JP2011159781A - Photoelectric conversion device, x-ray imaging device, and method of manufacturing photoelectric conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion device that improves connection reliability of external connection terminals and is manufactured through a simple process. <P>SOLUTION: The photoelectric conversion device includes photodiodes 25 and TFTs 24 arranged in a matrix, and also includes a plurality of external connection terminals formed at a peripheral part, wherein each photodiode includes a first electrode 251 connected to a TFT 24 and a second electrode 252 connected to a bias line 23, which is electrically connected to an external connection terminal for bias line. Bias lines 23 are made of transparent conductive metal oxide, formed over the entire light incident surface of the photoelectric conversion device, and extended to the external connection terminals for bias line to be disposed on top sides of the external connection terminals for bias line. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a photoelectric conversion device, an X-ray imaging device, and a method for manufacturing a photoelectric conversion device.
More specifically, the present invention relates to a photoelectric conversion device in which the reliability of electrical connection between the photoelectric conversion device and the mounting terminal is improved while reviewing the configuration of the photoelectric conversion device and the mounting terminal while achieving simplification of the manufacturing process. The present invention relates to an X-ray imaging device and a method for manufacturing a photoelectric conversion device.

Conventionally, an image sensor (photoelectric conversion device) that reads an image by detecting light incident on a photodiode has been proposed. In the light incident area of the image sensor, a plurality of pixel areas partitioned in a matrix are provided. In each of the plurality of pixel regions, a photodiode and a thin film transistor (hereinafter referred to as “TFT”) are provided.

The first electrode of the photodiode is conductively connected to the source region of the TFT, and the second electrode of the photodiode is a common electrode common to the plurality of pixel regions. Since these common electrodes are respectively formed on the uppermost part of the photodiode, they are electrically connected to each other by conductive wiring (hereinafter referred to as “bias line”) formed on the common electrodes. Yes. The drain regions of the plurality of TFTs arranged in the row direction are collectively connected to the data line, and the gate electrodes of the plurality of TFTs arranged in the column direction are collectively connected to the scanning line.

In such a photoelectric conversion device, when light enters the photodiode, a charge is generated in the photodiode. When a voltage is applied to the scanning line by the scanning line driving circuit, the TFT is turned on, and the charge (electric signal) generated in the photodiode is read to the data line.
The read electrical signal is output to the data line readout circuit. Therefore, an image can be read by sequentially reading out charges from a plurality of pixel regions.

In recent years, an attempt has been made to apply a photoelectric conversion device to an X-ray imaging device. One of the X-ray imaging devices is a combination of an image sensor and a scintillator that emits fluorescence upon receiving X-rays. Such an X-ray imaging apparatus is considered to be applied to medical equipment, for example. The X-ray imaging apparatus has an advantage that a fluoroscopic image can be obtained in real time as compared with a still image imaging apparatus using an X-ray film or the like. Further, there is an advantage that a high-resolution fluoroscopic image can be obtained as compared with an imaging device (image intensifier) combined with a photomultiplier tube or a CCD element.

In such a photoelectric conversion device, as shown in the following Patent Documents 1 and 2 as a bias line for electrically connecting the common electrodes formed on the surface of the photodiode, the conductivity is excellent. New metal materials are used. In addition, the bias line is electrically connected to the external connection terminal provided in the peripheral portion of the plurality of pixel regions together with the scanning line and the data line.
An IC chip including an external drive circuit such as a scanning line drive circuit and a flexible printed circuit (FPC) substrate connected to the external drive circuit are mounted on the external connection terminal. .

Such a photoelectric conversion device mounting structure is required to have improved reliability. Therefore, in the invention disclosed in Patent Document 1 below, a tapered contact hole that penetrates both the protective film for protecting the TFT and the protective film for protecting the photodiode is formed, and scanning is performed at the bottom of the contact hole. By exposing the wiring such as lines and data lines and forming a conductive film in contact with the wiring on the wall surface of the contact hole, the wiring is drawn to the surface. In the invention disclosed in Patent Document 2 below, a layer containing an Al alloy containing Ni that has low resistance, good heat resistance, and excellent contact characteristics with other conductive films is used as the bias line. .

JP-A-10-206229 JP 2008-251609 A

According to the inventions disclosed in Patent Documents 1 and 2, the purpose of improving the reliability of the external connection terminals can be achieved. However, in the inventions disclosed in Patent Documents 1 and 2, the metal wiring used as the bias line formed on the surface of the photodiode is extended to the external connection terminal. Metal material is ITO (Indium Tin Oxi
Since the corrosion resistance is lower than that of a transparent conductive metal oxide such as de), there is a problem that corrosion tends to occur when the external connection terminal is formed of a metal material. Therefore, in the mounting structure of the photoelectric conversion device, for the purpose of improving the reliability, it is desired that the uppermost portion of the connection terminal is made of a conductive metal oxide having good corrosion resistance such as ITO.

In addition, as in the inventions disclosed in Patent Documents 1 and 2, when the uppermost bias line of the photodiode is formed of a metal material, the bias line is covered with an insulating film in order to provide corrosion resistance. . Therefore, in order to make the uppermost part of the external connection terminal a transparent conductive metal oxide such as ITO, a bias line made of a metal material is formed on the common electrode of the photodiode, and then an insulating film is formed on the surface thereof. Furthermore, after forming a contact hole in this insulating film, IT
It is necessary to form a transparent conductive metal oxide film such as O. Therefore, the manufacturing process becomes complicated.

In addition, it is necessary to reduce the thickness of the bias line in order to improve the aperture ratio of the photodiode. In order to obtain a high-resolution photoelectric conversion device, it is necessary to reduce the size of each pixel region, and accordingly, it is necessary to further reduce the thickness of the bias line. Therefore, it is difficult to form a bias line particularly in a high-resolution photoelectric conversion device.

The present invention has been made in view of the above circumstances, and in particular, by forming the bias line with a transparent conductive metal oxide such as ITO, it is possible to improve the connection reliability of the external connection terminal and to simplify the operation. It is an object of the present invention to provide a photoelectric conversion device, an X-ray imaging device, and a method for manufacturing a photoelectric conversion device that can be manufactured through various processes.

In order to achieve the above object, in the photoelectric conversion device of the present invention, photodiodes and TFTs are arranged in a matrix in the light detection region, and a plurality of external connection terminals are formed in the periphery of the light detection region. The first electrode is electrically connected to the source region of the TFT, the second electrode is electrically connected to the bias line, and the bias line is electrically connected to the external connection terminal for the bias line. In the photoelectric conversion device, the bias line is formed of a transparent conductive metal oxide, is formed over the entire light incident surface of the light detection region, and is connected to the external connection terminal for the bias line. And is arranged at the top of the external connection terminal for the bias line.

In the photoelectric conversion device of the present invention, the bias line connected to the photodiode is formed of a transparent conductive metal oxide in the light detection region, and the bias line is formed on the entire light incident surface of the light detection region. It is formed over. Since the bias line used in the conventional photoelectric conversion device is made of a light-impermeable metal material, it is necessary to make the bias line thinner in order to improve the aperture ratio of the photodiode. In addition, in order to improve the electrical characteristics of the photoelectric conversion device, it is necessary to reduce the resistance value of the bias line. Therefore, in the conventional photoelectric conversion device, the bias line has to be formed thick.

On the other hand, in the photoelectric conversion device of the present invention, since the bias line is formed of a transparent conductive metal oxide, even if the bias line is formed over the entire light incident surface of the light detection region, the photodiode No effect on the aperture ratio. In addition, according to the photoelectric conversion device of the present invention, the resistance value of the bias line can be easily reduced, so that the characteristics as the photoelectric conversion device are good. As the transparent conductive metal oxide for forming the bias line, the well-known I
It can be appropriately selected from TO, IZO (Indium Zinc Oxide) and the like.

In addition, the electrode of the photodiode to which the bias line is connected is made of a transparent conductive metal oxide because incident light needs to enter the photoelectric conversion portion of the photodiode, for example, the PIN diode portion. In the photoelectric conversion device of the present invention, the electrode to which the bias line of the photodiode is connected and the bias line can be formed of the same material. Therefore, according to the photoelectric conversion device of the present invention, the contact resistance between the photodiode and the bias line is small,
In addition, a photoelectric conversion device with high connection reliability between the photodiode and the bias line can be obtained.

In addition, in the photoelectric conversion device of the present invention, the bias line made of the transparent conductive metal oxide extends to the external connection terminal for the bias line and is arranged at the top of the external connection terminal for the bias line. . Moreover, since transparent conductive metal oxides have better corrosion resistance than metal materials,
It is not necessary to cover the surface of the transparent conductive metal oxide with an insulating film. Therefore, according to the photoelectric conversion device of the present invention, compared with the photoelectric conversion device of the conventional example, it is not necessary to cover the surface of the bias line with an insulating film, so that the configuration is simplified, and an external connection for the bias line is separately provided. A complicated process for making the uppermost portion of the terminal into a conductive metal oxide becomes unnecessary. The external connection terminal in the present invention is used to include both a terminal for connecting to various driving ICs and a terminal for connecting to an FPC board or the like.

In the photoelectric conversion device of the present invention, the bias line has a wiring portion formed between the light incident surface side of the light detection region and the external connection terminal for the bias line,
The routing wiring portion has a multilayer structure with the first routing wiring formed of the same material as that of the first electrode of the photodiode, and is provided at at least one position on each of the light detection region side and the external connection terminal side for the bias line. The first lead wiring is preferably electrically connected to each other.

If the bias line is formed over the entire light incident surface side of the light detection region, the resistance can be reduced in this portion. However, if a bias line routing wiring portion is formed between the light incident surface side of the light detection region and the external connection terminal for the bias line, the resistance value increases because the routing wiring portion needs to be thinned. . Accordingly, in the photoelectric conversion device of the present invention, the bias wiring routing portion is a first material formed of the same material as the first electrode of the photodiode.
The lead wiring has a multilayer structure and is electrically connected to each other in at least one place on the light incident surface side and the bias line external connection terminal side in the light detection region.

With such a configuration, the bias line becomes a parallel circuit of the lead wiring portion of the bias line and the first lead wiring between the light incident surface side of the light detection region and the external connection terminal for the bias line. The resistance can be further reduced. Therefore, the photoelectric conversion device of the present invention has better electrical characteristics. Note that it is preferable to electrically connect the bias line and the first routing wiring through a plurality of vias in order to improve reliability.

In the photoelectric conversion device of the present invention, the first lead wiring has a multilayer structure with the second lead wiring formed of the same material as at least one of the gate electrode and the drain electrode of the TFT, and the light detection region It is preferable that at least one place on each of the light incident surface side and the bias line external connection terminal side is electrically connected to each other.

With such a configuration, the bias line between the light incident surface side of the light detection region and the external connection terminal side for the bias line has a lead wiring portion, a first lead wiring, and a second lead wire.
Since it becomes a parallel circuit of the routing wiring, the resistance can be further reduced, and the electrical characteristics of the photoelectric conversion device are improved. The electrical connection between the first routing wiring and the second routing wiring is also preferably electrically connected through a plurality of vias in order to improve reliability.

In the photoelectric conversion device of the present invention, the gate electrode and the drain electrode of the thin film transistor are electrically connected to the scanning line and the data line, respectively, and the external connection terminal is respectively connected to the scanning line and the data line. It has scanning line or data line external connection terminals that are electrically connected, and the uppermost portions of the scanning line and data line external connection terminals are made of the same material as the bias line. Is preferred.

According to the photoelectric conversion device of the present invention, the uppermost portion of the scanning line or data line external connection terminal is formed of the same conductive metal oxide as the bias line. Therefore, the uppermost portion of the scanning line or data line external connection terminal can be formed by the same manufacturing process as the manufacturing process of the bias line connection terminal, which simplifies the configuration and facilitates manufacturing.

Furthermore, in order to achieve the said objective, the manufacturing method of the photoelectric conversion apparatus of this invention is the following.
Forming a matrix in a state where the first electrode of the photodiode is connected to the source region of the TFT and the second electrode is exposed;
Coating the surface of the photodiode with an insulating film;
Forming a contact hole in the insulating film such that the second electrode of the photodiode is exposed;
Forming a thin film made of a transparent conductive metal oxide so as to cover the surface of the insulating film and the surface of the second electrode;
Patterning the transparent conductive metal oxide to form a bias line and an external connection terminal for the bias line;
It is characterized by providing.

According to the method for manufacturing a photoelectric conversion device of the present invention, it is possible to easily manufacture the photoelectric conversion device of the present invention that exhibits the above effects.

Furthermore, in order to achieve the above object, the X-ray imaging apparatus of the present invention includes a light conversion unit that converts incident X-rays into light having a longer wavelength than the X-rays and emits the light toward the photoelectric conversion device; It is characterized by having.

Since the configuration of the photoelectric conversion device of the present invention is simpler than that of the conventional photoelectric conversion device, the configuration of the X-ray imaging device of the present invention is also simpler than that of the conventional X-ray imaging device.

It is a perspective view which shows schematic structure of an X-ray imaging device. It is a schematic diagram which shows the circuit structure of a photoelectric conversion apparatus. It is a schematic plan view of a photoelectric conversion apparatus. It is a top view which shows the structure of the pixel area | region of a photoelectric conversion apparatus. It is sectional drawing which follows the VV line of FIG. It is sectional drawing which follows the VI-VI line of FIG. 7A is a plan view of the scanning line external connection terminal, and FIG. 7B is a cross-sectional view taken along the line VIIB-VII in FIG. 7A. FIG. 8A is a cross-sectional view of the data line external connection terminal, and FIG. 8B is a cross-sectional view of a modification of the scan line external connection terminal. 9A to 9E are process diagrams schematically showing a method for manufacturing a photoelectric conversion device. 10A to 10D are process diagrams continuing from FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that in the drawings used for explanation, in order to show characteristic portions in an easy-to-understand manner, dimensions and scales of structures in the drawings may be different from actual structures. In addition, regarding the similar components in the embodiment,
The same reference numerals are used for illustration, and detailed description thereof may be omitted.

FIG. 1 is a perspective view showing a schematic configuration of an X-ray imaging apparatus 1 according to the present embodiment. FIG.
As shown in FIG. 1, the X-ray imaging apparatus 1 includes a photoelectric conversion device 2 and a scintillator (light conversion unit) 3.
Is included. The photoelectric conversion device 2 is an application of the photoelectric conversion device of the present invention.

The photoelectric conversion device 2 has a substantially rectangular light detection region A1. The light detection area A1 is partitioned into a plurality of pixel areas A2 having a substantially rectangular shape. The plurality of pixel regions A2 are arranged in a matrix. A photoelectric conversion element to be described later is disposed in each of the plurality of pixel regions A2. A plurality of first external connection terminals 211 are provided in a peripheral portion (frame) along one side of the light detection region A1. The first external connection terminal 211 is connected to the scanning line driving circuit (external driving circuit) 21. A plurality of second external connection terminals 221 are provided in the peripheral portion along the other side of the light detection region A1.
The second external connection terminal 221 is connected to the data line readout circuit (external drive circuit) 22.

The X-ray imaging apparatus 1 according to the present embodiment generally operates as follows. For example,
The X-ray imaging apparatus 1 is a medical device, and the imaging target 9 is a person. The X-ray L1 emitted from the emission source 8 of the X-ray L1 enters the imaging target 9. A part of the X-ray L1 incident on the imaging object 9 is scattered and absorbed by the imaging object 9.

As a result, the intensity distribution of the X-ray L2 that has passed through the imaging object 9 is a distribution that reflects the internal composition and internal structure of the imaging object 9. The X-ray L2 that has passed through the imaging object 9 enters the scintillator 3. The scintillator 3 is made of a film made of cesium iodide (CsI) or the like, and is disposed in contact with the light detection region A1 side of the photoelectric conversion device 2. The scintillator 3 converts the incident X-ray L2 into fluorescence L3 having a wavelength longer than that of the X-ray L2 and emits the converted X-ray. The intensity distribution of the emitted fluorescence L3 is a distribution reflecting the intensity distribution of the X-ray L2 incident on the scintillator 3.

The fluorescence L3 emitted from the scintillator 3 is spatially divided and incident on the plurality of pixel regions A2 of the photoelectric conversion device 2. The light incident on the pixel area A2 generates charges in the photoelectric conversion elements arranged in the pixel area A2. This electric charge is read for each pixel area A2 by the reading circuit, and becomes data indicating a fluoroscopic image of the imaging object 9.

Hereinafter, the configuration of the photoelectric conversion device 2 will be described with reference to FIGS. FIG. 2 shows a photoelectric conversion device 2
It is a schematic diagram which shows the structure of the read-out circuit. FIG. 3 is a schematic plan view of the photoelectric conversion device 2. FIG.
FIG. 3 is an enlarged plan view showing a planar configuration of a pixel region A2. FIG. 5 is a cross-sectional view taken along line VV in FIG. In FIGS. 3 and 4, some components of the photoelectric conversion device 2 are omitted for easy understanding of the drawings.

As shown in FIG. 2, the scanning line driving circuit 21 includes a plurality of scanning lines 212 extending in parallel with each other.
The plurality of scanning lines 212 are connected to the first external connection terminal 211 for each scanning line 212. The plurality of scanning lines 212 are electrically connected to the scanning line driving circuit 21 via the first external connection terminal 211.

A plurality of data lines 222 are extended along a direction substantially orthogonal to the scanning lines 212. The plurality of data lines 222 are electrically connected to the second external connection terminal 221 for each data line 222. The plurality of data lines 222 are electrically connected to the data line read circuit 22 via the second external connection terminal 221.

Each of the scanning line driving circuit 21 and the data line reading circuit 22 includes a shift register, a level shifter, a video line, an analog switch, and the like. The scanning line driving circuit 21 and the data line reading circuit 22 are actually formed in an IC chip (not shown) or the like. IC
The chip is mounted with the first external connection terminal 211 and the second external connection terminal 221 as external connection terminals. In some cases, an FPC connected to an external drive circuit such as the scanning line drive circuit 21 or the data line readout circuit 22 is mounted on an external connection terminal.

Each of the areas partitioned by the scanning lines 212 and the data lines 222 is a pixel area A2. In the photoelectric conversion device 2 of the present embodiment, ITO or I extends over the entire light detection region A1.
It is covered with a transparent conductive metal oxide made of ZO. That is, the surface of all the pixel regions A2 is covered with the transparent conductive metal oxide. This transparent conductive metal oxide acts as a bias line 23. The bias line 23 has an end A3 of the light detection region A1,
It extends to the external connection terminal 231 for the bias line through the routing wiring portion A4 for the bias line.

A photodiode (photoelectric conversion element) 25 is disposed in each of the plurality of pixel regions A2. In the pixel area A2, there is a TF near the area where the scanning line 212 intersects the data line 222.
T24 is arranged.

The gate electrode 241 of the TFT 24 is formed integrally with the scanning line 212. Scan line 212
In FIG. 8, the portion formed to protrude to the pixel region A 2 is a gate electrode 241.
The drain region 242 of the TFT 24 is conductively connected to a portion formed in the data line 222 so as to protrude from the pixel region A2. The source region 243 of the TFT 24 is electrically connected to the conductive portion 281.

The first electrode 251 of the photodiode 25 is electrically connected to the conductive portion 281 in the contact hole H1. The second electrode 252 of the photodiode 25 is electrically connected to the bias line 23.

The second electrode 252 of the present embodiment is provided independently for each pixel region A2. A bias line 23 made of a transparent conductive metal oxide is formed on the entire surface of the light detection region A1. Therefore, the second electrodes 252 of the plurality of photodiodes 25 are collectively connected to the bias line 23.

The scanning line 212 and the data line 222 are provided between the pixel regions A <b> 2 and the second electrode 252.
Does not overlap the scanning line 212 or the data line 222 in a planar manner. Accordingly, the capacitance between the second electrode 252 and the scanning line 212 and the capacitance between the second electrode 252 and the data line 222 are reduced.

When the fluorescence L3 is incident on the photodiode 25, an electric charge is generated in the photoelectric conversion layer of the photodiode 25. When a scanning signal is supplied from the scanning line driving circuit 21 to the scanning line 212, the plurality of TFTs 24 connected to the scanning line 212 are turned on. When the TFT 24 is turned on, the electric charge generated in the photodiode 25 flows to the data line 222 through the channel region of the TFT 24, and this current is read to the data line reading circuit 22 as an electric signal.

In this way, electrical signals are read out in parallel from the plurality of TFTs 24 connected to one scanning line 212. After the electrical signal is read from the TFT 24 corresponding to one scanning line 212, the plurality of data lines 222 are discharged and held at a predetermined potential. After the plurality of data lines 222 reach a predetermined potential, the scanning signal is supplied from the scanning line driving circuit 21 to the next scanning line 212.

Similarly, electrical signals corresponding to each of the charges generated in the plurality of photodiodes 25 are sequentially read out. As described above, since the capacitance between the scanning line 212 or the data line 222 and the second electrode 252 is reduced, noise due to the capacitance may be generated in an electric signal passing through the scanning line 212 or the data line 222. Reduced.

FIG. 5 is a cross-sectional view taken along the line VV in FIG. As shown in FIG. 5, the photoelectric conversion device 2
Is formed using, for example, a substrate 20 made of glass or the like as a base. Substrate 20 is scanning line 2
12 (see FIG. 4) is a wiring base layer. A TFT 24 is provided on the substrate 20. The TFT 24 includes a gate electrode 241, a drain region 242, a source region 243,
A gate insulating film 244 and a semiconductor layer 245 are included.

The gate electrode 241 is made of a wiring material selected as appropriate, for example, a simple substance or an alloy of a metal material such as aluminum, molybdenum, titanium, silver, tantalum, chromium, or tungsten. The gate electrode 241 of this embodiment is made of aluminum / molybdenum. The gate insulating film 244 is provided on almost the entire surface of the substrate 20 so as to cover the gate electrode 241. Gate insulation film 2
44 is made of an insulating material such as silicon nitride or silicon oxide. The gate insulating film 244 is a wiring base layer for the data line 222. The gate insulating film 244 of this embodiment is made of silicon nitride or the like and has a thickness of about 200 to 500 nm.

The semiconductor layer 245 is made of, for example, polysilicon or amorphous silicon. The drain region 242 and the source region 243 are provided on the semiconductor layer 245 at positions separated from each other. The drain region 242 and the source region 243 are made of amorphous silicon into which impurities are implanted at a high concentration, for example. In the semiconductor layer 245, a region between the drain region 242 and the source region 243 functions as a channel region.

A data line 222 is provided in contact with the drain region 242. Source region 243
The conductive portion 281 is provided continuously from the source region 243 to the gate insulating film 244. The source region 243 corresponds to the TFT driving electrode in the present invention.
The data line 222 and the conductive portion 281 are made of a wiring material such as aluminum or molybdenum.

A first passivation film 291 that covers the data line 222, the conductive portion 281, the gate insulating film 244 and the like and protects the TFT 24 is provided. The first passivation film 291 is
It is provided over almost the entire surface of the substrate 20. The first passivation film 291 is an intermediate layer with respect to the scanning lines 212 and the data lines 222. The first passivation film 291 is made of, for example, silicon nitride and has a thickness of about 200 nm to 500 nm.

The first passivation film 291 is provided with a contact hole H1 leading to the conductive portion 281. A first electrode 251 is provided continuously in the contact hole H1 and on the first passivation film 291. The first electrode 251 is in contact with the conductive portion 281 in the contact hole H1.

An n-type semiconductor layer 253, an i-type semiconductor layer 254, and a p-type semiconductor layer 255 are arranged in this order from the first electrode 251 side on the first electrode 251 drawn out on the first passivation film 291. Yes. The semiconductor layers 253 to 255 constitute a photoelectric conversion layer. A second electrode 252 is formed on the photoelectric conversion layer. The second electrode 252 is on the light incident side, and is made of, for example, a transparent conductive metal oxide such as ITO.

A second passivation film 292 is provided to cover the pixel region A2 (see FIG. 4) excluding the central portion of the second electrode 252. Here, the second passivation film 292 is provided on almost the entire surface of the substrate 20. The second passivation film 292 is made of, for example, silicon nitride and has a thickness of about 200 to 500 nm.

A planarizing film 293 is provided so as to cover almost the entire surface of the substrate 20 excluding the central portion of the photodiode 25 and the external connection terminal formation region. The planarizing film 293 is a wiring base layer with respect to the bias line 23. The planarization film 293 is made of a resin material such as polyimide resin or acrylic resin, and has a thickness of about 1 to 5 μm.

A bias line 23 is formed in contact with the central portion of the second electrode 252 exposed between the planarization films 293. The bias line 23 is made of a transparent conductive metal oxide and has a light detection region A1 (
(See FIG. 3). The bias line 23 is a surface layer of the element layer.

Next, the structure of the external connection terminal 231 for the bias line will be described with reference to FIG. 6 is a cross-sectional view taken along line VI-VI in FIG.

As shown in FIG. 6, the external connection terminal 231 for the bias line includes a first connection conductive part 232 and a second connection conductive part 233. The first connection conductive portion 232 is a data line 222 (see FIG. 5).
Are formed on the same layer (on the gate insulating film 244) and are made of the same material as the data line 222. The first connection conductive portion 232 is provided at a position overlapping the external connection terminal 231 for the bias line in a plan view from the end A3 of the light detection region A1 through the routing wiring portion A4 for the bias line.

The second connection conductive portion 233 is provided on the same layer as the first electrode 251 (see FIG. 5) (on the first passivation film 291), and is made of the same material as the first electrode 251.
The second connection conductive portion 233 is provided at a position where it planarly overlaps with a part of the external connection terminal 231 for the bias line from the end A3 of the light detection region A1 through the routing wiring portion A4 for the bias line. Yes.

On the side of the external connection terminal 231 for the bias line, the contact hole H penetrates the first passivation film 291 in a portion where the second connection conductive portion 233 overlaps the first connection conductive portion 232.
2 is provided. A part of the second connection conductive portion 233 is buried in the contact hole H2 and constitutes a via. Second connection conductive portion 2 on the first passivation film 291
33 is conductively connected to the first connection conductive portion 232 through this via.

In addition, the second connection conductive portion 233 is connected to the first connection conductive portion 2 at the end A3 of the light detection region A1.
A contact hole H 4 is provided through the first passivation film 291 in a portion overlapping with 32. A part of the second connection conductive portion 233 is buried in the contact hole H4 and forms a via. Second connection conductive portion 233 on the first passivation film 291
Is electrically connected to the first connection conductive portion 232 through this via.

Further, on the side of the external connection terminal 231 for the bias line, the second on the second connection conductive portion 233.
A contact hole H3 is provided in the passivation film 292. Photodetection area A1
In the end portion A3, a contact hole H5 is provided in the second passivation film 292 on the second connection conductive portion 233.

The bias line 23 is formed in the contact holes H3 and H5 and the second passivation film 29.
2 and the planarizing film 293 are continuously formed. A part of the bias line 23 is embedded in the contact holes H3 and H5 to form a via. The bias line 23 is conductively connected to the second connection conductive portion 233 through this via.

Note that the contact holes H2 to H5 of the present embodiment are all formed by dry etching. The inner diameters of the contact holes H2 to H5 gradually increase in the direction from the substrate 20 toward the surface layer. That is, the contact holes H2 to H5 are tapered with a small diameter on the substrate 20 side.

In this embodiment, two contact holes H2 to H5 are formed, and two corresponding vias are formed. This improves the reliability of the electrical connection through each via. Each contact hole H2 to H5 may be formed at one place or three places or more as needed.

In this way, the first connection conductive portion 232 and the second connection conductive portion 233 are connected in parallel from the end A3 of the light detection region A1 to the external connection terminal 231 side for the bias line. Further, the bias line 23 is connected in parallel with the first connection conductive part 232 and the second connection conductive part 233 from the end A3 of the light detection region A1 to the external connection terminal 231 side for the bias line. As a result, the resistance value between the end A3 of the light detection region A1 of the bias line 23 and the external connection terminal 231 for the bias line is very low even if the width of the lead wiring portion A4 for the bias line is narrow. Become.

The external connection terminal 231 for the bias line of this embodiment is made of ITO and can withstand corrosion and oxidation. For the external connection terminal 231 for the bias line, by a known mounting technique, for example, ACF connection using an anisotropic conductive film, connection using a bump electrode, etc.
An IC chip (not shown) including the scanning line driving circuit 21 is mounted.

Next, the structure of the first external connection terminal 211 and the second external connection terminal 221 will be described with reference to FIGS. 7A is a plan view of the first terminal portion including the first external connection terminal 211, and FIG. 7B is a cross-sectional view taken along the line VIIB-VIIB in FIG. 7A. 8A is a cross-sectional view corresponding to FIG. 7B including the second external connection terminal 221, and FIG. 8B is a cross-sectional view corresponding to FIG. 7B of a modification including the first external connection terminal 211. In FIG. 7A, in order to make the drawing easier to see,
Illustration of an insulating film such as a passivation film is omitted. 8A and 8B omit the plan view.

As shown in FIGS. 7A and 7B, the first terminal portion includes an end portion of the scanning line 212, a third connection conductive portion 282, a fourth connection conductive portion 283, and a first external connection terminal 211. The third connection conductive portion 282 is provided on the same layer (on the gate insulating film 244) as the data line 222 (see FIG. 5) and is made of the same material as the data line 222. The third connection conductive portion 282 is
A part of the scanning line 212 is provided at a position overlapping the end of the scanning line 212 in a plan view.

A contact hole H6 is provided through the gate insulating film 244 in a portion where the third connection conductive portion 282 overlaps the scanning line 212. A part of the third connection conductive portion 282 is buried in the contact hole H6 and forms a via. The third connection conductive portion 282 on the gate insulating film 244 is conductively connected to the scanning line 212 through this via.

The fourth connection conductive portion 283 is provided on the same layer as the first electrode 251 (see FIG. 5) (on the first passivation film 291), and is made of the same material as the first electrode 251.
The fourth connection conductive part 283 is provided at a position where a part thereof overlaps with a part of the third connection conductive part 282 in plan view. In the portion where the fourth connection conductive portion 283 overlaps the third connection conductive portion 282,
A contact hole H7 is provided through the passivation film 291. A part of the fourth connection conductive portion 283 is embedded in the contact hole H7 to form a via. The fourth connection conductive portion 283 on the first passivation film 291 is connected to the third connection via this via.
The connection conductive portion 282 is electrically connected.

The first external connection terminal 211 is provided on the same layer (second passivation 292) as the bias line 23 (see FIG. 5) and is made of the same material as the bias line 23. The fourth connection conductive portion 283 is covered with the second passivation film 292. A contact hole H8 is provided in the second passivation film 292 on the fourth connection conductive portion 283. The first external connection terminal 211 is continuously formed in the contact hole H8, over the second passivation film 292, and over the planarization film 293.

A part of the first external connection terminal 211 is embedded in the contact hole H8 to form a via. The first external connection terminal 211 on the second passivation 292 is conductively connected to the fourth connection conductive portion 283 through this via. In this embodiment, the contact holes H6 to H8 are formed one by one, and the corresponding vias are formed one by one. However, in order to improve the reliability of the electrical connection through each via, each contact hole H6 to H8 may be formed at two or more locations.

Note that the contact holes H6 to H8 of this embodiment are all formed by dry etching. The inner diameters of the contact holes H6 to H8 are gradually enlarged in the direction from the substrate 20 toward the surface layer. That is, the contact holes H6 to H8 are tapered with a small diameter on the substrate 20 side.

The first external connection terminal 211 of the present embodiment is made of ITO and can withstand corrosion and oxidation. The first external connection terminal 211 is connected to the scanning line driving circuit 21 (by an ACF connection using an anisotropic conductive film, a connection using a bump electrode, or the like by a known mounting technique.
An IC chip (not shown) including a chip is mounted.

Further, as shown in FIG. 8A, the second terminal portion includes the end portion of the data line 222 and the fifth connection conductive portion 2.
84, the second external connection terminal 221 is included. The second terminal portion has an upper layer structure substantially the same as that of the first terminal portion than the gate insulating film 244. That is, the fifth connection conductive portion 284 is
Similar to the fourth connection conductive portion 283, the first electrode 251 and the same layer are formed of the same forming material. The fifth connection conductive portion 284 is provided at a position where a part thereof overlaps the end portion of the data line 222 in a plan view. A contact hole H9 is provided through the first passivation film 291 at a portion where the fifth connection conductive portion 284 overlaps the data line 222. A part of the fifth connection conductive portion 284 is embedded in the contact hole H9 to form a via. The fifth connection conductive portion 284 is conductively connected to the end of the data line 222 through this via.

The second external connection terminal 221 is formed of the same material as the bias line 23 on the same layer as the external connection terminal 231 for bias line (see FIG. 6). Fifth connection conductive portion 284
Is covered with a second passivation film 292. A contact hole H10 is provided in the second passivation film 292 on the fifth connection conductive portion 284.

The second external connection terminals 221 are provided in the contact hole H10 and the second passivation film 2.
It is continuously formed over 92. A part of the second external connection terminal 221 is embedded in the contact hole H10 to form a via. The second external connection terminal 221 is conductively connected to the fifth connection conductive portion 284 through this via.

The contact holes H9 and H10 are similar to the contact holes H2 to H5 in the substrate 20
The side is tapered with a small diameter. In this embodiment, the contact holes H9 and H10 are formed one by one and the corresponding vias are formed one by one. However, in order to improve the reliability of electrical connection through each via, each contact hole H9 and H10 may be formed at two or more locations.

The second external connection terminal 221 of this embodiment is made of ITO and can withstand corrosion and oxidation. An IC chip (not shown) including the data line readout circuit 22 is mounted on the second external connection terminal 221.

In the photoelectric conversion device 2 configured as described above, the scanning line 212 is connected to the third connection conductive portion 28.
The second external connection terminal 211 is conductively connected via the second and fourth connection conductive portions 283. Between the scanning line 212 and the third connection conductive portion 282, the third connection conductive portion 282 and the fourth connection conductive portion 28.
3, and the fourth connection conductive portion 283 and the first external connection terminal 211 are all conductively connected by vias.

When the configuration of this embodiment is compared with, for example, a configuration in which the scanning line is conductively connected to the first external connection terminal by one via, a step (via height) per via is
The configuration of this embodiment is much smaller. Therefore, the coverage of the via forming material at the step is improved, and the occurrence of step breakage in the via is significantly reduced. Therefore, the connection reliability between the scanning line 212 and the first external connection terminal 211 is remarkably increased, and the highly reliable photoelectric conversion device 2 is obtained.

Since the data line 222 is conductively connected to the second external connection terminal 221 via the fifth connection conductive portion 284, the data line 222 and the second external connection terminal 221 are connected for the same reason as the scanning line 212. And the reliability of the photoelectric conversion device 2 becomes extremely high.

Further, since the contact holes H6 to H10 are tapered, the coverage of the via forming material is improved in the contact holes H6 to H10, and the occurrence of disconnection in the vias is further reduced. Further, in the configuration of the present embodiment, since the via height is reduced, the diameter of the contact holes H6 to H10 on the surface layer side can be reduced, and the first external connection terminal 211 and the second external connection terminal 221 are narrowed. Can be pitch. Thereby, it becomes easy to make the scanning lines 212 and the data lines 222 narrow in pitch, and it becomes easy to make the photoelectric conversion device 2 have a high resolution.

In addition, the second electrode 252 of the photodiode 25 is independent for each pixel region A2,
It is not provided between the pixel regions A2. Accordingly, since the second electrode 252 and the data line 222 do not overlap, capacitive coupling between the second electrode 252 and the data line 222 is reduced.
The plurality of second electrodes 252 are collectively connected to the bias line 23 and substantially function as a common electrode, so that the drive system is prevented from becoming complicated.

The bias line 23 is formed in a solid shape and intersects with the data line 222, but the planarizing film 2
As a result, the capacitive coupling is reduced. As described above, since the capacitive coupling of the data line 222 is remarkably reduced, the occurrence of noise or the like in the data read via the data line 222 is remarkably reduced. Therefore, in the photoelectric conversion device 2 of this embodiment, the charges generated in the photodiode 25 can be accurately read, and a high-resolution image can be obtained.

In the photoelectric conversion device 2 of the present embodiment, the bias line 23 is formed of a transparent conductive metal oxide such as ITO. Since transparent conductive metal oxides such as ITO have better corrosion resistance than metal materials, they do not have to be covered with a separate passivation film. As a result, the photoelectric conversion device 2 according to the present embodiment is simpler in configuration than the case where the bias line 23 is formed of a metal material, the aperture ratio is improved, and the number of manufacturing steps can be reduced. Become.

The technical scope of the present invention is not limited to the above embodiment. The present invention can be variously modified without departing from the gist of the present invention. For example, a storage capacitor that holds charges generated in the photodiode 25, an amplifying TFT that amplifies current, and the like may be provided.

In this embodiment, the insulating film (the gate insulating film or the first and second films) formed on the substrate 20 is also used.
Although an example in which an independent contact hole is formed for each passivation film) is shown, a contact hole penetrating through two or more insulating films may be used. Hereinafter, modified examples of such a configuration will be described.

FIG. 8B is a cross-sectional view corresponding to FIG. 7B of the first terminal portion of the modified example including the first external connection terminal 211. As shown in FIG. 8B, the first terminal portion of the modification includes the end portion of the scanning line 212, the sixth connection conductive portion 285, and the first external connection terminal 211. The first terminal portion of the modified example is different from the above embodiment in that the third connection conductive portion 282 is not provided in contact with the gate insulating film 244.

In the modification, a contact hole H <b> 11 is formed on the end portion of the scanning line 212 so as to penetrate the first passivation film 291 and the gate insulating film 244. Contact hole H11
A sixth connection conductive portion 285 is provided over the inside and on the first passivation film 291. The sixth connection conductive portion 285 is formed together with the first electrode 251 (see FIG. 5) and is made of the same material as that of the first electrode 251. Regarding the structure above the sixth connection conductive portion 285, the first external connection terminal 211 is electrically connected to the sixth connection conductive portion 285 via the contact hole H12 formed in the second passivation film 292. It is the same as that of the said embodiment except being.

Even when it is a contact hole that penetrates two or more insulating films as in the modification,
If a connection conductive part is provided in one or more of the insulating films, and the connection conductive part is relayed and the wiring and the external connection terminal are conductively connected, an effect of improving the connection reliability can be obtained. Depending on the total thickness of the insulating film in which one of the contact holes is provided, a contact hole is provided for each insulating film, or 2
What is necessary is just to select whether the contact hole which penetrates the above insulating films is provided.

For example, if the total thickness of the plurality of insulating films is a thickness that does not impair the coverage of the via forming material, the contact holes may be formed in the plurality of insulating films at once. When forming contact holes in a plurality of insulating films at a time, if the plurality of insulating films are formed of the same material as in the embodiment, the etching conditions for etching the plurality of insulating films are as follows. It becomes easy to adjust.

Next, a method for manufacturing a photoelectric conversion device according to the present invention will be described based on the photoelectric conversion device 2 with reference to FIGS. 9A to 9E and FIGS. 10A to 10D show the photoelectric conversion device 2.
It is process drawing which shows the manufacturing method of no.

In these process diagrams, the formation region (pixel region) A2 of the TFT 24 and the photodiode 25 is shown.
The first terminal portion formation region A5, the second terminal portion formation region A6, and the bias line external terminal region A7 are shown in parallel. In each process drawing, the formation area A2 corresponds to the cross section shown in FIG. 5, the formation area A5 is the cross section shown in FIG. 7B, the formation area A6 is the cross section shown in FIG. 8A, and the external terminal area A7 is FIG. Corresponds to the cross section shown in FIG. In each of these process diagrams,
The fine structure is not shown.

In order to manufacture the photoelectric conversion device 2, first, a wiring material (for example, aluminum / molybdenum) is formed on the substrate 20 as shown in FIG. 212 and the gate electrode 241 are formed together.

Next, as shown in FIG. 9B, over the scanning line 212 and the gate electrode 241,
An insulating material (for example, silicon nitride) is formed on almost the entire surface of the substrate 20 to form a gate insulating film 244.
Form. Then, a semiconductor layer 245 made of, for example, amorphous silicon is formed on a portion of the gate insulating film 244 that overlaps the gate electrode 241 in a planar manner. And semiconductor layer 2
A drain region 242 and a source region 243 are formed on the semiconductor layer 245 or on the semiconductor layer 245. Thereby, the TFT 24 is formed. Further, a contact hole H6 is formed in the gate insulating film 244 that overlaps with the end of the scanning line 212.

Next, as shown in FIG. 9C, a conductive material (for example, aluminum / molybdenum) is formed on almost the entire surface of the substrate 20 including the inside of the contact hole H6 and the gate insulating film 244. Then, by patterning this film, the data line 222 and the conductive portion 281 are formed.
The first connection conductive portion 232 and the third connection conductive portion 282 are collectively formed.

Next, as shown in FIG. 9D, an insulating material (for example, silicon nitride) is formed on almost the entire surface of the substrate 20 including the conductive portion 281, the first connection conductive portion 232, the third connection conductive portion 282, and the data line 222. ) To form a first passivation film 291. Then, by patterning the first passivation film 291, the contact holes H 1, H 2, H 4, H
7 and H9 are formed together.

Next, as shown in FIG. 9E, a conductive material (for example, aluminum / molybdenum) is applied to almost the entire surface of the substrate 20 in the contact holes H1, H2, H4, H7, and H9 and on the first passivation film 291. Form a film. Then, the first electrode 251, the second connection conductive portion 233, the fourth connection conductive portion 283, and the fifth connection conductive portion 284 are collectively formed by patterning this film.

Next, as illustrated in FIG. 10A, the n-type semiconductor layer 253, i is formed on the first electrode 251.
A photoelectric conversion layer is formed by sequentially forming a p-type semiconductor layer 254 and a p-type semiconductor layer 255. Then, a second electrode 252 made of a transparent conductive metal oxide such as ITO is formed on the photoelectric conversion layer. Next, the second electrode 252 is patterned, and the p-type semiconductor layer 255, the i-type semiconductor layer 254, and the n-type semiconductor layer 253 are patterned. As a result, the photodiode 2
5 is formed.

Further, as shown in FIG. 10B, an insulating material (for example, silicon nitride) is formed on almost the entire surface of the substrate 20 to form a second passivation film 292. Further, a planarizing film (organic insulating film) 293 is formed by forming a resin material on almost the entire surface of the substrate 20. Then, the planarizing film other than the light detection region A1 (see FIG. 3) and the central portion of the second electrode 252 are removed.

Then, by patterning the second passivation film 292, the second electrode 25 is obtained.
2 is exposed, and contact holes H3, H5, H8, and H10 are collectively formed.

Next, as shown in FIG. 10C, the contact hole H is formed on the center portion of the second electrode 252.
3, H5, H8, H10, over the planarizing film 293 and in the opening, I substantially over the entire surface of the substrate 20
A transparent conductive metal oxide layer 23 ′ such as TO is formed. Then, as shown in FIG. 10 (d), by patterning this transparent conductive metal oxide layer 23 ′, the bias line 23,
Bias line external connection terminal 231, first external connection terminal 211, second external connection terminal 221
Are collectively formed.

As described above, the photoelectric conversion device 2 of the embodiment is obtained. Further, by providing a scintillator 3 corresponding to the light detection region A1 of the photoelectric conversion device 2, the X-ray imaging device 1 is provided.
Is obtained.

In the manufacturing method of the present embodiment, the scanning line 212 and the first external connection terminal 211 and the data line 222 and the second external connection terminal 221 are conductively connected in a plurality of steps. ing. Therefore, the level difference per step is reduced, and the occurrence of disconnection in the vias interposed in the level difference is significantly reduced. Therefore, the connection reliability between the wiring and the external connection terminal is increased, and the photoelectric conversion device 2 can be manufactured with a good yield.

In addition, the data line 222, the first connection conductive portion 232, the conductive portion 281 and the third connection conductive portion 282.
In addition, the first electrode 251, the second connection conductive portion 233, the fourth connection conductive portion 283, and the fifth connection conductive portion 284 are collectively formed, and the bias line 23, A bias line external connection terminal 231, a first external connection terminal 211, and a second external connection terminal 221 are collectively formed.

In this way, the first connection conductive portion 232, the second connection conductive portion 233, the third connection step are formed in common with the process of forming the conductive line pattern such as the data line 222, the conductive portion 281 and the first electrode 251.
Since the sixth connection conductive portions 282 to 285 are formed, an independent process for forming the connection conductive portion can be simplified or omitted, and the photoelectric conversion device can be efficiently manufactured.

In addition, the bias line 23, the external connection terminal 231 for the bias line, the first external connection terminal 21
Since the first and second external connection terminals 221 are collectively formed of a transparent conductive metal oxide layer such as ITO having good corrosion resistance, it is not necessary to separately cover these surfaces with an insulating layer. Can be simplified. In addition, since the bias line 23 made of a transparent conductive metal oxide is formed over the entire light detection region A1, light incident on the photodiode 25 is not blocked, and the aperture ratio increases. A highly sensitive photoelectric conversion device is obtained.

DESCRIPTION OF SYMBOLS 1 ... X-ray imaging device 2 ... Photoelectric conversion device 3 ... Scintillator 23 ... Bias line
25 ... Photodiode (photoelectric conversion element) 211 ... First external connection terminal 212 ... Scanning line 221 ... Second external connection terminal 222 ... Data line 231 ... External connection terminal for bias line 232 ... First connection conductive portion 233 ... First 2 connection conductive portion 24 ... TFT 242 ... drain region 243 ... source region 244 ... gate insulating film 245 ... semiconductor layer 251 ... first electrode 281 ... conductive portion 282 ... third connection conductive portion 283 ... fourth connection conductive portion 284 ... first 5
Connection conductive portion 285 ... Sixth connection conductive portion A1 ... Photodetection region A2 ... Pixel region A3 ... End portion of photodetection region A4 ... Lead wiring portion for bias line A5 ... First external connection terminal region
A6: Second external connection terminal region A7: External connection terminal region for bias line H1 to H12 ...
Contact hole

Claims (6)

Photodiodes and thin film transistors are arranged in a matrix in the light detection region,
A plurality of external connection terminals are formed in the periphery of the light detection region,
The photodiode has a first electrode electrically connected to a source region of the thin film transistor, a second electrode electrically connected to a bias line,
A photoelectric conversion device in which the bias line is electrically connected to an external connection terminal for a bias line,
The bias line is formed of a transparent conductive metal oxide, is formed over the entire light incident surface of the photodetection region, and extends to an external connection terminal for the bias line to extend the bias. A photoelectric conversion device arranged at the top of an external connection terminal for a wire. The bias line has a lead wiring portion formed between the light detection region and the external connection terminal for the bias line, and the lead wiring portion is formed of the same material as the first electrode of the photodiode. One lead-out wiring and a multi-layer structure are characterized in that they are electrically connected to the first lead-out wiring at at least one place on each of the light detection region side and the external connection terminal side for the bias line. The photoelectric conversion device according to claim 1. The first routing wiring has a multilayer structure with the second routing wiring formed of the same material as at least one of the gate electrode and the drain electrode of the thin film transistor, and the external connection terminal for the photodetection region side and the bias line The photoelectric conversion device according to claim 2, wherein the photoelectric conversion devices are electrically connected to each other at at least one location on the side. The gate electrode and the drain electrode of the thin film transistor are electrically connected to the scan line and the data line, respectively,
The external connection terminal includes an external connection terminal for a scan line and a data line electrically connected to the scan line and the data line, respectively, and the uppermost part of the external connection terminal for the scan line or the data line The photoelectric conversion device according to claim 1, wherein the photoelectric conversion device is made of the same material as the bias line. Forming the first electrode of the photodiode in a matrix form in a state where the first electrode of the photodiode is connected to the source region of the thin film transistor and the second electrode is exposed;
Coating the surface of the photodiode with an insulating film;
Forming a contact hole in the insulating film such that the second electrode of the photodiode is exposed;
Forming a thin film made of a transparent conductive metal oxide so as to cover the surface of the insulating film and the surface of the second electrode;
Patterning the transparent conductive metal oxide to form a bias line and an external connection terminal for the bias line;
A process for producing a photoelectric conversion device comprising: The photoelectric conversion device according to any one of claims 1 to 4,
An X-ray imaging apparatus comprising: a light conversion unit that converts incident X-rays into light having a wavelength longer than that of the X-rays and emits the light toward the photoelectric conversion apparatus.

Images