JP2004073256A - Radiographic picture photographing apparatus, method for manufacturing the same, and imaging circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To dispense with an AEC sensor separately to thereby avoid the degrading of a picture caused by arranging, as a conventional manner, the AEC sensor on a radiographic picture photographing apparatus causing an image sensor to receive attenuated radiation and to make an apparatus body compact. <P>SOLUTION: The radiographic picture photographing apparatus comprises a first optical conversion element 8 for converting incident radiation of an electric signal and generates picture information based on the electric signal outputted from the element 8. At the lower site of the first optical conversion element 8 matched with the gap of the first element 8, a plurality of second optical conversion elements 9 for detecting the incident amount of radiation from the gap is provided. Based on detected results by the elements 9, exposure control to the incident radiation and control of the optical conversion elements are performed. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
INDUSTRIAL APPLICABILITY The present invention can be applied to an image capturing apparatus that converts incident radiation into an electric signal with an image sensor to generate image information and controls exposure to radiation by detecting the amount of incident radiation with an AEC sensor. The present invention relates to a radiographic image capturing apparatus, a method of manufacturing the same, and an imaging circuit board.
[0002]
[Prior art]
2. Description of the Related Art Conventional radiation image capturing apparatuses include a radiation detecting apparatus for capturing an image by detecting radiation transmitted through a human body in two dimensions and forming an image, and a radiation automatic exposure control apparatus (AEC) for controlling exposure of radiation incident from a radiation source. ) And are incorporated separately.
[0003]
As a typical radiation detecting apparatus for image capturing of this kind, a pixel composed of a MIS type light conversion element and a switch TFT is arranged in a matrix, and a fluorescent light for converting the radiation into visible light is provided on an incident surface of the radiation. It is common to arrange the body.
[0004]
FIG. 12 is an equivalent circuit diagram of a conventional radiation detecting device for imaging. FIG. 13 is a plan view of the radiation detecting apparatus for imaging shown in FIG.
12 and 13, reference numeral 8 denotes a semiconductor conversion element such as a light conversion element, and reference numeral 7 denotes a switch TFT, each of which constitutes a pixel. Here, 4 × 4 pixels are shown in the pixel area, but actually, for example, 2000 × 2000 pixels are arranged on the insulating substrate.
[0005]
The gate electrode of the TFT 7 is connected to a common gate line (Vg) 1, and the gate line 1 is connected to a gate driver 2 that controls ON / OFF of the TFT. Further, the source or drain electrode of each TFT 7 is connected to a common signal line (Sig line) 3, and the signal line 3 is connected to an amplifier IC 4. Further, as shown in the figure, the light conversion element driving bias line (Vs line) 5 is connected to a common electrode driver 6.
[0006]
Radiation incident on the subject is attenuated and transmitted by the subject, is converted into visible light by the phosphor layer, and this visible light is incident on the light conversion element and is converted into electric charge. This charge is transferred to the signal line 3 via the TFT 7 by a gate drive pulse applied from the gate driver 2 and read out by the amplifier IC 4. Thereafter, the charge generated in the light conversion element and not transferred is removed by the light conversion element driving bias line (Vs line) 5, and this operation is called refresh.
[0007]
FIG. 14 is a schematic cross-sectional view showing a layer structure of one pixel region (position DD ′ in FIG. 13) composed of a MIS type light conversion element and a switch TFT. An example of simultaneous formation is shown.
The MIS type light conversion element includes a first conductive layer (lower electrode) 101, a first insulating layer 102, a first semiconductor layer 103, an ohmic contact layer 105, a second conductive layer (bias line) 106, The lower electrode is connected to a source or drain electrode of the TFT 7. The TFT 7 includes a first conductive layer 101 (gate electrode layer), a first insulating layer 102 (gate insulating layer), a first semiconductor layer 103, an ohmic contact layer 105, and a second conductive layer 106 (source and Drain electrode). Each gate line is connected to an electrode layer on which a gate electrode of the TFT 7 is formed, and each signal line is connected to a layer forming source and drain electrodes. Thereafter, a protective layer (for example, SiN and an organic film) 118 and a phosphor 119 for converting radiation into visible light are formed on the upper portion.
[0008]
In addition, a radiation detecting device for image capturing in which a radiation direct conversion material represented by a-Se or the like, a storage capacitor, and a switch TFT are combined has been put to practical use.
[0009]
Next, an automatic radiation exposure control device (AEC) that controls exposure of radiation incident from a radiation source in the radiation image capturing apparatus will be described.
In general, in a radiation image capturing apparatus having two-dimensionally arranged sensors, it is necessary to adjust the incident radiation dose for each subject or for each capturing (AEC control). Conventionally, an AEC control sensor is provided separately from the radiation detecting device for imaging. A plurality of thin AEC sensors with a radiation attenuation of about 5% are separately provided on the front of the radiation detecting device for imaging, and the output of these AEC sensors is used to stop the incidence of radiation and to adjust the radiation dose suitable for imaging. I was getting it. As the AEC sensor used here, one that directly extracts radiation as electric charge in an ion chamber or one that converts it into visible light through a phosphor, extracts it outside with an optical fiber, and converts it into electric charge with a photomultiplier is used. Have been. FIG. 15 shows an image diagram of a radiation detecting device for image photographing and a radiation automatic exposure control device (AEC) which constitute a conventional radiation image photographing device.
[0010]
[Problems to be solved by the invention]
However, as described above, in a two-dimensionally arranged radiation detecting apparatus for image capturing, when an AEC sensor is separately provided to adjust the amount of incident radiation (AEC), the arrangement of the sensor becomes a problem. That is, since information necessary for AEC is generally located at the center of the subject, an AEC sensor with extremely low radiation attenuation is needed to arrange the AEC sensor so as not to hinder imaging by the radiation detecting device for imaging. It becomes necessary and raises the cost of the entire apparatus.
[0011]
In addition, since there is no sensor having no attenuation at all, deterioration of the image quality of a very important part image in the diagnosis of the center of the subject is inevitable. Further, such a separately provided AEC sensor is disadvantageous in reducing the size of a radiographic image capturing apparatus that is portable and capable of capturing images of various parts.
[0012]
The present invention has been made in view of the above problems, and does not require a separate detection unit (AEC sensor). Radiation attenuated by arranging the detection unit on a radiation image capturing apparatus as in the related art is not required. To the conversion means (image sensor) to prevent the image quality from deteriorating, and to contribute to downsizing of the apparatus body.
[0013]
[Means for Solving the Problems]
In order to achieve such an object, a radiographic image capturing apparatus according to a first aspect of the present invention includes a conversion unit that converts incident radiation into an electric signal, and based on an electric signal output from the conversion unit. A radiation image photographing apparatus in which image information is generated by detecting the amount of radiation incident on the lower part of the conversion means, based on the detection result by the detection means, The exposure control is performed.
[0014]
Further, a method of manufacturing a radiation image capturing apparatus according to a second aspect of the present invention includes a radiation image having a plurality of conversion units for converting incident radiation into electric signals and a plurality of detection units for detecting the amount of incident radiation. A method of manufacturing a photographing device, wherein the detecting means is formed below the converting means.
[0015]
Further, an imaging circuit board according to a third aspect of the present invention includes a switching element for switching an output operation of an electric signal from a conversion unit that converts incident radiation into an electric signal, and a detection element for detecting an incident amount of the radiation. Wherein the switching element and the detection element are formed in the same layer.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
<First embodiment>
As a first embodiment of the present invention, an AEC sensor (second light conversion element) is formed at the same time as a switch TFT in an image capturing radiation detection device constituting a radiation image capturing device, and an organic insulating film is formed thereon. The MIS-type light conversion element (first light conversion element) is stacked with the interposition therebetween. An example in which the light absorption layer in the gap between the MIS type light conversion elements (first light conversion elements) for capturing an image is made thinner so that light enters the gap will be described with reference to the drawings.
[0017]
FIG. 1 is a schematic equivalent circuit diagram of the radiation image capturing apparatus of the present embodiment. 2 and 3 are schematic plan views of the radiation image capturing apparatus according to the present embodiment. FIG. 4A is a schematic cross-sectional view of one pixel region (position AA ′ in FIGS. 2 and 3) of the radiographic image capturing apparatus of the present embodiment. FIG. 4B is a schematic cross-sectional view of one pixel region (a-a ′ position in FIG. 3) of the radiographic image capturing apparatus of the present embodiment.
[0018]
In FIGS. 1, 2 and 3, reference numeral 8 denotes a semiconductor conversion element such as a first light conversion element, and reference numeral 7 denotes a switch TFT, each of which constitutes a pixel. A second light conversion element 9 is provided over a plurality of pixels, and is connected to an AEC sensor readout device 10, an AEC sensor control device (1) 11, and an AEC sensor control device (2) 12.
[0019]
In the plan views of FIGS. 2 and 3, the pixel area is 3 × 3 pixels. In actuality, for example, 2000 × 2000 pixels are arranged on the insulating substrate. Further, the second light conversion element has a shape extending over 2 × 2 pixels, but in practice, for example, one second light conversion element extends over 200 × 200 pixels, and at least three or more light conversion elements are provided in the panel. Be placed.
[0020]
The first light conversion element 8 and the switch TFT 7 are the same as in the conventional example. The gate electrode of the TFT 7 is connected to a common gate line (Vg) 1, and the gate line is a gate driver for controlling ON / OFF of the TFT. 2 are connected. Further, the source or drain electrode of each TFT 7 is connected to a common signal line (Sig line) 3, and the signal line 3 is connected to an amplifier IC 4. Further, as shown in the figure, the light conversion element driving bias line (Vs line) 5 is connected to a common electrode driver 6.
[0021]
The source line 14 and the gate line 15 of the second light conversion element 9 are connected to the AEC sensor control device (1) 11 and the AEC sensor control device (2) 12, respectively. In addition, it is possible to always output charges according to the amount of incident light. Therefore, a constant potential is always applied. The electric charge detected by the second light conversion element 9 is amplified by the AEC sensor readout device 10 via the drain line 13, and the output is added to detect the total incident amount of radiation.
[0022]
Next, the layer configuration of the radiation image capturing apparatus according to the present embodiment will be described with reference to FIG.
First, a switch TFT 7 and a second light conversion element 9 used as an AEC sensor are formed on a glass substrate 100. First, a first conductive layer 101 is formed by a sputtering method, and a gate electrode and a gate line (for example, AlNd / Mo 2500A) of the TFT 7 and the second light conversion element 9, and a first insulating layer 102 (for example, SiN 3000A), a first semiconductor layer (first light absorbing layer) 103 (for example, a-Si 1500A), and a second insulating layer 104 (for example, SiN 2000A) are continuously formed by a CVD method, and a second insulating layer is formed. A layer is formed on the gate electrode and the gate line as a protective film between each source and drain by back surface exposure.
[0023]
Subsequently, a first ohmic contact layer 105 (for example, a-Si (n +) 200A) is formed by a CVD method, and a second conductive layer 106 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method. A drain electrode and a wiring are formed. Further thereon, a third insulating layer 107 (for example, an organic film BCB (benzocyclobutene)) as a protective layer is formed. As described above, according to the present embodiment, by forming the TFT 7 and the second light conversion element 9 at the same time, an imaging circuit substrate including the TFT 7 and the second light conversion element 9 on the same layer is formed. .
[0024]
A third conductive layer 108 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method, is connected to a source or drain electrode of the TFT 7 through a contact hole, and is used as a lower electrode of the first light conversion element 8 for each pixel. To separate. A fourth insulating layer 109 (eg, SiN 2000A), a second semiconductor layer (second light absorbing layer) 110 (eg, a-Si 5000A), and a second ohmic contact layer 111 (eg, a-Si ( n +) 200 A) is continuously formed by a CVD method.
[0025]
Further, a fourth conductive layer 112 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method, a bias line of the first light conversion element 8 is formed, and then a transparent conductive layer 113 (for example, ITO 200A) is formed by a sputtering method. ) Is formed. The transparent conductive layer 113 and the second ohmic contact layer 111 are formed in stripes along the source / drain lines of the second light conversion element 9 so that light is incident on the second light conversion element 9 (light propagation region). Then, the second semiconductor layer (second light absorption layer) 110 is etched by a wet and dry method to form a depression in the second semiconductor layer.
[0026]
At this time, it is preferable to completely eliminate the second semiconductor layer (second light absorption layer) 110 in the light propagation region and form an aperture pattern because the amount of light incident on the second light conversion element 9 increases. However, as shown in the figure, even if it is in a half-etched state, it can function as long as the remaining film amount is such that the absorption in the second semiconductor layer (second light absorption layer) 110 is 50% or less.
[0027]
In the present embodiment, the light propagation region is formed in a stripe shape along the source / drain line of the second light conversion element 9 (see FIG. 4A), but the second semiconductor layer (second May be separated from each other. Thereafter, a protective layer 118 (for example, SiN and an organic film) and a phosphor 119 are formed on the upper surface.
[0028]
In the present embodiment, an MIS light conversion element is used as the first light conversion element 8, but a PIN light conversion element may of course be used. Further, in the present embodiment, a TFT-type light conversion element composed of a gate, a source, and a drain is used as the second light conversion element 9, but sufficient performance can be obtained even with a configuration excluding the gate. When the gate wiring 15 of the second light conversion element is arranged in the gap between the lower electrodes of the first light conversion element as shown in FIG. 2, the occurrence of parasitic capacitance between the gate wiring 15 and the first light conversion element is reduced. Although it can be avoided and is advantageous in terms of noise and the like, if it is disposed immediately below the lower electrode of the first light conversion element as shown in FIGS. 3 and 4B, the lower electrode of the first light detection element The signal can be improved because the area can be widened. In this embodiment, as shown in FIGS. 2 and 3, the first light conversion element 8 is also formed above the TFT 7, thereby increasing the aperture ratio of the first light conversion element 8. Although it is ensured, the region above the TFT 7 may be removed from the region where the first light conversion element 8 is formed.
[0029]
According to this embodiment, since the AEC sensor (second light conversion element) is simultaneously formed on the substrate of the radiation detecting apparatus for image capturing, it is not necessary to separately provide an automatic radiation exposure control apparatus (AEC), and the radiation image is not required. The imaging device can be downsized.
Further, in the present embodiment, the manufacturing process of the substrate of the radiation detecting apparatus for image capturing is used as it is, which is effective in terms of cost.
Until now, the AEC sensor was provided separately on the front surface of the radiation detecting device for imaging, but in the present embodiment, the gap is used without affecting the aperture ratio of the first light conversion element for imaging. Since the AEC sensor (second light conversion element) is formed, there is no image degradation.
[0030]
Further, in the present embodiment, the second light conversion element in a narrow area called the gap between the first light conversion elements is formed over a plurality of pixels (for example, 200 × 200 pixels) and is electrically connected. Can get enough output.
Also, the AEC sensor can be used at the same time as a radiation monitor.
The radiation monitor detects ON and OFF of the radiation incident on the radiation detecting device for imaging, and controls the detection of the radiation detecting device for imaging, and is not limited to the first embodiment. It can be used in all the embodiments.
[0031]
<Second embodiment>
Next, a second embodiment of the present invention will be described.
As a second embodiment of the present invention, an AEC sensor (second light conversion element) is formed at the same time as a switch TFT in an image capturing radiation detection device constituting a radiation image capturing device, and an organic insulating film is formed thereon. When laminating the PIN light conversion element (first light conversion element) through the gap, the gap between the element is set such that light enters the gap between the PIN light conversion element (first light conversion element) for image capturing. An example of removing the light absorbing layer will be described with reference to the drawings.
[0032]
FIG. 5 is a schematic equivalent circuit diagram of the radiation image capturing apparatus of the present embodiment. FIGS. 6 and 7 are schematic plan views of the radiation image capturing apparatus of the present embodiment. FIG. 8A is a schematic cross-sectional view of one pixel region (the position of BB ′ in FIGS. 6 and 7) of the radiographic image capturing apparatus of the present embodiment. FIG. 8B is a schematic cross-sectional view of one pixel region (bb 'position in FIG. 7) of the radiographic image capturing apparatus of the present embodiment.
[0033]
5, 6, and 7, reference numeral 8 denotes a semiconductor conversion element such as a first light conversion element, and reference numeral 7 denotes a switch TFT, each of which constitutes a pixel. A second light conversion element 9 is provided over a plurality of pixels, and is connected to an AEC sensor readout device 10, an AEC sensor control device (1) 11, and an AEC sensor control device (2) 12.
[0034]
In the plan views of FIGS. 6 and 7, the pixel area is 3 × 3 pixels. In actuality, for example, 2000 × 2000 pixels are arranged on the insulating substrate. Further, the second light conversion element has a shape extending over 2 × 2 pixels, but in practice, for example, one second light conversion element extends over 200 × 200 pixels, and at least three or more light conversion elements are provided in the panel. Be placed.
[0035]
The first light conversion element 8 and the switch TFT 7 are the same as in the conventional example. The gate electrode of the TFT 7 is connected to a common gate line (Vg) 1, and the gate line is a gate driver for controlling ON / OFF of the TFT 7. 2 are connected. Further, the source or drain electrode of each TFT 7 is connected to a common signal line (Sig line) 3, and the signal line 3 is connected to an amplifier IC 4. Further, as shown in the figure, the light conversion element driving bias line (Vs line) 5 is connected to a common electrode driver 6.
[0036]
The source line 14 and the gate line 15 of the second light conversion element 9 are connected to the AEC sensor control device (1) 11 and the AEC sensor control device (2) 12, respectively. In addition, it is possible to always output charges according to the amount of incident light. Therefore, a constant potential is always applied. The electric charge detected by the second light conversion element 9 is amplified by the AEC sensor readout device 10 via the drain line 13 and the output is added to detect the total amount of radiation.
[0037]
Next, the layer configuration of the radiation image capturing apparatus according to the present embodiment will be described with reference to FIG.
First, a switch TFT 7 and a second light conversion element 9 used as an AEC sensor are formed on a glass substrate 100. A first conductive layer 101 is formed by a sputtering method, and a gate electrode and a gate line (for example, AlNd / Mo 2500A) of a TFT and a second light conversion element, and a first insulating layer 102 (for example, SiN 3000A) is formed thereon. Then, a first semiconductor layer (first light absorption layer) 103 (for example, a-Si 5000A) is continuously formed by a CVD method.
[0038]
Here, it is desirable that the transfer rate of the TFT 7 is faster, and therefore, the first semiconductor layer 103 is desirably a thin film. Therefore, only the TFT portion is thinned by half etching. Subsequently, a first ohmic contact layer 105 (for example, a-Si (n +) 200A) is formed by a CVD method, and a second conductive layer 106 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method. A drain electrode and a wiring are formed.
[0039]
A second insulating layer 104 (for example, SiN 2000A) is formed thereon by a CVD method to protect a channel portion of the TFT 7 in particular, and a third insulating layer 107 (for example, an organic film BCB) serving as a protective layer is further formed. (Benzocyclobutene)).
[0040]
A third conductive layer 108 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method, is connected to a source or drain electrode of the TFT 7 through a contact hole, and is used as a lower electrode of the first light conversion element. Separate for each pixel so that it does not overlap. An N-type semiconductor layer 114 (for example, a-Si (P) 1000A), a high-resistance semiconductor layer (second light absorption layer) 115 (for example, a-Si 5000A), and a P-type semiconductor layer 116 (for example, a-Si) (N) 1000A) is continuously formed by a CVD method. Further, a fourth conductive layer 112 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method to form a bias line of the first light conversion element.
[0041]
The N-type semiconductor layer 114, the high-resistance semiconductor layer (second light absorption layer) 115, and the P-type semiconductor layer 116 are used to separate each pixel and secure a light propagation path to the second light conversion element 9. Dry etching is performed in a shape along the lower electrode of the first light conversion element (element separation). In this embodiment, as shown in FIG. 8, an N-type semiconductor layer 114, a high-resistance semiconductor layer (second light absorbing layer) 115, and a P-type semiconductor layer 116 are provided for each pixel as a lower electrode of the first light conversion element. Although the elements were separated in a shape along the first light conversion element, it is better to form the light propagation region in a stripe shape along the source / drain lines of the second light conversion element 9 as in the first embodiment. A wide aperture ratio is preferable. Thereafter, a protective layer 118 (for example, SiN and an organic film) and a phosphor 119 are formed on the upper surface.
[0042]
In the present embodiment, a PIN light conversion element is used as the first light conversion element, but a MIS light conversion element may of course be used. Further, in the present embodiment, a TFT-type light conversion element including three gates, a source, and a drain, is used as the second light conversion element. However, sufficient performance can be obtained with a configuration excluding the gate.
[0043]
If the gate wiring of the second light conversion element is arranged in the gap between the lower electrodes of the second light conversion element as shown in FIG. 6, the occurrence of parasitic capacitance between the gate electrode 15 and the first light conversion element is avoided. This is advantageous in terms of noise and the like, but if it is disposed immediately below the lower electrode of the second light conversion element as shown in FIGS. 7 and 8B, the lower electrode of the first light detection element The signal can be improved because the area can be widened. Further, in the present embodiment, the upper part of the TFT 7 is excluded from the region where the first light conversion element 8 is formed. However, in consideration of the light leakage current of the TFT 7, FIG. As shown in (1), a first light conversion element 8 may be formed also above the TFT 7 to reduce light incidence on the TFT.
[0044]
According to this embodiment, since the AEC sensor (second light conversion element) is simultaneously formed on the substrate of the radiation detecting apparatus for image capturing, it is not necessary to separately provide an automatic radiation exposure control apparatus (AEC), and the radiation image is not required. The imaging device can be downsized.
Further, according to the present embodiment, the manufacturing process of the substrate of the radiation detecting apparatus for image capturing is used as it is, which is effective in terms of cost.
Further, the AEC sensor is provided separately in front of the radiation detecting device for imaging, but in the present embodiment, the gap is increased without affecting the aperture ratio of the first light conversion element for imaging. Since the AEC sensor (second light conversion element) is formed by using this, there is no reduction in image.
Furthermore, according to the present embodiment, the second light conversion element in a narrow area called the gap between the first light conversion elements is formed over a plurality of pixels (for example, 200 × 200 pixels) and is electrically connected. A sufficient output as an AEC sensor can be obtained.
[0045]
Next, a third embodiment of the present invention will be described.
<Third embodiment>
As a third embodiment of the present invention, in a radiation detecting apparatus for radiography constituting a radiographic imaging apparatus, a switch TFT 7 and an amorphous selenium (a-Se) or a gallium arsenide (GaAs) are interposed on the switch TFT 7 via an organic insulating film. )), An example of forming an AEC sensor (second radiation conversion element) in a gap between the first radiation conversion elements when forming a radiation direct detection material (first radiation conversion element). This will be described with reference to the drawings.
[0046]
FIG. 9 is a schematic equivalent circuit diagram of the radiation image capturing apparatus of the present embodiment. FIG. 10 is a schematic plan view of the radiographic image capturing apparatus of the present embodiment. FIG. 11 is a schematic cross-sectional view of one pixel region (the position CC ′ in FIG. 10) of the radiation image capturing apparatus of the present embodiment.
[0047]
The operation of the present embodiment will be described with reference to FIGS. Reference numeral 17 denotes a semiconductor conversion element such as a first radiation conversion element, and 7 denotes a switch TFT, each constituting a pixel. The second radiation conversion element 18 extending over a plurality of pixels shares the bias line 5 with the first radiation conversion element 17, and the lower electrode wiring 20 unique to the second radiation conversion element 18 is connected to the readout device 10 for the AEC sensor. It is connected to the. Actually, for example, 2000 × 2000 pixels are arranged on an insulating substrate. Further, as for the second radiation conversion element 18, for example, one second light conversion element extends over 200 × 200 pixels, and at least three or more are disposed in the panel.
[0048]
The radiation incident on the subject is attenuated by the subject, passes through, and enters the first radiation conversion element 17 (for example, a-Se). When radiation enters a-Se, positive and negative charges corresponding to the incident radiation energy are generated by the photoconductive effect. When a voltage of several kilovolts is applied to both ends of a-Se using the bias line 5 connected to the common electrode driver 6, the generated charges can be taken out as a light current along the electric field, and the first image pickup for image pickup is performed. The charge generated by the radiation conversion element 17 is stored in the storage capacitor 19 disposed on the insulating substrate. The stored charges are transferred to the signal line 3 via the TFT 7 and read out by the amplifier IC 4. The gate electrode of the TFT 7 is connected to a common gate line (Vg) 1, and the gate line 1 is connected to a gate driver 2 that controls ON / OFF of the TFT.
[0049]
On the other hand, the second radiation conversion element 18 is sandwiched between the bias line 5 (upper electrode) and the lower electrode wiring 20 and can always output a charge according to the amount of incident light by applying a constant potential. The generated charges are directly connected to and amplified by the AEC sensor readout device 10 via the lower electrode, and the total amount of radiation is detected by adding the outputs.
[0050]
Next, the layer configuration of the radiation image capturing apparatus according to the present embodiment will be described with reference to FIG.
First, a first conductive layer 101 is formed on a glass substrate 100 by a sputtering method, and a gate electrode and a gate line of the TFT 7 and a lower electrode of a second radiation conversion element storage capacitor are formed. (For example, AlNd / Mo 2500A), a first insulating layer 102 (for example, SiN 3000A), a first semiconductor layer (first light absorbing layer) 103 (for example, a-Si 1500A), and a second insulating layer 104 (for example, SiN 2000A) is continuously formed by a CVD method, and a second insulating layer is formed on the first conductive layer as a protective film between a TFT source and a drain by back surface exposure.
[0051]
Subsequently, a first ohmic contact layer 105 (for example, a-Si (n +) 200A) is formed by a CVD method, and a second conductive layer 106 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method. A drain electrode and a wiring, and a lower electrode wiring (20) of the second radiation conversion element are formed. Further thereon, a third insulating layer 107 (for example, an organic film BCB (benzocyclobutene)) as a protective layer is formed. The contact hole on the source or drain electrode of the TFT 7 and the third insulating layer at the lower electrode of the second radiation conversion element are removed by etching.
[0052]
A third conductive layer 108 (for example, Cu2000A) is formed by a sputtering method, is connected to a source or drain electrode of a TFT through a contact hole, and is separated for each pixel as a lower electrode of the first light conversion element. A-Se is formed thereon. Further, a fourth conductive layer 112 (for example, Mo / Al / Mo 4000A) is formed by a sputtering method. Thereafter, a protective layer 118 (for example, SiN and an organic film) is formed on the upper surface.
[0053]
Further, in this embodiment, the charge generated by the second radiation conversion element used as the AEC sensor is directly read out via the lower electrode wiring 20, but if a unique electrode is formed on the first conductive layer, accumulation / readout is also possible. It becomes. Further, in the present embodiment, as shown in FIG. 10, the upper part of the TFT 7 is excluded from the formation region of the first radiation conversion element (lower electrode of the first radiation conversion element) 17. When the leakage current is taken into consideration, the first radiation conversion element 17 may be formed also above the TFT 7 to reduce light incidence on the TFT as shown in FIG. 4A of the first embodiment. .
[0054]
According to this embodiment, since the AEC sensor (second radiation conversion element) is simultaneously formed on the substrate of the radiation detecting apparatus for image capturing, it is not necessary to separately provide an automatic radiation exposure control apparatus (AEC), and the radiation image is not required. The imaging device can be downsized.
Further, in the present embodiment, the manufacturing process of the substrate of the radiation detecting apparatus for image capturing is used as it is, which is effective in terms of cost.
Further, the AEC sensor is provided separately on the front surface of the radiation detecting device for imaging, but in the present embodiment, the gap is increased without affecting the aperture ratio of the first radiation conversion element for imaging. Since the AEC sensor (second radiation conversion element) is used to form the image, there is no reduction in image.
Furthermore, according to the present embodiment, the second radiation conversion element in a narrow area called the gap between the first radiation conversion elements is formed over a plurality of pixels (for example, 200 × 200 pixels) and is electrically connected. A sufficient output as an AEC sensor can be obtained.
[0055]
As described above, according to the embodiment of the present invention, low-cost and compact radiation having a function of detecting and adjusting the amount of incident radiation with sufficient sensitivity without causing image degradation (AEC). This realizes an image capturing device.
Further, the present invention is not limited to these embodiments, and can be used in appropriate combinations.
[0056]
【The invention's effect】
According to the present invention, since the detection unit is provided below the conversion unit, there is no need to prepare a separate detection unit other than the radiation image capturing apparatus. Further, by arranging the detection means on the radiation image capturing apparatus as in the related art, it is possible to prevent the conversion means from receiving the attenuated radiation and to prevent the image quality from deteriorating. Further, since the detection means and the conversion means are arranged in a multilayer structure, it can contribute to downsizing of the apparatus main body.
[Brief description of the drawings]
FIG. 1 is a schematic equivalent circuit diagram of a radiation image capturing apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic plan view of the radiation image capturing apparatus according to the first embodiment of the present invention.
FIG. 3 is a schematic plan view of the radiation image capturing apparatus according to the first embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view of one pixel region of the radiation image capturing apparatus according to the first embodiment of the present invention.
FIG. 5 is a schematic equivalent circuit diagram of a radiographic image capturing apparatus according to a second embodiment of the present invention.
FIG. 6 is a schematic plan view of a radiation image capturing apparatus according to a second embodiment of the present invention.
FIG. 7 is a schematic plan view of a radiographic image capturing apparatus according to a second embodiment of the present invention.
FIG. 8 is a schematic cross-sectional view of one pixel region of a radiation image capturing apparatus according to a second embodiment of the present invention.
FIG. 9 is a schematic equivalent circuit diagram of a radiographic image capturing apparatus according to a third embodiment of the present invention.
FIG. 10 is a schematic plan view of a radiation image capturing apparatus according to a third embodiment of the present invention.
FIG. 11 is a schematic sectional view of one pixel region of a radiographic image capturing apparatus according to a third embodiment of the present invention.
FIG. 12 is an equivalent circuit diagram of a conventional radiation detecting apparatus for image capturing.
FIG. 13 is a plan view of a conventional radiation detecting apparatus for imaging.
FIG. 14 is a cross-sectional view schematically illustrating a layer configuration of one pixel region including a MIS light conversion element and a switch TFT.
FIG. 15 is an image diagram of a radiation detecting device for image photographing and a radiation automatic exposure control device (AEC) which constitute a radiation image photographing device in a conventional example.
[Explanation of symbols]
1 Gate wiring
2 Gate driver
3 signal lines
4 Amplifier IC
5 Bias wiring
6 Common electrode driver
7 TFT
8 First light conversion element
9 Second light conversion element
10 Readout device for AEC sensor
11 Control device for AEC sensor (1)
12 Control device for AEC sensor (2)
13 Drain line of the second light conversion element
14 Source line of the second light conversion element
15 Gate line of the second light conversion element
16 Light propagation area
17 First radiation conversion element
18 Second radiation conversion element
19 Storage capacitor
20 Lower electrode wiring of the second radiation conversion element
100 glass substrate
101 first conductive layer
102 First insulating layer
103 First semiconductor layer
104 Second insulating layer
105 First ohmic contact layer
106 second conductive layer
107 Third insulating layer
108 Third conductive layer
109 Fourth insulating layer
110 second semiconductor layer
111 Second ohmic contact layer
112 fourth conductive layer
113 Transparent conductive layer
114 N-type semiconductor layer
115 High resistance semiconductor layer
116 P-type semiconductor layer
117 Direct conversion material
118 protective layer
119 phosphor

Claims (16)

A radiation image capturing apparatus having a conversion unit that converts incident radiation into an electric signal, wherein image information is generated based on the electric signal output from the conversion unit,
In the lower part of the converting means, a detecting means for detecting the incident amount of the radiation,
A radiation image capturing apparatus, wherein exposure control for incident radiation is performed based on a detection result by the detection unit. The radiation image capturing apparatus according to claim 1, further comprising a plurality of the conversion units, wherein the detection unit is provided in alignment with a gap between the plurality of conversion units. The apparatus according to claim 1, wherein the control unit controls the conversion unit based on a result of the detection unit. The apparatus according to claim 1, wherein the conversion unit includes a phosphor that converts incident radiation into visible light and a first conversion element that converts the visible light converted by the phosphor into an electric signal. 4. The radiographic image capturing apparatus according to any one of the preceding claims. The radiation image capturing apparatus according to claim 1, wherein the conversion unit includes a first conversion element that converts incident radiation into an electric signal. The radiation image capturing apparatus according to claim 1, wherein the detection unit includes a second conversion element that converts visible light converted from radiation by the phosphor into an electric signal. The radiation image capturing apparatus according to claim 4, wherein the detection unit is formed at a lower part of the first conversion element group formed in a predetermined closed area. 6. The conversion device according to claim 4, wherein the first conversion element includes a conversion layer, and the conversion layer is thinner in a portion above the detection means than in other portions. Radiation imaging device. The radiation image capturing apparatus according to claim 4, wherein the first conversion element includes a conversion layer, and the conversion layer has an opening formed above the detection unit. The radiation image capturing apparatus according to claim 4, wherein the first conversion element is a MIS type semiconductor conversion element. The radiation image capturing apparatus according to claim 6, wherein the second conversion element is a MIS type semiconductor conversion element. The radiation image capturing apparatus according to claim 4, wherein the first conversion element is a PIN-type semiconductor conversion element. The radiation image capturing apparatus according to claim 1, wherein the detection unit is formed on the same layer as a switching element that switches an output operation of the electric signal from the conversion unit. The radiation image capturing apparatus according to claim 4, wherein the first conversion element contains amorphous selenium (a-Se) or gallium arsenide (GaAs). A method of manufacturing a radiation image capturing apparatus having a plurality of converting means for converting incident radiation into an electric signal and a plurality of detecting means for detecting an amount of incident radiation,
A method for manufacturing a radiation image capturing apparatus, wherein the detecting means is formed below the converting means. Includes a switching element that switches an output operation of an electric signal from a conversion unit that converts incident radiation into an electric signal, and a detection element that detects an incident amount of radiation,
An imaging circuit board, wherein the switching element and the detection element are formed in the same layer.

Images