JP2002158340A - Radiation imaging device, photoelectric conversion device, and radiation imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize offset correction and external noise correction without arranging a lead plate on a fluorescent material. SOLUTION: The radiation imaging device comprises a plurality of photoelectric conversion elements, and a scintillator for converting incident radiation into light having a wavelength detectable through the photoelectric conversion element in which light from the scintillator 9 is shielded by extending a conductive layer 6 being connected with a part of the plurality of photoelectric conversion elements to cover the part of photoelectric conversion elements.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation imaging apparatus, a photoelectric conversion apparatus, and a radiation imaging system.
Radiation imaging devices and photoelectric conversion devices that convert radiation such as X-rays, α-rays, β-rays, and γ-rays into light of a wavelength that can be detected by a photoelectric conversion element with a scintillator such as a phosphor, and detect this light with the photoelectric conversion element And a radiation imaging system.

[0002]

2. Description of the Related Art Conventionally, a reading system using a reduction optical system and a CCD type sensor has been used as a reading system of a facsimile, a digital copying machine or an X-ray imaging apparatus. , A-S
Write i. With the development of photoelectric conversion semiconductor materials represented by (1), the development of a so-called contact type sensor in which a photoelectric conversion element and a signal processing section are formed on a large-sized substrate and read by an information source and an optical system of the same magnification is remarkable. In particular, a-Si can be used not only as a photoelectric conversion material but also as a thin film field effect transistor (hereinafter, referred to as a thin film transistor), so that a photoelectric conversion semiconductor layer and a semiconductor layer of the thin film transistor can be formed simultaneously. Has advantages.

Therefore, we have previously proposed a radiation imaging apparatus shown in FIG. 5 (Japanese Patent Laid-Open No. Hei 10-189932). Here, the description is made on the assumption that the incident radiation is an X-ray.

FIG. 5 is an overall circuit diagram showing a radiation imaging apparatus we previously proposed, FIG. 6A is a plan view of each component corresponding to one pixel of the radiation imaging apparatus of FIG. 5, and FIG. FIG. 7 is a sectional view taken along line AB in FIG. FIG. 7A shows FIG.
FIG. 7B is a plan view of each component corresponding to one pixel for signal correction output of the radiation imaging apparatus of FIG.
It is a line sectional view.

In FIG. 5, S11 to S33 are photoelectric conversion elements, in which the lower electrode side is denoted by G and the upper electrode side is denoted by D.
C11 to C33 are storage capacitors, and T11 to T33 are transfer thin film transistors. Vs is a read power supply, and Vg is a refresh power supply. All the photoelectric conversion elements S11 to S3 are connected via switches SWs and SWg, respectively.
3 G electrodes. The switch SWs is connected to the refresh control circuit RF via the inverter via the inverter, and the switch SWg is controlled to be turned on during the refresh period. One pixel is one
It is composed of a plurality of photoelectric conversion elements, a capacitor, and a thin film transistor, and its signal output is connected to a detection integrated circuit IC by a signal wiring SIG. The radiation imaging apparatus shown here divides a total of nine pixels into three blocks,
The outputs of three pixels per block are simultaneously transferred, sequentially converted to an output by the integrated circuit for detection IC through the signal wiring SIG, and output (Vout). Each pixel is two-dimensionally arranged by arranging three pixels in one block in the horizontal direction and sequentially arranging the three blocks in the vertical direction.

FIGS. 6 (a) and 6 (b) and FIGS.
(B) shows the storage capacitor C of the normal pixel and the correction pixel.
11, C13, transfer thin film transistors T11, T1
3, a plan view and a cross-sectional view of the photoelectric conversion elements S11 and S13. In the correction pixel, as shown in FIG. 7B, the storage capacitor C13, the transfer thin film transistor T13, and the upper part of CsI on the photoelectric conversion element S13. A lead plate 90 for preventing the transmission of X-rays is disposed at the center. As a result, the photoelectric conversion element S
13 are used as signal output correction outputs.

In FIG. 5, a portion surrounded by a broken line is formed on the same insulating substrate having a large area, and a plan view of a portion corresponding to the first pixel is shown in FIG. The broken line A in the figure
FIG. 6B is a cross-sectional view of the portion indicated by -B. S11
Is a photoelectric conversion element, T11 is a thin film transistor, C11 is a capacitor, and SIG is a signal wiring. FIG.
The layer configuration shown in FIG. 6A and FIG.
The configuration is the same as that shown in FIG. 6B except that a lead plate 90 is provided.

On a substrate 1, a lower metal layer 2 of Cr or the like,
An upper metal layer 6 such as an SiN film 7, an i layer 4, an n ⁺ layer 5, and Al is formed, and a silicon nitride (SiN) film 8 for passivation and a fluorescent light serving as a scintillator such as cesium iodide (CsI) are formed above the pixels. A body 9 is formed. When an X-ray (X-ray) enters from above, the X-ray is converted by the phosphor 9 into light (broken arrow), and this light enters the photoelectric conversion element. The lower metal layer 2 such as Cr of S11 of the photoelectric conversion element is a first electrode layer, the SiN film 7 is a first insulating layer,
Is a photoelectric conversion semiconductor layer, the n ⁺ layer 5 is an injection blocking layer, and the upper metal layer 6 of Al or the like is a second electrode layer.

Next, the operation of the radiation imaging apparatus will be described with reference to FIGS. FIG. 8 is a timing chart showing the operation of FIG.

First, shift registers SR1 and SR
2, H is applied to the control wirings g1 to g3 and the control wirings s1 to s3.
An i (high) level signal is applied. Then, the transfer thin film transistors T11 to T33 and the switches M1 to M3 are turned on to conduct, and the D electrodes of all the photoelectric conversion elements S11 to S33 have the GND potential (the input terminal of the integration detector Amp is G
ND potential). At the same time, the refresh control circuit RF outputs a Hi level signal and the switch SWg
Is turned on, and the G electrodes of all the photoelectric conversion elements S11 to S33 become positive potential by the refresh power supply Vg. Then, all the photoelectric conversion elements S11 to S33 enter the refresh mode and are refreshed. Next, the refresh control circuit RF outputs a Lo (low) level signal, the switches SWs are turned on, and the G electrodes of all the photoelectric conversion elements S11 to S33 are set to a negative potential by the reading power supply Vg. Then, all the photoelectric conversion elements S
11 to S33 enter the photoelectric conversion mode, and at the same time, the capacitors C11 to C33 are initialized. In this state, the control lines g1 to g3, s are controlled by the shift registers SR1 and SR2.
Lo level signals are applied to 1 to s3. Then, the transfer thin film transistors T11 to T33 and the switches M1 to M3
Is turned off, and the D electrodes of all the photoelectric conversion elements S11 to S33 are D
Although open in C, the potential is held by the capacitors C11 to C33. However, at this time, no X-rays have been incident, so that no light enters the photoelectric conversion elements S11 to S33 and no photocurrent flows. In this state, when X-rays are emitted in a pulsed manner, pass through a human body or the like, and enter a phosphor 9 such as CsI, they are converted into light, and the light enters the respective photoelectric conversion elements S11 to S33. This light contains information on the internal structure of the human body and the like. The photocurrent flowing by this light is accumulated as a charge in each of the capacitors C11 to C33, and is held even after the end of X-ray incidence.

Here, since the lead plate 90 for preventing transmission of X-rays is disposed on the photoelectric conversion elements S12 and S13 with the phosphor 9 such as CsI interposed therebetween, V2 out of the output value of Vout is obtained.
And the output value of V3 indicates zero.

Next, a high-level control pulse is applied to the control line g1 by the shift register SR1, and the control pulse is applied to the control lines s1 to s3 of the shift register SR2, and v1 is passed through the switches M1 to M3 of the transfer thin film transistors T11 to T33. To v3 are sequentially output.
Similarly, other optical signals are sequentially output under the control of the shift registers SR1 and SR2. Thereby, two-dimensional information of the internal structure of the human body or the like is obtained as v1 to v9. The operation up to this point is performed to obtain a still image, but the operation up to here is repeated to obtain a moving image.

Therefore, offset correction or external noise correction is performed using the output V2 or V3 of the photoelectric conversion element on which the lead plate 90 for preventing transmission of X-rays is disposed.

[0014]

However, in the above radiation imaging apparatus, since the lead plate is disposed on the phosphor, there are still points to be improved in terms of further cost reduction and downsizing of the apparatus. I was

[Object of the present invention] An object of the present invention is to realize offset correction and external noise correction without arranging a lead plate on a phosphor when a radiation imaging apparatus is manufactured.

[0016]

In order to solve the above-mentioned problems, a radiation imaging apparatus according to the present invention comprises a plurality of photoelectric conversion elements and light having a wavelength which can detect incident radiation by the photoelectric conversion elements. And a scintillator to convert, for some photoelectric conversion elements of the plurality of photoelectric conversion elements,
The conductive layer connected to the part of the photoelectric conversion elements is extended to cover the part of the photoelectric conversion elements, and shields light from the scintillator.

Further, the radiation imaging apparatus of the present invention has a plurality of photoelectric conversion elements, a plurality of switch elements respectively connected to the plurality of photoelectric conversion elements, and a wavelength at which incident radiation can be detected by the photoelectric conversion elements. A plurality of photoelectric conversion elements, and a wiring connecting some of the plurality of photoelectric conversion elements and the switch element is omitted.

Here, radiation refers to X-rays, α, β, γ-rays and the like as described above, and light is electromagnetic waves in a wavelength region that can be detected by a photoelectric conversion element, and includes visible light.

A photoelectric conversion device according to the present invention includes a plurality of photoelectric conversion elements and a plurality of switch elements respectively connected to the plurality of photoelectric conversion elements, and a part of the plurality of photoelectric conversion elements. In this case, the wiring connecting the switch element and the switch element is omitted.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. Here, the description will be made on the assumption that the radiation incident on the radiation imaging apparatus is an X-ray.

(First Embodiment) FIG. 1 is an overall circuit diagram of a radiation imaging apparatus according to a first embodiment of the present invention.

In the components of the whole circuit of the radiation imaging apparatus shown in FIG. 1, the same reference numerals are given to the same components as those in FIG. 5, and the detailed description will be omitted. The circuit configuration of FIG. 1 differs from that of FIG. 5 in that the light receiving portions of the photoelectric conversion elements S12 and S13 are shielded from light by metal. Therefore, as shown in FIG. 1, the photoelectric conversion elements S12 and S13 of FIG.
Are capacitors C12 'and C13', and these capacitors C12 'and C13' are used as signal output correcting elements.

FIGS. 2A and 2B show a capacitor C13,
9A and 9B are a plan view and a cross-sectional view of a transfer thin film transistor T13 and a capacitor C13 '. The same components as those in FIGS. 6A and 6B are denoted by the same reference numerals, and detailed description is omitted. The difference between the configuration of the present embodiment and the configurations of FIGS. 6A and 6B is that the capacitor C1 shown in FIG.
3. Transfer thin film transistor T13, photoelectric conversion element S1
3, the metal layer 6 is extended and disposed on the n ⁺ layer 5, and the photoelectric conversion element S13 is a capacitor C13 'as described above. . Capacitor C1 for metal layer 6
No signal light can enter the area 3 ', so this area is a capacitor on the circuit and can be used as a signal output correcting element.

As shown in FIG. 2B, on the substrate 1,
A lower metal layer 2, such as Cr, a SiN film 7, an i layer 4, an n ⁺ layer 5, and an upper metal layer 6, such as Al, are formed, and a silicon nitride (SiN) film 8 for passivation for further improving the durability. A phosphor 9 serving as a scintillator such as cesium iodide (CsI) is formed. Capacitor C1
3. Thin film transistor T13 for transfer, capacitor C1
3 'has the same layer configuration, and the capacitor C13, the transfer thin film transistor T13, and the capacitor C13' can be manufactured in the same manufacturing process.

A timing chart for explaining the operation of the radiation imaging apparatus shown in FIG. 1 according to the first embodiment of the present invention is basically the same as that shown in FIG.

Therefore, the output v of the photoelectric conversion element (capacitor) in which the light shielding material (metal layer) 6 for preventing light transmission is disposed.
The offset correction and the extraneous noise correction can be performed using 2 and v3. More specifically, the outputs v2 and v3 of the photoelectric conversion element (capacitor) in which a light-shielding member is arranged are input to a commercially available offset correction and external noise correction IC, and v2 and v4 are calculated from the values of v1 and v4 to v9. And v
By subtracting the value of 3, offset correction and external noise correction can be performed.

(Second Embodiment) FIG. 3 is an overall circuit diagram of a radiation imaging apparatus according to a second embodiment of the present invention.

In the components of the whole circuit of the radiation imaging apparatus shown in FIG. 3, the same reference numerals are given to the same components as those in FIG. 5, and detailed description will be omitted. The circuit configuration of FIG. 3 differs from that of FIG. 5 in that the metal wiring connecting the photoelectric conversion element S13 and the thin film transistor T13 is omitted. To remove the metal wiring, there are a method of deleting the metal wiring at the time of pattern design and a method of cutting with a laser or the like after forming the metal wiring.

Therefore, the output of the photoelectric conversion element is not transferred through the thin film transistor, and the output read from the photoelectric conversion element becomes zero.

FIGS. 4A and 4B show a capacitor C13,
7A and 7B are a plan view and a cross-sectional view of a transfer thin film transistor T13 and a photoelectric conversion element S13. The same components as those in FIGS. 6A and 6B are denoted by the same reference numerals, and detailed description is omitted. The configuration of the present embodiment differs from the configurations of FIGS. 6A and 6B in that the metal connecting the photoelectric conversion element S13 and the thin film transistor T13 is eliminated as described above. Therefore, the output from the photoelectric conversion element S13 is not read out and can be used as a signal output correction element.

A timing chart for explaining the operation of the radiation imaging apparatus shown in FIG. 3 according to the second embodiment of the present invention is basically the same as FIG. 8 described in the conventional example.

Accordingly, the photoelectric conversion element S1 from which the metal connecting the photoelectric conversion element and the thin film transistor is removed is removed.
2 and S13 become zero, and their outputs v2 and v13
3, the offset correction and the external noise correction can be performed. More specifically, the outputs v2 and v3 of the photoelectric conversion elements are input to offset correction and external noise correction ICs that are generally commercially available, and the values of v2 and v3 are subtracted from the values of v1 and v4 to v9. Offset correction and external noise correction can be performed.

Next, an implementation example of the radiation imaging apparatus according to the present invention and a radiation imaging system using the same will be described.

FIGS. 9A and 9B are a schematic configuration diagram and a schematic cross-sectional view, respectively, of a mounting example of the radiation imaging apparatus according to the present invention.

The photoelectric conversion element, the photoelectric conversion element for offset correction or noise correction, and the TFT are formed in an a-Si sensor substrate (or a photoelectric conversion element panel) 6011, and include a shift register SR1 and an integrated circuit for detection. I
A flexible circuit board 6010 on which C is mounted is connected. The other side of the flexible circuit board 6010 is connected to the circuit boards PCB1 and PCB2. The a-S
A plurality of i-sensor substrates 6011 are bonded on a base 6012, and a lead plate 6013 is mounted under the base 6012 constituting a large-sized photoelectric conversion device to protect a memory 6014 in a processing circuit 6018 from X-rays. Have been. On the a-Si sensor substrate 6011, a scintillator 6030 for converting X-rays into light such as visible light, for example, CsI is deposited. As shown in FIG. 9B, the whole is housed in a case 6020 made of carbon fiber.

FIG. 10 shows the X of the radiation imaging apparatus according to the present invention.
It shows an application example to a line diagnostic system.

X-rays 6060 generated by an X-ray tube 6050 serving as a radiation source pass through a chest 6062 of a patient or subject 6061 and enter a photoelectric conversion device (X-ray imaging device) 6040 having a scintillator mounted thereon. The incident X-ray includes information on the inside of the body of the patient 6061. The scintillator emits light in response to the incidence of X-rays, and photoelectrically converts the light to obtain electrical information. This information is converted into digital data, image-processed by an image processor 6070 serving as signal processing means, and can be observed on a display 6080 in the control room.

This information can be transferred to a remote place by a transmission means such as a telephone line 6090, displayed on a display 6081 such as a doctor's room in another place, or stored in a storage means such as an optical disk. It is also possible to make a diagnosis. Further, it can be recorded on a film 6110 by a film processor 6100 as recording means.

[0039]

As described above, according to the present invention,
Offset correction and external noise correction can be performed without disposing a shield such as a lead plate for shielding radiation on a part of the scintillator.

[Brief description of the drawings]

FIG. 1 is an overall circuit diagram of a first embodiment of a radiation imaging apparatus according to the present invention.

FIGS. 2A and 2B are a plan view and a cross-sectional view of signal correction pixels of the radiation imaging apparatus according to the first embodiment. FIGS.

FIG. 3 is an overall circuit diagram of a radiation imaging apparatus according to a second embodiment of the present invention.

FIG. 4 is a plan view and a sectional view of a pixel for signal correction of the radiation imaging apparatus according to the second embodiment.

FIG. 5 is an overall circuit diagram of a conventional radiation imaging apparatus.

FIG. 6 is a plan view and a sectional view of a pixel in the conventional radiation imaging apparatus.

FIG. 7 is a plan view and a cross-sectional view of a pixel for signal correction in the conventional radiation imaging apparatus.

FIG. 8 is a timing chart showing the operation of the radiation imaging apparatus of FIG.

FIG. 9 is a schematic configuration diagram and a schematic cross-sectional view of a mounting example of the radiation imaging apparatus according to the present invention.

FIG. 10 is a diagram showing an application example of the radiation imaging apparatus according to the present invention to an X-ray diagnostic system.

[Explanation of symbols]

 S11 to S33 Photoelectric conversion elements Rf11 to Rf33 Refresh thin film transistor Re11 to Re33 Initialization thin film transistor T11 to T33 Transfer thin film transistor C11 to C33 Capacitor MTX Matrix signal wiring SR1, SR2 Shift register IC Detection integrated circuit

Continued on front page F-term (reference) 2G088 EE01 FF02 GG13 GG19 GG20 JJ05 JJ09 JJ31 JJ33 JJ37 LL11 LL17 4M118 AA05 AB01 BA05 CA07 CB06 CB11 DD10 DD12 FB03 FB09 FB13 FB16 FB24 GA10 GB03 G12X11 GB11 GB09

Claims (14)

[Claims] 1. A photoelectric conversion device comprising: a plurality of photoelectric conversion elements; and a scintillator for converting incident radiation into light having a wavelength detectable by the photoelectric conversion elements. A radiation imaging apparatus that extends a conductive layer connected to the part of the photoelectric conversion elements, covers the part of the photoelectric conversion elements, and blocks light from the scintillator. 2. A plurality of photoelectric conversion elements, a plurality of switch elements respectively connected to the plurality of photoelectric conversion elements, a scintillator for converting incident radiation into light having a wavelength detectable by the photoelectric conversion elements, A radiation imaging apparatus comprising: a wiring for connecting a part of the plurality of photoelectric conversion elements and the switch element to each other. 3. The radiation imaging apparatus according to claim 1, wherein the one or more photoelectric conversion elements are photoelectric conversion elements for offset correction or noise correction. 4. The radiation imaging apparatus according to claim 3, wherein an output of the offset-correction or noise-correction photoelectric conversion element is used to output the photoelectric signal other than the offset-correction or noise-correction photoelectric conversion element. A radiation imaging apparatus for correcting an offset output value or a noise output value from a signal of a conversion element. 5. The radiation imaging apparatus according to claim 3, wherein a plurality of photoelectric conversion element panels each including the offset correction or noise correction photoelectric conversion element are arranged on the plurality of photoelectric conversion elements. A radiation imaging apparatus, comprising: 6. The radiation imaging apparatus according to claim 1, wherein the plurality of photoelectric conversion elements include a first electrode layer, a first type of carrier, and the first type. The carrier is a first insulating layer that blocks the passage of both positive and negative different second carriers, a non-single-crystal photoelectric conversion semiconductor layer, a second electrode layer, and the second electrode layer and the second A radiation imaging apparatus comprising: an injection blocking layer between photoelectric conversion semiconductor layers for preventing injection of a first type of carrier into the photoelectric conversion semiconductor layer. 7. The radiation imaging apparatus according to claim 6, wherein said photoelectric conversion semiconductor layer is made of hydrogenated amorphous silicon. 8. A radiation imaging apparatus according to claim 1, a signal processing means for processing a signal from the radiation imaging apparatus, and a signal processing means for recording a signal from the signal processing means. Recording means, display means for displaying a signal from the signal processing means, transmission processing means for transmitting a signal from the signal processing means, and a radiation source for generating the radiation. A radiation imaging system. 9. A photoelectric conversion device comprising: a plurality of photoelectric conversion elements; and a plurality of switch elements respectively connected to the plurality of photoelectric conversion elements, wherein a part of the plurality of photoelectric conversion elements and the switch element A photoelectric conversion device from which wiring to be connected has been deleted. 10. The photoelectric conversion device according to claim 9, wherein the some of the photoelectric conversion elements are photoelectric conversion elements for offset correction or noise correction. 11. The photoelectric conversion device according to claim 10, wherein an output of the photoelectric conversion element for offset correction or noise is used to output the photoelectric signal other than the photoelectric conversion element for offset correction or noise correction. A photoelectric conversion device for correcting an offset output value or a noise output value from a signal of a conversion element. 12. The photoelectric conversion device according to claim 10, wherein a plurality of photoelectric conversion element panels each including the offset correction or noise correction photoelectric conversion element are arranged on the plurality of photoelectric conversion elements. A photoelectric conversion device comprising: 13. The photoelectric conversion device according to claim 9, wherein the plurality of photoelectric conversion elements are a first electrode layer, a first type of carrier, and the first type. The carrier is a first insulating layer that blocks the passage of both positive and negative different second carriers, a non-single-crystal photoelectric conversion semiconductor layer, a second electrode layer, and the second electrode layer and the second A photoelectric conversion device, comprising: an injection blocking layer between photoelectric conversion semiconductor layers for preventing injection of a first type of carrier into the photoelectric conversion semiconductor layer. 14. The photoelectric conversion device according to claim 13, wherein the photoelectric conversion semiconductor layer is made of hydrogenated amorphous silicon.