JPH0730084A - Two-dimensional contact image sensor - Google Patents

Abstract

PURPOSE:To provide the title two-dimensional contact image sensor having excellent switching characteristics of a thin film transistor while cutting down power consumption capable of enhancing the sensitivity thereof without deteriorating the resolving power at all. CONSTITUTION:The title two-dimensional contact image sensor share the wiring for the light-shielding layer in the channel region 2 of a thin film transistor 6 on a switching element and the bias wire 11 feeding constant voltage to a photodetecting element 2. Through these procedures, the wiring for the light- shielding layer can be used both for the bias wire 11 thereby enabling the photodetecting area to be widened so that the sensitivity may be enhanced without deteriorating the resolving power at all while wiring resistance may be lowered using aluminum for the bias wire 11, for cutting down the power consumption further lessening the unfavorable effect on a gate pulse by reducing the capacity at the intersection of a gate wire 10 with the bias wire 11 thereby enabling the excellent switching characteristics to be displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-dimensional contact type image sensor used in an image input device such as a facsimile, a scanner, an optical character reading device, etc., and particularly, to improve sensitivity and reduce power consumption, Good switching characteristics 2
A three-dimensional contact type image sensor.

[0002]

2. Description of the Related Art In a conventional image reading apparatus, an IC sensor in which a CCD (charge coupled device) sensor or a MOS sensor is formed in a linear one-dimensional form is used to reduce an image of an original on the IC sensor. For example, a reduction-type image sensor that scans by scanning or a one-dimensional image sensor in which light-receiving elements such as photodiodes are arranged in a length that is approximately the same as the width of the original is used to form and read an equal-magnification erect image on the sensor. There were double sensors and so on.

However, the reduction-type image sensor requires a long optical path length in order to reduce the image width of the document to the chip length of the IC sensor, and has a problem such as aberration in the peripheral portion of the lens. Further, the 1x sensor has a shorter optical path length than the reduction sensor, but the optical fiber lens array provided for forming an 1x erect image is expensive, and there is a problem such as chromatic aberration.

Therefore, as a solution to the above problem, a full contact type one-dimensional image sensor is currently known. FIG. 7 is a schematic cross-sectional explanatory view of the one-dimensional perfect contact image sensor. In the following, the one-dimensional perfect contact image sensor will be simply referred to as the one-dimensional contact image sensor. In the one-dimensional contact image sensor, a plurality of light receiving elements 2 which are photoelectric conversion units are arranged on a transparent substrate 1 in a lengthwise shape having the same length as the document width to form a light receiving element array. A lighting portion 3 is formed between the elements 2 and is entirely covered with a transparent protective film 4.

In the one-dimensional contact type image sensor having the above-mentioned structure, the light incident from the back surface of the substrate 1 through the lighting portion 3 is
It is reflected by the surface of the original 5 set on the transparent protective film 4,
Reflected light according to the brightness of the original enters the light receiving element 2 to generate a photocurrent, and the photocurrent is read for each light receiving element to obtain an image signal.

Then, the reading operation (scanning) of the two-dimensional image by the one-dimensional image sensor electrically scans in the reading direction (main scanning direction) of the one-dimensional sensor and at the same time,
This is performed by moving either the document or the one-dimensional sensor relatively by a mechanical means in a direction orthogonal to the main scanning direction (sub-scanning direction). In general, a type that conveys a document is used in a facsimile or the like, and a type that moves a sensor unit is used in a scanner or the like.

[0007] However, the original is limited to a sheet-like type for conveying the original, and the entire type of the type for moving the sensor unit is large, and the shape of the sensor part is limited. The problem is that it is not suitable for applying a sensor, and both require high-performance mechanical scanning means and an optical system that guides irradiation light to the document surface on the upper surface of the sensor, resulting in high cost. there were.

Further, in the one-dimensional contact type image sensor,
Since the same sensor is repeatedly used for each line, there is a problem that resolution is lowered due to unread signal charges, deterioration of photoresponse characteristics, and the like, and the accumulation time corresponds to the scanning speed of one line. Therefore, when reading at high speed, there is a problem that the signal charge becomes small and the S / N ratio decreases.

Therefore, as a solution to the problem of the one-dimensional contact image sensor, for example, a two-dimensional contact image sensor as shown in FIG. 8 has been proposed. Figure 8
FIG. 4 is an equivalent circuit diagram of a two-dimensional contact image sensor.
As shown in FIG. 8, the two-dimensional contact type image sensor includes a light receiving area 7'consisting of pixels 7 arranged two-dimensionally in the row and column directions, a gate line 10 for selectively scanning each row and each column. Data line 9 for selectively scanning the gate and gate line 10
Are connected to the shift register 14, and the analog multiplexer 13 to which the data line 9 is connected.

Next, the structure of one pixel of the two-dimensional contact image sensor will be described with reference to FIGS. 9 and 10. 9 is a plan explanatory view of one pixel of the two-dimensional contact image sensor, and FIG. 10 is a sectional explanatory view of a BB ′ portion of FIG. As shown in FIGS. 9 and 10, each pixel includes a light receiving element 2 which is a photoelectric conversion portion formed on a substrate 1, a thin film transistor (TFT) 6 which is a switching element,
And a gate line 10 connected to the gate electrode 18 in the row direction around the pixel.
The data line 9 connected to the source electrode in the column direction, the bias line 11 connected to the light receiving element, and the wiring of the light shielding layer 12 covering the semiconductor active layer (channel region 20 ') above the gate electrode 18 of the thin film transistor in the column direction are formed. Has been formed.
Here, the bias line 11 supplies a bias voltage to the metal electrode 15 below the light receiving element 2.

In the two-dimensional contact type image sensor having the above structure, the light incident from the back side of the substrate 1 through the light collecting portion 3 is reflected by the document surface and reaches the light receiving portion of the light receiving element 2, where A photocurrent is generated by the reflected light according to the brightness of the document, and charges corresponding to the generated photocurrent are accumulated in the parasitic capacitance of the light receiving element, etc.
The image signal is read out by transferring the electric charge accumulated by turning it off and outputting it as an electric signal.

Here, the light shielding layer 12 is made of aluminum (A
1), it is formed on the semiconductor active layer 20 so as to cover the semiconductor active layer 20 in order to prevent light from entering the semiconductor active layer 20 of the thin film transistor and causing photoelectric conversion. Incidentally, the light shielding layer 12 is generally connected to a constant potential, for example, a ground (GND) level.

By the way, in the two-dimensional contact image sensor, when the resolution to be realized is set, the pixel pitch in the x (row) direction and the y (column) direction is determined, and the pixel area is limited. All of the above constituent elements must be formed in the pixel, and it is necessary to improve the aperture ratio (ratio of the light receiving area in the pixel area) in order to increase the sensitivity. For that purpose, the non-light-receiving area needs to be minimized, and the lighting part 3 for illumination can be made smaller by making the light source brighter. However, the thin film transistor 6 and each wiring part have device characteristics (for example, It is difficult to reduce the size because it is limited by the on-state resistance of the thin film transistor, each wiring resistance, etc.) and the process rule.

On the other hand, as a conventional two-dimensional contact type image sensor, there is also one having a structure as shown in FIGS. FIG. 11 is a plan view of another conventional two-dimensional contact image sensor, and FIG. 12 is a sectional view taken along line CC ′ of FIG.
It is sectional explanatory drawing of a part. In the two-dimensional contact image sensor shown in FIG. 11, the metal electrode 15 of the light receiving element 2 is not formed individually for each pixel, but is formed as a common electrode common for each column. In this way, when the metal electrode 15 is used as the common electrode, the bias line above the light receiving element is unnecessary, and the manufacturing method is easy. Incidentally, as a technical document related to FIGS. 11 and 12, Japanese Patent Laid-Open No. 4-309
There is a 059 publication.

[0015]

However, in the conventional two-dimensional contact type image sensor using the individual bias electrodes, a thin film transistor, a data line,
The gate line, the bias line, and the daylighting part are non-photoelectric conversion parts, and it is difficult to reduce these non-photoelectric conversion parts. Therefore, the area occupied by the non-photoelectric conversion parts in the pixel is considerably large, and thus the photoelectric conversion There is a problem that the area of the part becomes small and the sensitivity of the image sensor is lowered.
If the area of the photoelectric conversion unit is increased to improve the sensitivity, the area of one pixel becomes large, resulting in a problem that the resolution is lowered.

Further, in the conventional two-dimensional contact type image sensor using the common electrode shown in FIGS. 11 and 12, the common electrode of the light receiving element is formed of chromium (Cr) having a large sheet resistance, so that it is consumed. Since the power is increased and the common electrode of the light receiving element made of chromium (Cr) is formed above the gate line of the thin film transistor through a thin insulating layer so as to be orthogonal to the gate line, the gate is formed in each pixel. There is a problem in that a capacitance is generated at the intersection of the line and the common electrode, and as the distance from the gate pulse transmitting portion increases, the influence of the capacitance increases, the waveform of the gate pulse is broken, and the switching characteristics of the thin film transistor deteriorate.

The present invention has been made in view of the above circumstances, and provides a two-dimensional contact type image sensor which improves sensitivity without lowering resolution, consumes less power, and has good switching characteristics of thin film transistors. With the goal.

[0018]

According to the present invention for solving the problems of the above-mentioned conventional example, a pixel having a light receiving element and a thin film transistor as a switching element connected to the light receiving element is two-dimensionally formed on a substrate. In the two-dimensional contact type image sensor arranged in a matrix, the wiring of the light shielding layer for shielding the channel region of the thin film transistor and the bias line for supplying a constant voltage to the light receiving element are common.

[0019]

According to the present invention, since the wiring of the light shielding layer for shielding the channel region of the thin film transistor and the bias line of the light receiving element are used in common as the two-dimensional contact type image sensor, the bias line is formed above the thin film transistor. The structure makes it possible to increase the area of the photoelectric conversion portion without enlarging the pixel area, improve the sensitivity without lowering the resolution, and also to increase the vertical distance between the bias line and the gate line of the thin film transistor. Since the capacitance can be increased, the capacitance formed at the intersection of the bias line and the gate line is reduced, the influence on the gate pulse can be reduced, and the switching characteristics of the thin film transistor can be improved. If it is made of low aluminum, power consumption can be reduced.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The basic configuration of the two-dimensional contact image sensor according to the embodiment of the present invention is the same as the configuration of the conventional two-dimensional contact image sensor shown in FIG. That is, the image sensor of this embodiment has two elements in the row direction and the column direction.
A light receiving area 7'consisting of pixels 7 arranged in a three-dimensional matrix, a gate line 10 for selectively scanning each row and a data line 9 for selectively scanning each column, and
The gate line 10 is connected to the shift register 14, and the data line 9 is connected to the analog multiplexer 13.

Next, the structure of each pixel will be described. FIG. 1 is an explanatory plan view of one pixel of a two-dimensional contact image sensor according to an embodiment of the present invention, and FIG.
It is a section explanatory view of an A'portion. Each pixel corresponds to FIG. 1 and FIG.
As shown in FIG. 3, the light receiving element 2 is formed on a transparent substrate 1 such as glass, a thin film transistor (TFT) 6 as a switching element, and a light collecting section 3, and the gate electrode of the thin film transistor 6 is row by row. The light receiving element 2 is connected to the gate line 10, the source electrode is connected to the data line 9 for each column, the light receiving element 2 is connected to the drain electrode of the thin film transistor 6, and the light receiving element 2 is a characteristic part of this embodiment.
The metal electrodes 15 are connected to the bias line 11 which also serves as the light shielding layer of the thin film transistor 6 for each column.

Here, the light receiving element 2 and the thin film transistor 6
A specific configuration of the above will be described with reference to FIG. The light receiving element 2 is formed separately for each light receiving element, and a metal electrode 15 as a lower electrode made of chromium (Cr) is formed on the substrate 1,
A photoconductive layer 16 made of hydrogenated amorphous silicon (a-Si: H) and a transparent electrode 17 made of indium tin oxide (ITO), which is similarly divided and formed, are sequentially laminated to form a sandwich type. That is, the metal electrode 1
5, the photoconductive layer 16 and the transparent electrode 17 are formed separately for each pixel.

The thin film transistor (TFT) 6 is formed on the substrate 1.
A gate electrode 18 made of chromium (Cr), a gate insulating layer 19 made of silicon nitride (SiNx), aS
A semiconductor active layer 20 made of i: H and a top insulating layer 2 made of SiNx provided so as to face the gate electrode 18.
1. An ohmic contact layer 22 made of n + hydrogenated amorphous silicon (n + a-Si: H) formed so as to cover a part of the semiconductor active layer 20 and the top insulating layer 21, a source electrode 23 made of Cr, and Drain electrode 2
4, an interlayer insulating layer 25 made of polyimide thereon, and a wiring layer 26 made of aluminum (Al) on the interlayer insulating layer 25, and in particular, a bias line 11 also serving as a light shielding layer on the top insulating layer 21 is sequentially laminated. It is an inverted staggered thin film transistor.

Bias line 11 which is a characteristic part of this embodiment
Are formed in the column direction on top of the top insulating layer 21 of the thin film transistor 6, and in the semiconductor active layer 20, the gate electrode 1
It also functions as a light-shielding layer for preventing light from entering the upper channel region 20 'and causing a photoelectric conversion action. As a result, the wiring of the light-shielding layer and the bias line, which have been separately formed in the past, are made common, and one metal line in the column direction in the pixel can be reduced, and the area of the light receiving portion can be increased. To do.

For example, aluminum (A
1) and a process rule with a minimum line width of 10 μm and a minimum interline space of 10 μm, and the pixel pitch in the column direction is Y μm, the pixel width is about 20 μm × Yμ.
The area of the light receiving element can be expanded by the space of m.

Further, by forming the bias line 11 with Al having a sheet resistance lower than that of Cr, it is possible to reduce the power consumption for applying the bias voltage in the image sensor. Further, since the metal electrode 15 is an individual electrode formed separately for each pixel and a voltage is supplied from the bias line 11 formed on the upper portion,
At the intersection of the bias line 11 and the gate line 8 connected to the gate electrode 8 of the thin film transistor 6, some layers of SiNx, polyimide, etc. are formed between the gate line 8 and the bias line 11. The capacitance at the intersection can be reduced, and the influence on the gate pulse propagating through the gate line 8 can be reduced.

Next, the circuit configuration and driving method of the two-dimensional contact image sensor of this embodiment will be described with reference to FIGS. FIG. 3 is an equivalent circuit diagram of the two-dimensional image sensor, and FIG. 4 is an equivalent circuit diagram of one pixel. Figure 3
And as shown in FIG. 4, in the light receiving area, the pixel 7 has m rows ×
The light receiving elements 2 in each pixel are arranged and formed in a matrix of n columns, and the photodiodes Pi, j (i = 1 to m, j = 1 to
It is equivalently expressed by n) and the parasitic capacitance. Further, each light receiving element 2 is connected to the drain electrode of the thin film transistor Ti, j (i = 1 to m, j = 1 to n), and the source electrode of the thin film transistor Ti, j is connected via the data line 9 to the load capacitance CLj (j. = 1 to n), and the data line 9 is connected to the analog multiplexer 13
It is connected to the. In addition, a bias line 1 is connected to each light receiving element
A common bias voltage VB is applied via 1
In this embodiment, the bias voltage VB is 5V.

A shift register 14 for generating a gate pulse φ is connected to the gate electrode of each thin film transistor Ti, j via a common gate line 10 for each row. Then, all the thin film transistors in the i-th row of the image sensor are turned on at the same time by the gate pulse φi, and the charge accumulated in the parasitic capacitance or the like is transferred to the load capacitance CLj.

As shown in FIG. 4, the photocharge generated in each light receiving element by the photocurrent ip is applied to the parasitic capacitance CPD of the light receiving element, the additional capacitance CADD and the overlap capacitance CGD between the drain and the gate of the thin film transistor for a certain period of time. After being accumulated, the thin film transistor Ti, j is used as a switch for charge transfer, and the charge in a specific row to which the gate pulse φ of the voltage VG is applied is transferred and accumulated in the load capacitance CLj via the data line 9 to be transferred to the analog multiplexer. The voltage value VL of the data line 9 is sequentially read by 13 and the image signal is output.

Here, the influence on the operation of the thin film transistor by applying 5 V to the bias line 11 which also serves as the wiring of the light shielding layer (light shielding wiring) will be described with reference to FIG. FIG. 5 shows the ID of the thin film transistor in this embodiment.
It is a VG characteristic diagram. Channel width is 180-200μ
m, channel length 10 to 15 μm, overlap (overlap between gate electrode and source / drain) 2 to 4 μm
, The gate voltage VG = 5V,
Drain voltage VD (voltage applied to the drain electrode side) = 5
In the case of V, the drain-source current ID (ON current) when the light-shielding wiring that becomes the bias line 11 is grounded and when 5 V is applied to this light-shielding wiring is compared. As shown in FIG. 5, when the light-shielding wiring is grounded, the on-current is 1.0 to 1.5 μA (see FIG.
(A)), when VB = 5V is applied to the light-shielding wiring, the on-current is 1.2 to 1.8 μA (FIG. 5 (b)), so that it is about 20% larger when 5V is applied. .

Similarly, the drain-source current ID (off current) in the case of VG = -5V and VD = 5V is 0.2 to when the light-shielding wiring to be the bias line 11 is grounded.
0.5 picoA (FIG. 5A), 0.4 to 0.6 picoA (FIG. 5B) when 5 V is applied to the light-shielding wiring, which is about 20% larger when 5 V is applied.

From the graph of FIG. 5, the threshold voltage V
When th is obtained, it changes from 1.2 to 1.5 V when the light shielding wiring is grounded and from 1.0 to 1.3 V when the light shielding wiring 5 V is applied.
However, the on / off ratio is 6 digits both when the light-shielding wiring is grounded and when 5 V is applied, which is almost the same and a sufficient on / off ratio is obtained. Therefore, even if the bias line 11 also serving as the light-shielding wiring is formed above the channel, the switching characteristics hardly change and the driving of the image sensor is hardly affected.

Next, a method of manufacturing the two-dimensional contact type image sensor of this embodiment will be described with reference to FIG. Figure 6
(A)-(e) is process sectional explanatory drawing which shows the manufacturing method of the two-dimensional contact image sensor of a present Example. First, on the substrate 1 made of glass or the like, chromium (Cr1) is deposited by DC sputtering to a thickness of about 750 Å, and patterned by photolithography and etching to form the gate electrode 18 of the thin film transistor.
Are formed (see FIG. 6A).

After BHF treatment and alkali cleaning,
Silicon nitride (b-SiNx) as the gate insulating layer 19 has a film thickness of about 3000 angstroms, and hydrogenated amorphous silicon (a-Si: H) as the semiconductor active layer 20 has a film thickness of about 500 angstroms by the plasma CVD method. Then, silicon nitride (t-SiNx) as the top insulating layer 21 is continuously deposited with a film thickness of about 1500 angstrom without breaking the vacuum. Then, the top insulating layer 21 is formed by patterning t-SiNx by photolithography using backside exposure and etching.
Are formed (see FIG. 6B).

The conditions for depositing b-SiNx are as follows:
The substrate temperature is 300 to 400 ° C., the SiH ₄ and NH ₃ gas pressure is 0.1 to 0.5 Torr, and the SiH ₄ gas flow rate is 10 to 10.
50 sccm, NH ₃ gas flow rate 100~300sccm, RF
The power is 50 to 200W. The conditions for depositing a-Si: H are: substrate temperature of 200 to 300 ° C., SiH ₄ gas pressure of 0.1 to 0.5 Torr, and SiH ₄ gas flow rate of 1.
00-300 sccm, RF power 50-200W. The condition for depositing t-SiNx is that the substrate temperature is 200
~ 300 ℃, SiH ₄ and NH ₃ gas pressure 0.1 ~
0.5 Torr, SiH ₄ gas flow rate 10 to 50 sccm, RF
The power is 50 to 200W.

Next, n + a-Si: H as the ohmic contact layer 22 is deposited by P-CVD to a thickness of about 1000 angstroms, and the source / drain electrodes of the TFT and the photodiode are formed thereon. A second chromium (Cr2) layer to be the metal electrode 15 is deposited by DC magnetron sputtering to a thickness of about 1500 angstroms, and a-Si: H to be the photoconductive layer 16 of the photodiode is further deposited thereon. 130 by P-CVD method
A film having a film thickness of about 00 angstrom is formed, and ITO serving as the transparent electrode 17 is formed on the film with a film thickness of about 600 angstrom by the DC magnetron sputtering method.
At this time, alkali cleaning is performed before each film deposition. And IT by photolithography and etching
O is patterned and a-Si: H is patterned by dry etching using the same resist pattern to form the transparent electrode 17 of the photodiode and the photoconductive layer 16 (see FIG. 6C).

Here, the second chromium layer (Cr2) is a
-Si: H acts as a stopper during dry etching and remains without patterning. In addition, since the side etching is greatly included in the a-Si: H during the dry etching, the ITO is etched again before the resist is peeled off.

The conditions for depositing the a-Si: H film are as follows: the substrate temperature is 170 to 250 ° C., and the SiH ₄ gas pressure is 0.3.
~ 0.7 Torr, SiH ₄ gas flow rate 150 ~ 300sc
cm, and RF power is 100 to 200 W. Above ITO
The conditions for forming the film are as follows: substrate temperature is room temperature, Ar and O ₂ gas pressure is 1.5 × 10 ⁻³ Torr, and Ar gas flow rate is 100.
˜150 sccm, O ₂ gas flow rate is 1˜2 sccm, and DC power is 200˜400 W.

Then, the second chromium layer (Cr2) is patterned by photolithography and etching to form the metal electrode 15 of the photodiode, the source electrode 23 and the drain electrode 24 of the TFT, and then the same resist. The ohmic contact layer 22 is formed by etching n + a-Si: H using the pattern. Further, b-SiNx is patterned by photolithography and etching to form a gate insulating layer 19 of the TFT (see FIG. 6D).

Next, polyimide is applied with a film thickness of about 11500 angstroms so as to cover the entire substrate 1, and after prebaking, contact holes are opened by photolithography and etching to form an interlayer insulating layer 25. After this, a Descum of exposing to plasma is performed to completely remove the polyimide remaining in the contact holes.
Then, aluminum (Al) is deposited by DC magnetron sputtering to a thickness of about 15000 angstroms, and patterned by photolithography and etching to form each data layer 9, each wiring layer such as the bias line 11 also serving as a light shielding layer wiring. Are formed (see FIG. 6E).

After that, a passivation layer made of polyimide is formed so as to cover the entire image sensor, and a glass substrate, a driving IC and the like are mounted on a mounting printed board, and wire bonding and assembly are performed to form an image sensor. It is a thing.

According to the two-dimensional contact type image sensor of this embodiment, the bias line 11 of the light receiving element 2 is shared with the wiring of the light shielding layer of the thin film transistor 6, and the bias line 11 of the semiconductor active layer 20 of the thin film transistor 6 is used. Since it is formed so as to cover the upper part of the channel region 20 ', the area of the light receiving portion of the light receiving element 2 in one pixel can be formed large, and the sensitivity of the image sensor can be improved without lowering the resolution. There is an effect that can be.

Further, in the two-dimensional contact type image sensor of this embodiment, since aluminum (Al) having a small sheet resistance is used as the material of the bias line 11, there is an effect that the power consumption of the image sensor can be reduced.

Furthermore, since the metal electrode of the light receiving element 2 is used as an individual electrode for each pixel and the bias line 11 is formed in the upper layer and is connected to the metal electrode 15, the gate line 10 and the bias line 11 of the thin film transistor 6 are connected. Also at the intersection with and, because of the structure in which a plurality of insulating layers and the like are provided between the gate line 10 and the bias line 11, the capacitance formed at the intersection can be reduced, and therefore the gate line 10 There is an effect that an adverse effect on the propagating gate pulse (an adverse effect that the pulse waveform is broken) can be prevented and good switching characteristics of the thin film transistor can be realized.

[0045]

According to the present invention, since the wiring of the light shielding layer for shielding the channel region of the thin film transistor and the bias line of the light receiving element are commonly used as the two-dimensional contact type image sensor, the bias line is provided above the thin film transistor. With the structure to be formed, there is an effect that the area of the photoelectric conversion part can be increased without enlarging the pixel area, and the sensitivity can be improved without lowering the resolution, and the bias line and the gate line of the thin film transistor Since the distance in the vertical direction can be increased, the capacitance formed at the intersection of the bias line and the gate line is reduced, which has the effect of reducing the influence on the gate pulse and improving the switching characteristics of the thin film transistor. Furthermore, if the bias line is made of aluminum having a low sheet resistance, power consumption can be reduced. There is a kill effect.

[Brief description of drawings]

FIG. 1 is an explanatory plan view of one pixel of a two-dimensional contact image sensor according to an embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view of a portion AA ′ in FIG.

FIG. 3 is an equivalent circuit diagram of the two-dimensional contact image sensor of this embodiment.

FIG. 4 is one of the two-dimensional contact type image sensor of this embodiment.
It is an equivalent circuit diagram of a pixel.

FIG. 5 is an ID-VG characteristic diagram of a thin film transistor of the two-dimensional contact image sensor of this example.

FIG. 6 is a process cross-sectional explanatory view showing the method of manufacturing the two-dimensional contact image sensor of this embodiment.

FIG. 7 is a schematic cross-sectional explanatory view of a conventional one-dimensional contact image sensor.

FIG. 8 is an equivalent circuit diagram of a two-dimensional contact image sensor.

FIG. 9 is an explanatory plan view of one pixel of a conventional two-dimensional contact image sensor.

10 is a cross-sectional explanatory view of a BB ′ portion of FIG.

FIG. 11 is a plan view of another conventional two-dimensional contact image sensor.

12 is a cross-sectional explanatory view of a CC ′ portion of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Light receiving element, 3 ... Light collecting part, 4 ... Transparent protective film, 5 ... Original, 6 ... Thin film transistor, 7 ... Pixel, 9 ... Data line, 10 ... Gate line, 11 ... Bias line, 12 ... Shading Layer, 13 ... Analog multiplexer, 14 ... Shift register, 15 ... Metal electrode, 1
6 ... Photoconductive layer, 17 ... Transparent electrode, 18 ... Gate electrode,
19 ... Gate insulating layer, 20 ... Semiconductor active layer, 2
0 '... Channel region, 21 ... Top insulating layer, 22 ...
Ohmic contact layer, 23 ... Source electrode, 24 ...
Drain electrode, 25 ... Interlayer insulating layer, 26 ... Wiring layer

Claims (1)

[Claims] 1. A two-dimensional contact type image sensor in which pixels, each comprising a light-receiving element and a thin film transistor as a switching element connected to the light-receiving element, are arranged in a two-dimensional matrix on a substrate. A two-dimensional contact type image sensor characterized in that a wiring of a light shielding layer for shielding an area and a bias line for supplying a constant voltage to the light receiving element are commonly used.