JPH04257262A - Image sensor - Google Patents

Abstract

PURPOSE:To prevent short circuit between an interconnection and an electrode by forming a light shielding layer having both an insulating property and a light shielding property so as to cover a layer-to-layer insulated film and by making contact holes in the layer-to-layer insulated film and the light shielding layer for forming an interconnection to be connected to a drain electrode and a source electrode. CONSTITUTION:A silicon nitride film which serves as top insulated film 29, an n<+> amorphous silicon hydride layer, that is, N<+>a-Si:H layer, which serves as ohmic contact layer 28 are so formed as to face a gate electrode 25. Then, chrome layers are formed which serve as a drain electrode 41 and a source electrode 42. Moreover, a polyimide layer is formed which serves as layer to- layer insulated film 40 and a germanium oxide film which serves as light shielding layer 44 is so formed as to cover the upper part of TFT and aluminum interconnections 30a and 30b which are to be connected to the drain electrode 41 and the source electrode 42 are laminated in order.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor used as a reading section of a facsimile machine, an image scanner, etc., and more particularly to an image sensor that can reduce short-circuits between lead wires from each electrode and other electrodes. .

0002

2. Description of the Related Art Conventional image sensors, particularly contact type image sensors, project image information of a document or the like on a one-to-one basis and convert it into an electrical signal. In this case, the projected image is divided into a large number of pixels (light receiving elements), and the charge generated in each light receiving element is transferred to a thin film transistor switching element (T
FT) is used to temporarily accumulate in the wiring capacitance of multilayer wiring in specific blocks, and generate electrical signals from several hundred KHz to several M
There is a TFT-driven image sensor that sequentially reads data in a time-series manner at a speed up to Hz. This TFT-driven image sensor can be read by a single driving IC due to the operation of the TFT.
This is to reduce the number of C's.

[0003] TFT-driven image sensors include, for example,
As its equivalent circuit diagram is shown in FIG.
A plurality of thin film transistors Ti,j corresponding to 11
Charge transfer unit 1 consisting of (i=1 to N, j=1 to n)
2 and multilayer wiring 13.

The light-receiving element array 11 is divided into N (64) blocks of light-receiving element groups, and the n (38) light-receiving elements 11' forming one light-receiving element group are photodiodes Pi,j. It can be equivalently represented by (i=1 to N, j=1 to n). Each light receiving element 11' is connected to the drain electrode of each thin film transistor Ti,j. The source electrode of the thin film transistor Ti,j is connected to the multilayer wiring 1 formed in a matrix.
3, each light receiving element group is connected to n common signal lines 14, and the common signal line 14 is further connected to a driving IC 15.

A gate pulse generating circuit 16 is connected to the gate electrode of each thin film transistor Ti,j so as to be conductive for each block. After the photocharges generated in each photodetector 11' are accumulated in the parasitic capacitance of the photodetector and the overlap capacitance between the drain and gate of the thin film transistor for a certain period of time, the photocharges generated in each photodetector 11' are transferred block by block using the thin film transistor Ti,j as a charge transfer switch. are sequentially transferred and stored in the wiring capacitance Ci (i=1 to n) of the multilayer wiring 13.

That is, the gate pulse φG1 from the gate pulse generation circuit 16 turns on the thin film transistors T1,1 to T1,n of the first block, and the first
Charges generated in each light-receiving element 11'' of the block and accumulated in parasitic capacitances are transferred and accumulated in each interconnect capacitor Ci.Then, the potential of each common signal line 14 is changed by the charges accumulated in each interconnect capacitor Ci. changes, and this voltage value is applied to the driving IC.
The analog switches SWi (i=1 to n) in 15 are turned on sequentially to extract the signal to the output line 17 in time series.

[0007] Then, gate pulses φG2 to φG
n, the thin film transistors T of the second to Nth blocks
By turning on 2,1 to T2,n to TN,1 to TN,n, the charge on the light receiving element side is transferred block by block, and by sequentially reading out the image signal of one line in the main scanning direction of the document. In addition, an image signal of the entire document is obtained by moving the document using a document feeder (not shown) such as a roller and repeating the above operations (see Japanese Patent Laid-Open No. 63-9358).

Next, the specific structure of the light receiving element and the thin film transistor in the conventional image sensor will be explained with reference to FIG. 10, which is a partial cross-sectional view of the light receiving element, the thin film transistor, and the multilayer wiring.

As shown in FIG. 10, a conventional photodetector has a structure in which a chromium (Cr) layer is placed on an insulating substrate 21 made of glass or ceramic, and serves as a common electrode at the bottom of the photodetector 11'.
) etc., and a photoconductive layer 23 made of hydrogenated amorphous silicon (a-Si:H) formed separately for each light receiving element 11' (for each bit), and a photoconductive layer 23 made of hydrogenated amorphous silicon (a-Si:H) formed separately. The upper transparent electrode 24 made of indium tin oxide (ITO) constitutes a sandwich type in which layers are sequentially stacked.

Note that here, the lower metal electrode 22 is formed in a strip shape in the main scanning direction, and the photoconductive layer is formed on the metal electrode 22 by being discretely divided, and the upper transparent electrode 24 is also formed into discrete segments. By dividing the photoconductive layer 23 into individual electrodes, a portion of the photoconductive layer 23 sandwiched between the metal electrode 22 and the transparent electrode 24 constitutes each light receiving element 11', and a collection of these constitutes the light receiving element array 11. is formed. As shown in FIG. 9, a constant voltage VB is applied to the metal electrode 22.

Further, one end of each of the transparent electrodes 24 formed in a discrete manner is connected to one side of a wiring 30a made of aluminum or the like, and the other side of the wiring 30a is connected to the charge transfer section 1.
It is connected to the drain electrode 41 of the second thin film transistor Ti,j.

Further, the structure of a conventional thin film transistor of an image sensor is as shown in FIG. film (SiNx), hydrogenated amorphous silicon (SiNx) as the semiconductor active layer 27
a-Si:H) layer, a silicon nitride film (Si
Nx), n+ hydrogenated amorphous silicon (n+ a-Si:H) layer as ohmic contact layer 28,
Chromium (C) is used as the drain electrode 41 and source electrode 42.
r2) layer, a polyimide layer thereon as an interlayer insulating layer 40, and further above that a light-shielding metal layer 30 of an aluminum layer as a light-shielding a-Si:H layer on the wiring layer 30a or the top insulating layer 29. This is a transistor with an inverted staggered structure in which the following layers are sequentially stacked.

The light-shielding metal layer 30 is provided to prevent light from penetrating the a-Si:H layer through the top insulating layer 29 and causing photoelectric conversion. and,
A wiring 30a from the transparent electrode 24 of the light receiving element 11' is connected to the drain electrode 41, and a wiring 30b from the multilayer wiring 13 to the source electrode 42.

Here, the ohmic contact layer 28 has a layer 28a in contact with the drain electrode 41 and the source electrode 4.
2 and a layer 28b in contact with the layer 28b. Further, the chromium (Cr2) layer as the drain electrode 41 and the source electrode 42 is connected to the ohmic contact layer 28.
28a and 28b, respectively. The chromium (Cr2) layer is formed of the wirings 30a, 3
This serves to prevent damage during deposition of the 0b aluminum layer by vapor deposition or sputtering, and to maintain the n+a-Si:H characteristics of the ohmic contact layer 28.

[0015]

However, in the conventional image sensor described above, a metal layer such as aluminum (Al) is used as the light-shielding metal layer 30 of the TFT. Pull-out wiring 3
0a or the lead wire 30b of the drain electrode 41 are too close to each other, there is a problem that a short circuit occurs between the source electrode 42 and the drain electrode 41 via the light-shielding metal layer 30.

Furthermore, when the light-shielding metal layer 30 is formed of a layer of aluminum (Al), the light-shielding metal layer 30
The extraction wiring 30a, 30 of both drain and source electrodes
It is necessary to form it so that it does not contact b, that is, to have a gap, and there is a problem that the light shielding property becomes insufficient due to the gap.

Furthermore, an interlayer insulating layer 40 of the thin film transistor
Since the film thickness tends to be thinner near the edges of both the source and drain electrodes, short circuits may occur between the lead wires 30a and 30b of both the drain and source electrodes and the gate electrode 25. There is also a problem in that short circuits occur when there are pinholes in the interlayer insulating layer 40.

Furthermore, in the light receiving element section, since the thickness of the interlayer insulating layer 40 tends to become thinner near the pattern edge of the light receiving element, the wiring 30a drawn out from the transparent electrode 24 of the light receiving element and the light receiving element are connected to each other. There is a problem that a short circuit may occur between the metal electrode 22 and a short circuit also occurs when a pinhole exists in the interlayer insulating layer 40.

The present invention has been made in view of the above circumstances, and by forming a film having light-shielding and insulating properties on the interlayer insulating layer of the image sensor, the lead-out portions (draw-out wiring) from each electrode are formed. An object of the present invention is to provide an image sensor that can reduce short circuits that occur between the electrode and other electrodes.

[0020]

[Means for Solving the Problems] The invention according to claim 1 for solving the problems of the conventional example is an image sensor having a thin film transistor element having a gate electrode, a drain electrode, and a source electrode. an interlayer insulating layer formed to cover the drain electrode and the source electrode; a light shielding layer formed to have insulation and light shielding properties so as to cover the interlayer insulating layer; and the interlayer insulating layer. A contact hole is formed in the light shielding layer to provide a wiring connected to the drain electrode and a wiring connected to the source electrode.

[0021] The invention according to claim 2 for solving the problems of the conventional example has a gate electrode, a drain electrode and a source.
An image having a thin film transistor element with a ground electrode.
In the sensor, an interlayer insulating layer formed to cover the drain electrode and the source electrode, upper and lower layer portions covering the interlayer insulating layer have an insulating property, and an intermediate layer portion has a light shielding property and an insulating property. A contact hole is formed in the interlayer insulating layer and the light shielding layer, and the wiring is connected to the drain electrode and the source electrode. It is characterized by the provision of wiring.

[0022] The invention according to claim 3 for solving the problems of the conventional example has a gate electrode, a drain electrode and a source.
An image having a thin film transistor element with a ground electrode.
an interlayer insulating layer formed to cover the drain electrode and the source electrode, a first light-shielding layer formed to have insulation so as to cover the interlayer insulating layer, and the first light-shielding layer. a second light-shielding layer formed to have light-shielding properties and insulation properties on the light-shielding layer; a third light-shielding layer formed to have insulation properties on the second light-shielding layer; and the interlayer insulating layer. Contact holes are formed in the first light-shielding layer, the second light-shielding layer, and the third light-shielding layer to provide a wiring connected to the drain electrode and a wiring connected to the source electrode. It is characterized by

The invention as set forth in claim 4 for solving the problems of the conventional example provides an image sensor having a light receiving element in which a metal electrode, a photoconductive layer, and a transparent electrode are sequentially laminated on a substrate. an interlayer insulating layer formed to cover an end of the light receiving element, and a light shielding layer having insulation and light shielding properties formed via the interlayer insulating layer to cover an end of the light receiving element;
The invention is characterized in that a contact hole is formed in the interlayer insulating layer and the light shielding layer to provide wiring connected to the transparent electrode.

The invention as set forth in claim 5 for solving the problems of the conventional example includes a light-receiving element in which a metal electrode, a photoconductive layer, and a transparent electrode are sequentially laminated on a substrate, a gate electrode, a drain electrode, and In an image sensor having a thin film transistor element having a source electrode, an interlayer insulating layer formed to cover the transparent electrode of the light receiving element and the drain electrode and the source electrode of the thin film transistor element; A light-shielding layer having insulation and light-shielding properties is formed to cover an end of the light-receiving element in the light-receiving element portion, and to cover the interlayer insulating layer in the thin-film transistor element portion, and the interlayer insulating layer and the light-shielding layer. contact hole in layer
The method is characterized in that a wiring is provided to form a hole and connect to the transparent electrode, a wiring to connect to the drain electrode, and a wiring to connect to the source electrode.

[0024]

According to the first aspect of the invention, in the thin film transistor portion, a light shielding layer having insulation and light shielding properties is formed to cover the interlayer insulating layer, and a contact hole is formed in the interlayer insulating layer and the light shielding layer. Since the image sensor is equipped with wiring connected to the drain electrode and the source electrode, short-circuits between the wiring connected to the drain electrode and the wiring connected to the source electrode are prevented, and both Short-circuits between the wiring and the gate electrode can also be prevented.

According to the second aspect of the invention, in the thin film transistor portion, the chemical composition is changed so that the upper and lower layers have insulating properties so as to cover the interlayer insulating layer, and the intermediate layer has light blocking properties and insulating properties. The image sensor has a light-shielding layer formed, a contact hole formed in the interlayer insulating layer and the light-shielding layer, and wiring connected to the drain electrode and source electrode. It is possible to prevent short-circuits between the wiring connected to the base electrode and the gate electrode, and also to prevent short-circuits between both wirings and the gate electrode.

According to the third aspect of the invention, in the thin film transistor portion, the first light-shielding layer having an insulating property covers the interlayer insulating layer, the second light-shielding layer having a light-shielding property and an insulating property, and an insulating layer. contact holes are formed in the interlayer insulating layer, the first light-shielding layer, the second light-shielding layer, and the third light-shielding layer to form a drain electrode and a source electrode. Since the image sensor is equipped with wiring connected to the drain electrode and the source electrode, it is possible to prevent short-circuits between the wiring connected to the drain electrode and the wiring connected to the source electrode, and to connect both wiring and the gate electrode.
Short-circuits with the short electrode can also be prevented.

According to the fourth aspect of the invention, in the light-receiving element portion, a light-shielding layer having insulation and light-shielding properties is formed on the interlayer insulating layer so as to cover the end of the transparent electrode, and the interlayer insulating layer and the light-shielding layer are bonded together. Since the image sensor has a contact hole formed in the layer and a wiring connected to the transparent electrode, short circuit between the wiring connected to the transparent electrode and the metal electrode can be prevented.

According to the fifth aspect of the invention, in the image sensor, an interlayer insulating layer is provided to cover the end of the transparent electrode in the light receiving element portion, and an interlayer insulating layer is provided to cover the entire thin film transistor portion. Form a light-shielding layer with insulation and light-shielding properties through the interlayer insulating layer and the light-shielding layer, connect to the transparent electrode by forming a contact hole in the interlayer insulating layer and the light-shielding layer, connect to the drain electrode, and connect to the source electrode. Since the image sensor is equipped with wiring that connects to the transparent electrode, it is possible to prevent short circuits between the wiring that connects to the transparent electrode and the metal electrode in the light receiving element part, and the wiring that connects to the drain electrode and the metal electrode in the thin film transistor part. It is possible to prevent short-circuits between the wiring connected to the source electrode and the gate electrode, as well as between both wirings and the gate electrode.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory plan view of a light receiving element and a thin film transistor of an image sensor according to an embodiment of the present invention, and FIG. 2 is an explanatory cross-sectional view taken along the line AA' in FIG. Figure 9
Components having the same configuration as those in FIG. 10 will be described using the same reference numerals.

The image sensor has a circuit similar to the equivalent circuit shown in FIG. 9, and includes n sandwich-type light receiving elements (photodiodes P) arranged in parallel on an insulating substrate such as glass. 11' is taken as one block, and the light receiving element array 11 (P1, 1
~PN,n), a charge transfer section 12 of the thin film transistor (T1,1 ~TN,n) connected to each light receiving element 11', a matrix-shaped multilayer wiring 13, and a charge transfer section 12 to multilayer wiring 13. n common signal lines 14 corresponding to each light receiving element in the block and an analog switch S in the driving IC 15 to which the common signal line 14 is connected.
It is composed of W1 to SWn.

As shown in FIGS. 1 and 2, the light-receiving element 11' is made of chromium (Cr), which serves as a common electrode at the lower part of the light-receiving element 11', on an insulating substrate 21 made of glass or ceramic.
) etc., and a photoconductive layer 23 made of hydrogenated amorphous silicon (a-Si:H) formed separately for each light receiving element 11' (for each bit), and a photoconductive layer 23 made of hydrogenated amorphous silicon (a-Si:H) formed separately. The upper transparent electrode 24 made of indium tin oxide (ITO) constitutes a sandwich type in which layers are sequentially stacked.

Here, the lower metal electrode 22 is formed in a strip shape in the main scanning direction, and the photoconductive layer 2 is formed on the metal electrode 22.
3 is formed by discretely dividing the photoconductive layer 23 into the metal electrode 22 and the transparent electrode 2.
The portion sandwiched between 4 and 4 constitutes each light-receiving element 11', and a collection thereof forms the light-receiving element array 11. A constant voltage VB is applied to the metal electrode 22.

In this way, the photoconductive layer 23 and the transparent electrode 24
The reason why the a-Si:H photoconductive layer 23 is a common layer is to reduce interference between adjacent electrodes because the common layer causes interference between adjacent electrodes.

Further, one end of each of the transparent electrodes 24 formed in a discrete manner is connected to one side of a wiring 30a made of aluminum or the like, and the other side of the wiring 30a is connected to the charge transfer section 1.
It is connected to the drain electrode 41 of the second thin film transistor Ti,j.

In the light receiving element 11', it is also possible to use CdSe (cadmium selenium) or the like as the photoconductive layer instead of hydrogenated amorphous silicon. Furthermore, a-Si:H, pin
may be used, or a-SiC or a-SiGe may be used. Furthermore, although the light receiving element 11' is a photodiode, it may also be a photoconductor or a phototransistor.

Further, as shown in FIGS. 1 and 2, the thin film transistor constituting the charge transfer section 12 is connected to the substrate 21.
A chromium (Cr1) layer as a gate electrode 25 and a gate electrode 25 are formed on top of the gate electrode 25.
a silicon nitride film (SiNx) as the insulating layer 26;
A hydrogenated amorphous silicon (a-Si:H) layer as the semiconductor active layer 27, a silicon nitride film as the top insulating layer 29 provided to face the gate electrode 25, and an n+ as the ohmic contact layer 28. a hydrogenated amorphous silicon (n+ a-Si:H) layer, a chromium (Cr2) layer as a drain electrode 41 and a source electrode 42,
On top of that, a polyimide layer as an interlayer insulating layer 40, a TFT
Germanium oxide (G) of the light shielding layer 44 covers the upper part.
This transistor has an inverted staggered structure in which aluminum (Al) wirings 30a and 30b connected to a drain electrode 41, a drain electrode 41, and a source electrode 42 are sequentially laminated.

The light shielding layer 44 is provided to prevent light from penetrating the a-Si:H layer through the top insulating layer 29 and causing photoelectric conversion. Here, the ohmic contact layer 28 includes a layer 28a that contacts the drain electrode 41 and a layer 28b that contacts the source electrode 42.
It is divided into two parts. In addition, the drain electrode 41
A chromium (Cr2) layer serving as a source electrode 42 is formed to cover portions 28a and 28b of the ohmic contact layer 28, respectively. The above chromium (Cr
2) The layer prevents damage during deposition of the aluminum layer of the wirings 30a and 30b by vapor deposition or sputtering, and
It plays a role of maintaining the characteristics of the n+ a-SiH layer of the microcontact layer 28.

The light receiving element 1 is connected to the drain electrode 41.
The wiring 30a from the transparent electrode 24 of 1' is connected, and the aluminum wiring 30b to the multilayer wiring 13 is connected to the source electrode 42. The wiring 30b is connected to the lower signal line 31 of the multilayer wiring 13, and a contact is made. It is configured to be connected to the upper signal line 32 through a hole 35. Further, the same effect can be obtained even if another material such as poly-Si is used for the semiconductor active layer 27.

The GeOx film of the light-shielding layer 44 is formed by gradually controlling the gas partial pressure in the sputtering atmosphere so as to have a composition gradient in the film thickness direction. By increasing the amount of GeOx at the beginning and end of the process and decreasing it in the middle, the light-shielding layer 4
The lower layer portion and the upper layer portion of No. 4 are formed to have insulating properties, and the intermediate layer is formed to have light blocking properties.

Next, a method of manufacturing the light receiving element 11' portion and the thin film transistor (TFT) portion will be explained.

First, a chromium (Cr1) layer, which will become the gate electrode 25 of the thin film transistor, is formed on an inspected and cleaned insulating substrate 21 such as glass by DC sputtering to a thickness of about 750 angstroms at a temperature of about 150°C. A film is deposited.

Next, the chromium (Cr1) layer is patterned by a photolithography process and an etching process using a mixture of cerium ammonium nitrate, perchloric acid, and water to form a pattern for the gate electrode 25. Peel off the resist.

Then, alkaline cleaning is performed to remove the gate insulating film 26 of the thin film transistor, the semiconductor active layer 27 above it, and the top insulating layer 2 above it on the chromium pattern.
9, a silicon nitride film (SiNx) is
a hydrogenated amorphous silicon (a-Si:H) layer with a thickness of about 500 angstroms, and a silicon nitride (SiNx) layer with a thickness of about 500 angstroms.
A film of about 1500 angstroms is sequentially deposited by plasma CVD (P-CVD) without breaking the vacuum. By continuously depositing the films without breaking the vacuum, contamination of each interface can be prevented, and the characteristics of the TFT can be stabilized.

The insulating film of the gate insulating layer 26 (b-SiNx
) is formed by P-CVD, the substrate temperature is 300℃.
At ~400°C, the gas pressure of SiH4 and NH3 is 0.
At 1 to 0.5 Torr, the SiH4 gas flow rate is 10 to 0.5 Torr.
At 50 sccm, the NH3 gas flow rate is 100 to 300
sccm, and the RF power is 50-200W.

The a-Si:H film of the semiconductor active layer 27 is made of P-
The conditions for forming by CVD are that the substrate temperature is approximately 200-300℃.
℃, the gas pressure of SiH4 is 0.1~0.5OTor
r, the SiH4 gas flow rate is 100-300 sccm, and the RF power is 50-200W.

The insulating film of the top insulating layer 29 (t-SiNx
) by P-CVD is that the substrate temperature is approximately 20°C.
At 0 to 300℃, the gas pressure of SiH4 and NH3 is 0.
．． At 1 to 0.5 Torr, the SiH4 gas flow rate is 10
~50 sccm, NH3 gas flow rate is 100~30 sccm
At 0 sccm, the RF power is 50-200W.

Next, in order to form a pattern of the top insulating layer 29 in a shape corresponding to the gate electrode 25, the top insulating layer 29 is formed by a photolithography process and an etching process using a mixed solution of HF and NH4F. Forming the pattern of layer 29.

[0048] Furthermore, BHF processing is performed, and then
n+ type a-Si:H as the contact layer 28
The film was heated to a thickness of about 1000 angstroms at about 250°C using a P-CVD method using a mixed gas of SiH and PH3.
A film forms at a temperature of about

Next, the metal electrode 2 at the bottom of the light receiving element 11'
2 and a second Cr (Cr2) layer which will become the drain electrode 41 and source electrode 42 of the TFT is deposited to a thickness of about 1500 angstroms by DC magnetron sputtering.

Next, the photoconductive layer a of the light receiving element 11' is
-Si:H is deposited to a thickness of about 13,000 angstroms by P-CVD, and ITO, which will become the transparent electrode 24 of the light receiving element 11', is deposited by DC magnetron sputtering to a thickness of about 13,000 angstroms.
The film is deposited to a thickness of about 0.00 angstroms. At this time,
Alkaline cleaning is performed before each film deposition.

The a-Si:H film of the photoconductive layer 23 is made of P-
The conditions for forming by CVD are that the substrate temperature is 170 to 250°C.
Then, the SiH4 gas pressure is 0.3 to 0.7 Torr, the SiH4 gas flow rate is 150 to 300 sccm,
RF power is 100-200W.

Further, the conditions for forming the above-mentioned ITO by DC sputtering are that the substrate temperature is room temperature, the Ar and O2 gas pressure is 1.5 x 10-3 Torr, and the Ar gas flow rate is 100
~150sccm, O2 gas flow rate is 1~2sccm
The DC power is 200 to 400W.

Thereafter, in order to form individual electrodes of the transparent electrode 24 of the light receiving element 11', ITO is patterned by a photolithography process and an etching process using a mixed solution of ferric chloride and hydrochloric acid. Next, the a-Si:H layer of the photoconductive layer 23 is coated with CF4 and O2 using the same resist pattern.
Patterning is performed by dry etching using a mixed gas of Here, the chromium (Cr2) layer of the metal electrode 22 serves as a stopper during dry etching of a-Si:H, and remains without being patterned. During this dry etching, the photoconductive layer 23
Since side etching is large in the a-Si:H layer, ITO is etched again before removing the resist. Then, the ITO is further etched from the back side around the periphery, and is formed to have the same size as the a-Si:H layer of the photoconductive layer 23.

Next, using a photolithographic mask to form patterns for the chromium (Cr2) layer of the metal electrode 22 of the light receiving element 11' and the chromium (Cr2) layer of the source electrode 42 and drain electrode 41 of the TFT, A resist pattern is formed by exposure and development using a photolithography method, patterning is performed by an etching process using a mixture of cerium ammonium nitrate, perchloric acid, and water, and the resist is removed. In this patterning, the metal electrode 22, the source electrode 4
2 and a drain electrode 41 pattern are formed.

Next, when dry etching is performed using a mixed gas of HF4 and O2, the parts without Cr2 and SiNx are etched, and the patterns of the a-Si:H layer and the n+ type a-Si:H layer are etched. It is formed. As a result, an n+ type a-Si:H layer and a-Si:
H layer, and the n of the ohmic contact layer 28 of the TFT.
+ type a-Si: H layer portion and a- of semiconductor active layer 27
The Si:H layer portion is etched. In this way,
A pattern of the semiconductor active layer 27 is formed, and the ohmic contact layer 28 is also divided into a portion 28a that contacts the drain electrode 41 and a portion 28 that contacts the source electrode 42.
Pattern b is formed.

Next, in order to form a pattern for the gate insulating layer 26 of the TFT, the b-SiNx film was heated with HF4 and O2.
A pattern is formed by a photolithographic etching process using a mixed gas of 2.

Then, in order to form the interlayer insulating layer 40 so as to cover the entire image sensor, polyimide is
The film is coated to a thickness of about 0.00 angstroms, prebaked at about 160° C., patterned using a photolithographic etching process, and baked again.

Next, in the TFT portion, the interlayer insulating layer 4
A light shielding layer 44 made of a germanium oxide (GeOx) film with a thickness of about 2000 angstroms covers the
form.

This light shielding layer 44 is formed by RF reactive sputtering, using germanium (
Ge), an Ar+O2 mixed gas is used as the sputtering atmosphere. This GeOx film is formed by gradually controlling the gas partial pressure of the sputtering atmosphere so that it has a composition gradient in the film thickness direction, and x of GeOx is 1.0≦x≦1.5 near the substrate side interface. 0 near the center of the membrane.
The composition is formed so as to gradually change so that 1≦x≦1.0 and further 1.0≦x≦1.5 near the interface on the opposite side to the substrate side.

That is, when forming the lower layer and the upper layer of the light shielding layer 44, the amount of oxygen O2 is increased to form the light shielding layer 44.
When forming the intermediate layer portion of No. 4, the amount of oxygen O2 is reduced. As a result, the upper and lower layers of the light-shielding layer 44, which have a large amount of O2, have an insulating property, and the intermediate layer, which has a small amount of O2 and a large amount of Ge, becomes colored and has a light-blocking property.

[0061] Then, this light shielding layer 44 and interlayer insulating layer 40
is patterned in a photolithographic etching process, and in the light receiving element 11', the contact part that supplies power to the metal electrode 22 and the contact part that connects the wiring from the transparent electrode 24 to the drain electrode 41, and in the TFT, the contact part that supplies power to the metal electrode 22, and the contact part that connects the wiring from the transparent electrode 24 to the drain electrode 41, and in the TFT, the contact part that supplies power to the metal electrode 22, and the contact part that connects the wiring from the transparent electrode 24 to the drain electrode 41, and the A contact portion connecting the wiring from the transparent electrode 24 to the drain electrode 41 and a contact portion connecting the wiring from the source electrode 42 to the multilayer wiring 13 are formed.

After this, in order to completely remove polyimide and the like remaining in the contact portion, descum is performed by exposing the contact portion to plasma using O2.

Next, a film of aluminum (Al) is deposited to a thickness of about 10,000 angstroms at a temperature of about 150° C. by DC magnetron sputtering to cover the entire image sensor, and a film is coated with a film to obtain a desired pattern. The resist is patterned and removed using a photolithographic etching process using a mixture of acid, nitric acid, phosphoric acid, and water. As a result, in the light receiving element 11', the wiring portion that supplies power to the metal electrode 22, the transparent electrode 24 to the drain electrode 41
A wiring 30a portion connecting to the multilayer wiring 13 and a wiring 30b portion connecting from the source electrode 41 to the multilayer wiring 13 are formed.

Finally, polyimide as a passivation layer (not shown) is applied to a thickness of about 3 μm, and heated at 125°C.
A prebaking process is performed at a temperature of about 200° C., a pattern is formed by a photolithographic etching process, and a passivation layer is formed by baking again at about 230° C. for 90 minutes. After this, De
Perform scum to remove unnecessary remaining polyimide.

According to the image sensor of this embodiment, TF
In the T portion, a light-shielding layer 44 of a GeOx film having upper and lower layers having insulating properties and an intermediate layer having light-shielding and insulating properties is formed so as to cover the interlayer insulating layer 40 on the top of the TFT, and the interlayer insulating layer 4
0 and the light-shielding layer 44, the wiring 30a from the transparent electrode 24 of the light receiving element 11' is connected to the drain electrode 41, and the wiring 30b to the multilayer wiring 13 is connected to the source electrode 42. Therefore, if the light-shielding metal layer was formed of the same aluminum layer as the conventional wirings 30a and 30b, a short could occur between the drain and source electrodes through the light-shielding metal layer. However, the light shielding layer 44 has the effect of preventing short circuits between the drain and source electrodes and also maintaining light shielding properties. Furthermore, near the edges of thin film transistors,
Since the insulating light shielding layer 44 is formed on the interlayer insulating layer 40, the drain/source electrode lead wiring 3
This has the effect of preventing short circuits between 0a, 30b and the gate electrode 25.

As another example, as shown in the cross-sectional view of FIG.
Even if it is formed to cover the FT, short circuit between the drain and source can be prevented and light shielding properties can be maintained.

FIG. 4 is an explanatory cross-sectional view of a thin film transistor (TFT) portion of another embodiment of the present invention. In this other embodiment, the light shielding layer has a three-layer structure,
A first light shielding layer 44a and a second light shielding layer 44 from the substrate 21 side.
b, the third light shielding layer 44c, the first light shielding layer 44a
and the third light-shielding layer 44c are each made of Ge2O3 with a film thickness of about 500 angstroms, and the second light-shielding layer 4
4b is GeOx (x of GeOx is 0.1≦x
≦1.0).

First light shielding layer 44a and third light shielding layer 44c
has an insulating property, and the second light-shielding layer 44b has a light-shielding property and an insulating property.As shown in FIG. Then, contact holes are formed to connect the wirings 30a and 30.
b is connected to the drain electrode 41 and source electrode 42, so the wiring 30 connected to the drain electrode 41
It is possible to prevent a short circuit between the wiring 30b connected to the source electrode 42 and the wiring 30b connected to the source electrode 42, and it is also possible to maintain the light-shielding property above the TFT. Also, near the edges of the thin film transistor, the interlayer insulating layer 40
A first light-shielding layer 44a having insulation properties, a second light-shielding layer 44b having light-shielding properties, and a third light-shielding layer 4 having insulation properties thereon.
4c is formed by sequentially stacking the drain/source electrode lead wires 30a, 30b and the gate electrode 2.
This has the effect of preventing short-circuits with 5.

As a further example, as shown in the cross-sectional diagram of FIG. By sequentially forming the second light-shielding layer 44b having an insulating property and the third light-shielding layer 44c having an insulating property, short circuits between the source and drain can be prevented and light-shielding properties can be maintained.

Further, another embodiment will be explained using FIGS. 6, 7 and 8. 6 is a cross-sectional explanatory diagram of an image sensor of another embodiment, FIG. 7 is a plan explanatory diagram of a light receiving element portion of this another embodiment, and FIG. 8 is a cross-sectional explanatory diagram of a section BB' in FIG. 7. It is.

The image sensor of this other embodiment has a light receiving element 11' and a thin film transistor (TFT) on a substrate 21.
A charge transfer section 12 and a multilayer wiring 13 are formed, and the feature is that the TF
Aluminum (Al) connected to the drain electrode 41 of T
The wiring 30a is not formed directly on the polyimide interlayer insulating layer 40, but is made of germanium nitride (GeNx).
It is formed through a light-absorbing (light-shielding) insulating layer 44' of the film.

To explain the light receiving element portion in detail with reference to FIGS. 7 and 8, a light absorbing insulating layer of a GeNx film is formed so as to cover the TFT side end of the light receiving element 11' with an interlayer insulating layer 40 interposed therebetween. A layer 44' is formed, contact holes are provided in the interlayer insulating layer 40 and the light absorbing insulating layer 44',
Al wiring 30a is formed on the light-absorbing insulating layer 44'. At this time, as shown in FIG. 7, if the wiring 30a is formed so that the ends a-b of the wiring 30a do not overlap the ends c-d of the metal electrode 22 in the main scanning direction, the wiring 30a and the metal electrode 22 can be Short circuits can be effectively avoided.

Then, the light-absorbing insulating layer 44' covers the portion of the light-receiving element other than the light-receiving region to define the light-receiving region. This improves MTF.

Similarly, in the TFT portion, a light-absorbing insulating layer 44' of a GeNx film is formed on the interlayer insulating layer 40, and a contact hole is provided in the interlayer insulating layer 40 and the light-absorbing insulating layer 44' to connect the drain. Al wiring 3 on electrode 41
0a has a configuration in which the wiring 30b is connected to the source electrode 42.

The GeNx film of the light-absorbing insulating layer 44' is deposited to a thickness of about 1000 angstroms by sputtering or electron beam evaporation.

[0076] Furthermore, GeNx of the light-absorbing insulating layer 44'
The patterning of the film is performed by applying a resist to unnecessary parts of the GeNx film in advance, forming the GeNx film, and then performing lift-off.

[0077] Note that the GeNx film (x of GeNx is
0.1<x<0.9) and film thickness 1000 angstroms
The light-absorbing insulating layer 44' is made of a material having a resistivity of 105 or more.
It has properties of Ωcm or more, absorption coefficient of 5×10 4 or more, good insulation properties, and good light-shielding properties with transmittance of 5% or less at a wavelength of 550 nm.

The light-absorbing insulating material may also be an incomplete oxide other than GeNx, such as silicon oxide (SiOx
), tantalum oxide (TaOx), or incomplete nitride tantalum nitride (TaNx).

According to this other embodiment, the light receiving element 11'
The lead wiring 30a from the transparent electrode 24 and the metal electrode 2
Since a polyimide interlayer insulating layer 40 and an insulating light-absorbing insulating layer 44' are provided between the pattern edge of No. 2 and the pattern edge of No. 2, short circuits between the wiring 30a and the metal electrode 22 are reduced. Since a light-absorbing insulating layer 44' having a light-shielding property is provided above the TFT, there is no need to form a light-shielding layer of Al, which has the effect of preventing short circuits with both the source and drain electrodes. Furthermore, a light-absorbing insulating layer 44' having an insulating property is formed on the interlayer insulating layer 40 near the edge of the thin film transistor.
This has the effect of preventing short circuits between the drain/source electrode lead wires 30a, 30b and the TFT gate electrode 25.

[0080] Also in the TFT, the light-shielding effect by the light-absorbing insulating layer 44' is large, and a transmittance of 5% or less can be achieved at a wavelength of 550 nm.

[0081]

According to the invention as set forth in claim 1, in the thin film transistor portion, a light shielding layer having insulation and light shielding properties is formed to cover the interlayer insulating layer, and a contact hole is formed in the interlayer insulating layer and the light shielding layer. Since the image sensor has wiring connected to the drain electrode and the source electrode, short circuits between the wiring connected to the drain electrode and the wiring connected to the source electrode can be prevented. , both wiring and game
This also has the effect of preventing short-circuits with the short electrode.

According to the second aspect of the invention, in the thin film transistor portion, the chemical composition is changed so that the upper and lower layers have insulating properties so as to cover the interlayer insulating layer, and the intermediate layer has light blocking properties and insulating properties. The image sensor has a light-shielding layer formed, a contact hole formed in the interlayer insulating layer and the light-shielding layer, and wiring connected to the drain electrode and source electrode. This has the effect of preventing short-circuits between the wiring connected to the source electrode and the gate electrode, and also preventing short-circuits between both wirings and the gate electrode.

According to the third aspect of the invention, in the thin film transistor portion, the first light-shielding layer having an insulating property covers the interlayer insulating layer, the second light-shielding layer having a light-shielding property and an insulating property, and an insulating layer. contact holes are formed in the interlayer insulating layer, the first light-shielding layer, the second light-shielding layer, and the third light-shielding layer to form a drain electrode and a source electrode. Since the image sensor is equipped with wiring connected to the drain electrode and the source electrode, it is possible to prevent short-circuits between the wiring connected to the drain electrode and the wiring connected to the source electrode, and to connect both wiring and the gate electrode.
Short-circuits with the short electrode can also be prevented.

According to the fourth aspect of the invention, in the light-receiving element portion, a light-shielding layer having insulation and light-shielding properties is formed on the interlayer insulating layer so as to cover the end of the transparent electrode, and the interlayer insulating layer and light-shielding Since the image sensor has a contact hole formed in the layer and a wiring connected to the transparent electrode, it is effective in preventing short circuits between the wiring connected to the transparent electrode and the metal electrode. be.

According to the fifth aspect of the present invention, in the image sensor, an interlayer insulating layer is provided to cover the end of the transparent electrode in the light receiving element portion, and an interlayer insulating layer is provided to cover the entire thin film transistor portion. Form a light-shielding layer with insulation and light-shielding properties through the interlayer insulating layer and the light-shielding layer, connect to the transparent electrode by forming a contact hole in the interlayer insulating layer and the light-shielding layer, connect to the drain electrode, and connect to the source electrode. Since the image sensor is equipped with wiring that connects to the transparent electrode, it is possible to prevent short circuits between the wiring that connects to the transparent electrode and the metal electrode in the light receiving element part, and the wiring that connects to the drain electrode and the metal electrode in the thin film transistor part. This has the effect of preventing short-circuits with the wiring connected to the source electrode, and also preventing short-circuits between both wirings and the gate electrode.

Furthermore, by defining the light-receiving region by covering the portion of the light-receiving element other than the light-receiving region with the light-shielding layer, the effects of stray light and the like can be reduced, which has the effect of improving the MTF.

[Brief explanation of the drawing]

FIG. 1 is an explanatory plan view of a part of a light receiving element, a thin film transistor, and a multilayer wiring of an image sensor according to an embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view taken along line AA' in FIG. 1;

FIG. 3 is an explanatory cross-sectional view of a thin film transistor of another example.

FIG. 4 is an explanatory cross-sectional view of a thin film transistor of still another example.

FIG. 5 is an explanatory cross-sectional view of a thin film transistor of still another example.

FIG. 6 is a cross-sectional explanatory diagram of an image sensor according to another embodiment.

FIG. 7 is an explanatory plan view of a light receiving element of another example.

8 is a cross-sectional explanatory diagram of a section BB' in FIG. 7. FIG.

FIG. 9 is an equivalent circuit diagram of an image sensor.

FIG. 10 is an explanatory cross-sectional view of a part of a light receiving element, a thin film transistor, and a multilayer wiring of a conventional image sensor.

[Explanation of symbols]

11 Photo-receiving element array 12 Charge transfer section 13 Multilayer wiring 14 Common signal line 15 Drive IC 16 Gate pulse generation circuit 17 Output line 21　Substrate 22 Metal electrode 23 Photoconductive layer 24 Transparent electrode 25 Gate electrode 26 Gate insulation film 27 Semiconductor active layer 28 Ohmic contact layer 29 Top insulation layer 30 Metal layer for light shielding 31 Lower signal line 32 Upper signal line 35 Contact hole 40 Interlayer insulation layer 41 Drain electrode 42 Source electrode 44 Light shielding layer 44´　　Light-absorbing insulating layer

Claims (5)

[Claims] 1. An image sensor having a thin film transistor element comprising a gate electrode, a drain electrode, and a source electrode, comprising: an interlayer insulating layer formed to cover the drain electrode and the source electrode; A light shielding layer formed to have insulation and light shielding properties so as to cover the interlayer insulating layer, and a contact hole in the interlayer insulating layer and the light shielding layer.
1. An image sensor characterized in that an image sensor is provided with a wiring that forms a channel and connects to the drain electrode, and a wiring that connects to the source electrode. 2. An image sensor having a thin film transistor element having a gate electrode, a drain electrode, and a source electrode, an interlayer insulating layer formed to cover the drain electrode and the source electrode; A light shielding layer formed by changing the chemical composition so that the upper and lower layer portions have insulation properties so as to cover the interlayer insulation layer, and the intermediate layer portion has light shielding properties and insulation properties, and the interlayer insulation layer and the light shielding layer. An image sensor characterized in that a contact hole is formed in a layer to provide a wiring connected to the drain electrode and a wiring connected to the source electrode. 3. An image sensor having a thin film transistor element comprising a gate electrode, a drain electrode, and a source electrode, an interlayer insulating layer formed to cover the drain electrode and the source electrode; a first light-shielding layer formed to have insulation properties so as to cover the interlayer insulating layer; a second light-shielding layer formed to have light-shielding properties and insulation properties on the first light-shielding layer; a third light-shielding layer formed to have an insulating property on the second light-shielding layer; and a contact hole between the interlayer insulating layer, the first light-shielding layer, the second light-shielding layer, and the third light-shielding layer. 1. An image sensor comprising: a wire forming a hole and connecting to the drain electrode; and a wire connecting to the source electrode. 4. An image sensor having a light-receiving element in which a metal electrode, a photoconductive layer, and a transparent electrode are sequentially laminated on a substrate, an interlayer insulating layer formed to cover the light-receiving element, and an end of the light-receiving element. a light-shielding layer having insulation and light-shielding properties formed through the interlayer insulating layer so as to cover the interlayer insulating layer, and a wiring connected to the transparent electrode by forming a contact hole in the interlayer insulating layer and the light-shielding layer. An image sensor characterized by being provided with. 5. An image sensor comprising a light receiving element in which a metal electrode, a photoconductive layer, and a transparent electrode are successively laminated on a substrate, and a thin film transistor element having a gate electrode, a drain electrode, and a source electrode, an interlayer insulating layer formed to cover the transparent electrode of the light receiving element and the drain electrode and the source electrode of the thin film transistor element; In the thin film transistor element portion, a light shielding layer having insulation and light shielding properties is formed to cover the interlayer insulating layer, and a contact hole is formed in the interlayer insulating layer and the light shielding layer to connect to the transparent electrode. An image sensor comprising: a wire connected to the drain electrode; and a wire connected to the source electrode.