formed, and then the insulating film 7 is etched with an acid or the like. In this way, the insulating film 7 is peeled off from the upper surface of the cathode electrode 3 to form the hole 6.
Next, an aluminum film is coated on the substrate 1 on which the insulating film 7 is formed by a sputtering method. Then, the etching resist is left so that the aluminum film is exposed in the portion surrounding the hole 6 and the gate wiring portion, and the exposed aluminum film is etched. In this way, the gate electrode 4 is formed. At the same time, a gate wiring having a width of several hundred μm is patterned, and the gate electrode 4 is connected to each row by the gate wiring.

  Next, a catalyst layer 11 for growing carbon nanotubes is formed on the cathode electrode 3 exposed at the bottom of the hole 6. The catalyst layer 11 covers the resist except only the growth region 14 where the carbon nanotubes 5 are grown, and then deposits the Fe—Ni alloy having a thickness of several nanometers on the entire surface by vapor deposition, and then lifts off the resist. By the treatment, the catalyst layer 11 is left only at the bottom of the hole 6. A field-type electron-emitting device at this stage is shown in FIG. 2, and the element at this stage is referred to as an element 15 before CNT growth.

Next, carbon nanotubes 5 are grown on the pre-CNT growth element 15 formed in this way by the CVD method. As a raw material for CVD, a hydrocarbon gas such as acetylene, ethylene, or methane, or an organic compound such as ethanol, methanol, or tetrahydrofuran (C ₄ H ₈ O: THF) can be used. As conditions for the growth of the carbon nanotubes 5 by the CVD method, a substrate temperature of 350 ° C. to 700 ° C. and a pressure of 10 to 100,000 Pa can be used. Furthermore, the conditions of the substrate temperature of 400 ° C. to 600 ° C. and the pressure of 100 Pa to 10000 Pa are more preferable as the CVD conditions of the carbon nanotube 5. The field-type electron-emitting device at this stage is shown in FIG. 3, and the element at this stage is referred to as a CNT grown element 16.

Next, the local peeling process of the carbon nanotube 5 will be described below by taking a typical ultrasonic irradiation process as an example. FIG. 5 shows a cross-sectional view of the ultrasonic irradiation apparatus used for this local peeling treatment.
First, the structure of the ultrasonic irradiation apparatus will be described with reference to FIG. The ultrasonic irradiation apparatus includes a water tank 21 that can store a liquid 27, a stirring blade 22 that stirs the liquid in the water tank 21, a liquid supply port 23 that injects the liquid 27 into the water tank 21, and a liquid that discharges the liquid 27 from the water tank 21. It has a discharge port 24, an ultrasonic transducer 25 fixed so as to face the water tank 21, and a power source 26 for driving the ultrasonic transducer 25.

  The CNT-grown element 16 on which the carbon nanotubes 5 are grown is inserted into the water tank 21 of such an ultrasonic irradiation apparatus. At this time, the vibration surface of the ultrasonic transducer 25 is arranged so that the wavefront of the ultrasonic wave propagating in the liquid 27 is perpendicular to the forest nanotube direction of the carbon nanotube 5. Next, a liquid 27 made of a mixture of ethyl alcohol and water is injected, and the entire CNT-grown element 16 is immersed in the liquid 27. In addition, as the liquid 27, a liquid and a solution that can be volatilized chemically and stably, such as isopropyl alcohol and acetone, can also be used.

When the CNT grown element 16 is set in this way and the ultrasonic transducer 25 is vibrated, the ultrasonic wave propagating in the liquid 27 is excited along with the vibration. The output level of the ultrasonic wave is effective to remove foreign matter on the CNT grown element 16 and is strong enough not to damage the electrode portion of the electron emission element.
In order to see the effect of ultrasonic irradiation, the shape of the carbon nanotube 5 was evaluated by changing the irradiation time. First, partial peeling of the carbon nanotube 5 occurred from the stage of the irradiation time of 30 seconds. Further, it was found that only the peripheral edge 9 of the growth region 14 of the carbon nanotube 5 was selectively peeled until the irradiation time was 2 minutes.

  When ultrasonic waves are applied to the CNT grown element 16, the ultrasonic waves penetrate into the holes 6, cavitation occurs on the surface of the cathode electrode 3, and a force acts in a direction in which the carbon nanotubes 5 are peeled off by cavitation. When the ultrasonic wave enters the hole 6, the ultrasonic wave enters the remaining portion 10 of the growth region 14 of the cathode electrode 3 where the carbon nanotubes 5 are erected at the same peak value. Under the influence of the interference of the inner wall 18 of the hole 6, the ultrasonic wave has a high peak value and enters the part 9. Therefore, the carbon nanotube 5 is peeled from the peripheral edge 9. By irradiating the ultrasonic wave for an appropriate period, the carbon nanotube 5 can be left only in the remaining portion 10 away from the inner wall 18 of the hole 6 by a desired distance.

Note that the width for selectively removing the carbon nanotubes 5 can be adjusted to some extent by the intensity of ultrasonic waves and the processing time. FIG. 4 shows a field-type electron-emitting device at this stage, and the element at this stage is referred to as a local peeling element 17.
By this local peeling treatment, the carbon nanotubes 5 at the peripheral edge 9 of the growth region 14 are selectively peeled off, so that the carbon nanotubes 5 that come into contact with the gate electrode 4 are removed, and the gate electrode 4 and the cathode electrode 3 are removed. Can solve the problem of short circuit between. The irradiation with ultrasonic waves does not shorten the carbon nanotubes 5 themselves, and the electron emission characteristics do not deteriorate. In addition, since the structure of the carbon nanotube 5 is not affected, the electron emission characteristics are also maintained.

Next, the carbon nanotube tilting process will be described. This tilting process also uses an ultrasonic irradiation device in the same manner as the local peeling process.
As described above, after leaving the carbon nanotubes 5 only in the remaining portion 10 of the growth region 14, the local peeling element 17 is pulled up and dried with a drying device or the like, and the attached liquid is volatilized to complete the processing. By pulling up from the liquid in this manner, the tip of the carbon nanotube 5 is tilted as tightly as the carbon nanotube 5 located at the center of the remaining portion 10, that is, at the outer edge of the remaining portion 10. This process is referred to as a tilt process. This tilted portion has a ring shape, and the width of the ring is set to be equal to or greater than the average length of the carbon nanotubes 5. In addition, since the carbon nanotubes 5 in the remaining portion 10 are held together, the mechanical strength can be increased. The tilting mechanism is considered to be the formation of droplets accompanying the drying of the liquid and the capillary phenomenon and surface tension effect that occur at that time.

Next, the aggregate form of the carbon nanotubes 5 will be described. FIG. 6 shows an aggregated form of carbon nanotubes immediately after being grown by the CVD method. FIG. 7 shows an aggregated form of carbon nanotubes of the field electron-emitting device. The carbon nanotubes 5 immediately after being grown by the CVD method are vertically grown and grown as shown in FIG. Subsequent local peeling treatment and tilting treatment yield an electric field type electron-emitting device as shown in FIG. The aggregate form of the carbon nanotubes 5 of this field-type electron-emitting device is that the carbon nanotubes 5A are vertically arranged at the center of the aggregate, and the carbon nanotubes 5B that are fallen inward at the periphery and are radially aligned in the horizontal direction. And is formed from.
The tilting principle of the carbon nanotube 5B can be considered to be affected by the capillary phenomenon, the surface tension effect, etc. that occur when the liquid 27 adheres to the carbon nanotube 5 and when the liquid volatilizes during drying. .

  Since the carbon nanotubes 5 shaped by these processes are shaped so as to move away from the gate electrode 4 by an amount corresponding to the length of the carbon nanotubes 5 (about 2 μm), problems such as short circuits are eliminated. I understood. Furthermore, since the carbon nanotube 5 </ b> A forested on the standing portion 13 of the remaining portion 10 of the growth region 14 is supported by the tilted carbon nanotube 5 </ b> B of the tilted portion 12, structural stability is ensured. it is conceivable that.

  Note that the carbon nanotubes 5A of the standing portions 13 of the remaining portion 10 can also be thinned out in a honeycomb shape by increasing the intensity of ultrasonic waves. This has the effect of increasing the proportion of the carbon nanotubes 5 having isolated tips, and therefore advantageously works to cause electric field concentration, and thus also has the effect of improving the electron emission characteristics.

In addition, since the ultrasonic irradiation apparatus can use a generally used ultrasonic cleaning apparatus or the like, the carbon nanotube shaping method that is a feature of the present invention is useful as a process that is inexpensive and requires only a short time. It is a thing.
In addition, an integrated structure of carbon nanotubes aligned in the vertical direction or the vertical direction and carbon nanotubes aligned in the horizontal direction can be formed.

  In addition, it can be said that it is important to be able to shape the carbon nanotubes grown in the vertical direction in a desired direction. The method of horizontally arranging carbon nanotubes in the desired direction has no effective method at present, and it is useful as a technique that can be applied to the production of electronic devices such as transistors that are advantageous in the lateral direction. Can be considered.

  In the ultrasonic irradiation apparatus, as shown in FIG. 5, a liquid supply port 23 is attached to the water tank 21, and extra liquid is discharged from the liquid discharge port 24 while replenishing the liquid 27. The liquid 27 is stirred by the stirring blade 22. As a result, the carbon nanotubes 5 that have been peeled off and floated in the liquid 27 can be efficiently and reliably eliminated, and reattachment and the like can be prevented.

  Alternatively, an electrode may be installed in the liquid 27 and an electric field may be applied, and a method of efficiently and reliably removing the carbon nanotubes 5 that are separated and float in the liquid 27 may be used in combination.

  When the ultrasonic irradiation time is short or when the intensity of the ultrasonic wave is weak, the carbon nanotube 5 is hardly peeled off, but it is possible to selectively tilt the carbon nanotube 5 in the peripheral portion in the drying process. is there.

  By applying such local peeling treatment and tilting treatment to the substrate on which the CNTs are grown, a short circuit between the gate electrode and the cathode electrode caused by the contact between the carbon nanotube and the gate electrode can be excluded. Since the electron emission characteristics of the carbon nanotube are not deteriorated by performing these treatments, a good field emission type electron-emitting device can be provided. Moreover, these processes can be performed by using an inexpensive ultrasonic irradiation apparatus.

  Moreover, since the carbon nanotubes located at the peripheral edge of the collection of carbon nanotubes are tilted inward, the gate electrode and the carbon nanotubes can be further separated. Furthermore, since the carbon nanotube located in the central portion is supported by the carbon nanotube located in the peripheral portion, it is possible to prevent the carbon nanotube located in the central portion from falling down.

Further, since the average length of the carbon nanotubes and the width of the peripheral portion are the same, even if the carbon nanotube in the central portion falls outside, it does not come into contact with the gate electrode. Furthermore, by making the width of the peripheral portion larger than the average of the lengths of the carbon nanotubes, the contact between the carbon nanotubes and the gate electrode can be prevented more reliably.
If the width of the peripheral portion is made larger than necessary, the number of carbon nanotubes that stand is reduced and the amount of emitted electrons is reduced. Therefore, an appropriate upper limit value of the width is determined based on desired characteristics of the electron-emitting device. It is done.

Embodiment 2. FIG.
The field-type electron-emitting device according to the second embodiment of the present invention is different in that different local peeling processing and tilting processing are performed, but the aggregated form of the carbon nanotubes 5 of the field-type electron-emitting device is the same. The description regarding the form is omitted. Further, the processes up to the CNT grown element 16 are the same as those in the manufacturing method of the first embodiment, and thus the description of the same parts is omitted.
First, an example in which the local peeling process and the tilting process are performed by jetting a high-speed water flow will be described. FIG. 8 is a cross-sectional view of a high-speed water jet apparatus used for the local peeling process and the tilting process.
The high-speed water jet device is connected to a water tank 31 for collecting the jetted liquid, a jet nozzle 32 for jetting a jet stream of high-pressure gas mixed with droplets to the CNT grown element 16, and a jet nozzle 32. A high-pressure gas pipe 33 for supplying high-pressure gas to the pipe, a liquid supply pipe 34 for supplying liquid to the jet nozzle 32, a linear movable mechanism 35 for moving the jet nozzle 32 in a straight line, and a collected liquid A liquid discharge port 36 for discharging to the outside is provided.

First, the CNT grown element 16 is disposed in the water tank 31 so that the moving direction of the linear movable mechanism 35 and the substrate 1 are parallel to each other. In addition, the jet direction of the high-speed water jet jetted from the jet nozzle 32 is set substantially parallel to the direction in which the carbon nanotubes 5 are standing.
Next, a high-pressure gas composed of high-pressure nitrogen is supplied from the high-pressure gas pipe 33, and water is supplied from the liquid supply pipe 34. A liquid that is chemically stable and volatilizes, such as ethyl alcohol, isopropyl alcohol, and acetone, can also be used as the liquid. The liquid supplied in this way is mixed with the jet flow of high-pressure gas and jetted from the jet nozzle 32 onto the CNT grown element 16.

  When high-speed water jet is performed over the entire surface of the CNT-grown element 16, a field electron-emitting device 2 similar to that shown in FIG. 1 can be obtained. By this high-speed water jet treatment, the carbon nanotube 5 can be locally peeled and tilted, and the same effect as in the first embodiment can be obtained. By ejecting the high-speed water stream, the ejected liquid droplets collide with the carbon nanotubes 5 vigorously, so that the carbon nanotubes 5 are peeled in order from the peripheral portion 9 of the growth region 14 of the carbon nanotubes 5 that are susceptible to force. It is thought that this is because

  Further, using the boiling water jet processing apparatus shown in FIG. 9 provided with the heating mechanism 37 in the liquid supply pipe 34 of the high speed water jetting apparatus shown in FIG. 8, the boiling water is jetted onto the CNT grown element 16 in the same manner as the high speed water jet. By doing so, a field-type electron-emitting device 2 similar to that shown in FIG. 1 can be obtained.

  Moreover, you may supply the vapor | steam containing mist instead of the liquid and high pressure gas to the high-speed water-jet apparatus of FIG. By using the mist-containing steam injection device shown in FIG. 10 having the mist-containing steam injection mechanism 38 for injecting the mist-containing steam, the mist-containing steam is injected into the CNT grown element 16 in the same manner as the high-speed water jet. Thus, a field-type electron-emitting device 2 similar to the above can be obtained.

Embodiment 3 FIG.
FIG. 11 is a cross-sectional view of a field electron emission device according to Embodiment 3 of the present invention.
The field-type electron-emitting device 40 according to the third embodiment is different from the field-type electron-emitting device 2 according to the first embodiment in the aggregate form of carbon nanotubes. The aggregate form of the first embodiment is formed from carbon nanotubes 5A that stand vertically to the central part, and carbon nanotubes 5B that fall toward the center of the aggregate at the peripheral part surrounding them. The degree of the fall is about 70 to 80 degrees. On the other hand, in the collective form of the third embodiment, the central portion falls vertically toward the center of the collective carbon nanotube 5A that stands vertically in the central portion, and the peripheral portion surrounding it, as in the first embodiment. The carbon nanotube 5C is formed. The inclination of the carbon nanotube 5C is about 45 ° C. on average.

Next, a method for manufacturing the field-type electron-emitting device 40 will be described. The manufacturing process up to the CNT grown element 16 is the same as in the first embodiment. The ultrasonic irradiation apparatus is the same as that in the first embodiment. Description of similar parts is omitted.
The CNT grown element 16 is inserted into the water tank 21 of this ultrasonic irradiation apparatus. Next, a liquid 27 made of ethyl alcohol is poured into the water tank 2, and the entire CNT-grown element 16 is immersed in the liquid 27. Next, the ultrasonic transducer 25 is vibrated, and the CNT-grown element 16 is irradiated with ultrasonic waves for 30 seconds.
Next, the CNT-grown element 16 that has been irradiated is pulled up, and the liquid 27 that has been naturally dried is volatilized to complete the process.
The reason why the carbon nanotubes 5C tilted at an inclination of about 45 degrees is formed is that the rate of peeling of the carbon nanotubes 5 is small when ultrasonic irradiation is performed for a short period of 30 seconds. This is probably because the remaining carbon nanotubes 5 were so large that they did not fall down to the side.

  Thus, the electric field type electron-emitting device 40 shaped by shortening the time of ultrasonic irradiation has a problem of short circuit between the gate electrode 4 and the cathode electrode 3 due to the contact between the gate electrode 3 and the carbon nanotube 5. Is resolved.

  As in the second embodiment, the electric field electron-emitting device 40 of the third embodiment can be obtained by selecting appropriate conditions for the high-speed water jet process, the boiling water jet process, or the mist-containing steam jet process. it can.

Embodiment 4 FIG.
FIG. 12 is a cross-sectional view of a field electron emission device according to Embodiment 4 of the present invention.
The field-type electron-emitting device 50 according to the fourth embodiment is different from the field-type electron-emitting device 2 according to the first embodiment in the aggregate form of carbon nanotubes. The aggregate form of the first embodiment is formed from carbon nanotubes 5A that stand vertically to the central part, and carbon nanotubes 5B that fall toward the center of the aggregate at the peripheral part surrounding them. On the other hand, the aggregate form of the fourth embodiment is formed from carbon nanotubes 5 that stand vertically throughout.

Next, a method for manufacturing the field-type electron-emitting device 50 will be described. The manufacturing process up to the CNT grown element 16 is the same as in the first embodiment. The high-speed water jet device is the same as that in the second embodiment. Description of similar parts is omitted.
First, the CNT grown element 16 is placed in the water tank 31 so that the moving direction of the linear movable mechanism 35 and the substrate 1 are parallel. In addition, the jet direction of the high-speed water jet jetted from the jet nozzle 32 is matched with the direction in which the carbon nanotubes 5 are standing.
Next, a high-pressure gas composed of high-pressure dehydrated nitrogen is supplied from the high-pressure gas pipe 33, and acetone is supplied from the liquid supply pipe 34. The acetone thus supplied is mixed with the jet flow of the high-pressure gas and jetted from the jet nozzle 32 onto the CNT grown element 16. Since the liquid is acetone, it evaporates instantaneously, so that no droplets are accumulated in the carbon nanotubes 5. Immediately after high-pressure gas injection of acetone, only nitrogen is injected.
The reason why the carbon nanotubes 5 are constituted only by the vertically standing carbon nanotubes 5 is considered to be because the drying of the liquid occurs instantaneously and the force for tilting the carbon nanotubes is not applied. Moreover, it is considered that carbon nanotubes remaining on the peripheral portion were removed by spray drying of nitrogen.

  In such a field-type electron-emitting device 50, since the tips of the carbon nanotubes 5 are discrete, electric field concentration becomes remarkable, and a desired amount of electrons can be emitted with a low voltage.

As in the second embodiment, the field-type electron-emitting device 50 according to the fourth embodiment can be obtained by selecting appropriate conditions for the boiling water flow jetting process or the mist-containing steam jetting process.
In addition, the field-type electron-emitting device 50 according to the fourth embodiment can be obtained by irradiating ultrasonic waves in the same manner as in the first embodiment using acetone as the liquid, then pulling up and simultaneously blowing nitrogen and drying. .

1 is a cross-sectional view of a field-type electron-emitting device according to Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view of the pre-CNT growth element in the middle of manufacture according to the first embodiment. FIG. 3 is a cross-sectional view of a CNT-grown element that is being manufactured according to the first embodiment. FIG. 3 is a cross-sectional view of the local peeling element in the middle of manufacturing according to the first embodiment. 4 is a cross-sectional view of an ultrasonic irradiation apparatus used for local peeling processing and tilting processing in the manufacturing process according to Embodiment 1. FIG. It is a perspective view of a CNT grown element. 1 is a perspective view of a field-type electron-emitting device according to Embodiment 1. FIG. FIG. 6 is a cross-sectional view of a high-speed water jet device used for local peeling processing and tilting processing in a manufacturing process according to Embodiment 2. It is sectional drawing of the boiling water flow injection apparatus used for another local peeling process and tilting process in the manufacturing process concerning Embodiment 2. FIG. It is sectional drawing of the mist containing steam injection apparatus used for another local peeling process and tilting process in the manufacturing process concerning Embodiment 2. FIG. It is sectional drawing of the field type electron emission element concerning Embodiment 3 of this invention. It is sectional drawing of the field type electron emission element concerning Embodiment 4 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Substrate, 2, 40, 50 Field type electron-emitting device, 3 Cathode electrode, 4 Gate electrode, 5 Carbon nanotube, 6 hole, 7 Insulating film, 8 (hole) opening, 9 (growth region) peripheral part, 10 (Growth region) remaining portion, 11 catalyst layer, 12 (remaining portion) tilted portion, 13 (remaining portion) standing portion, 14 growth region, 15 CNT pre-growth element, 16 CNT grown element, 17 local release element , 18 (hole) inner wall, 21, 31 water tank, 22 stirring blade, 23 liquid supply port, 24, 36 liquid discharge port, 25 ultrasonic oscillator, 26 power supply, 27 liquid, 32 injection nozzle, 33 high pressure gas piping , 34 Liquid supply piping, 35 Linear movable mechanism, 37 Heating mechanism, 38 Mist-containing steam injection mechanism.

Claims (9)

A cathode electrode formed on the substrate, the opening has a hole located on the cathode electrode, and the insulating film formed on the substrate is formed on the insulating film so as to surround the opening of the hole. In a field electron emission device having a plurality of carbon nanotubes grown in the hole so as to stand from the gate electrode and the cathode electrode,
The field-type electron-emitting device, wherein the plurality of carbon nanotubes stand from the inner wall of the hole by a desired distance or more.   The collective form of the plurality of carbon nanotubes includes a central portion composed of carbon nanotubes standing vertically from the cathode electrode and a ring-shaped peripheral portion composed of carbon nanotubes that are inclined inward. The field-type electron-emitting device according to claim 1, wherein the field-type electron-emitting device is configured. A cathode electrode formed on the substrate, the opening has a hole located on the cathode electrode, and the insulating film formed on the substrate is formed on the insulating film so as to surround the opening of the hole. In a field electron emission device having a plurality of carbon nanotubes grown in the hole so as to stand from the gate electrode and the cathode electrode,
The collective form of the plurality of carbon nanotubes includes a central portion composed of carbon nanotubes standing vertically from the cathode electrode and a ring-shaped peripheral portion composed of carbon nanotubes that are inclined inward. A field-type electron-emitting device comprising: The average length of the plurality of carbon nanotubes is 0.3 μm to 5 μm,
4. The field-type electron-emitting device according to claim 2, wherein a width of the ring-shaped peripheral edge is equal to or greater than an average length of the carbon nanotubes. Forming a cathode electrode patterned in a desired shape on a substrate;
Forming an insulating film provided with a hole whose opening is located on the cathode electrode on the substrate;
Forming a gate electrode patterned in a desired shape surrounding the hole on the insulating film;
A step of growing a plurality of carbon nanotubes so as to stand from the cathode electrode in the hole;
In a manufacturing method of a field-type electron-emitting device having
A method of manufacturing a field-type electron-emitting device, comprising a step of peeling a carbon nanotube grown on a portion close to the inner wall of the hole among the plurality of grown carbon nanotubes.   6. The method of manufacturing a field-type electron-emitting device according to claim 5, further comprising a step of tilting the carbon nanotubes grown on the peripheral edge of the plurality of grown carbon nanotubes toward the center of the hole. Forming a cathode electrode patterned in a desired shape on a substrate;
Forming an insulating film provided with a hole whose opening is located on the cathode electrode on the substrate;
Forming a gate electrode patterned in a desired shape surrounding the hole on the insulating film;
A step of growing a plurality of carbon nanotubes so as to stand from the cathode electrode in the hole;
In a manufacturing method of a field-type electron-emitting device having
A method for manufacturing a field-type electron-emitting device, comprising a step of tilting a carbon nanotube grown on a peripheral portion of the plurality of grown carbon nanotubes toward a center of the hole.   The exfoliating step includes any one of a step of irradiating the substrate on which the carbon nanotubes are grown with ultrasonic waves in a liquid, injecting a high-speed water stream, injecting a boiling water stream, or injecting a mist-containing vapor. The method for manufacturing a field-type electron-emitting device according to claim 5.   The step of defeating the carbon nanotubes includes a step of drying after immersing the substrate on which the carbon nanotubes are grown in a liquid, or a step of drying after spraying the liquid onto the substrate on which the carbon nanotubes are grown. A method for manufacturing a field-type electron-emitting device according to claim 6 or 7.

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