JP6470508B2 - Radiation imaging apparatus and radiation imaging system - Google Patents

Description

  The present invention relates to a radiation imaging apparatus and a radiation imaging system.

In recent years, a manufacturing technique of a liquid crystal panel using a TFT (thin film transistor) has progressed, and a display screen has been enlarged with an increase in the size of the panel. This manufacturing technique is applied to a large area sensor (detection device) having a conversion element such as a photoelectric conversion element constituted by a semiconductor and a switch element such as a TFT. Area sensors are used in the field of radiation detection devices such as medical X-ray detection devices in combination with a phosphor that converts the wavelength of radiation such as X-rays into light such as visible light. Recently, it has been proposed to incorporate the following two functions in a radiation detection apparatus.
-Automatic detection function of radiation-Automatic exposure control function of radiation In Patent Document 1, in one pixel, an imaging photoelectric conversion element connected to a signal wiring via a TFT is formed in the same layer as the imaging photoelectric conversion element. In the arranged photoelectric conversion element for monitoring (for automatic radiation exposure control), a configuration in which a bias line is shared has been proposed. When the radiation converted into visible light by the phosphor layer is incident on the monitor photoelectric conversion element, the visible light is converted into electric charge and transported to the monitor signal processing circuit section through the wiring. The transported charge amount is measured in real time as an X-ray irradiation amount, and when the set amount is reached, a signal is sent to the X-ray source to stop the X-ray irradiation. Thereafter, the charge accumulated in the imaging photoelectric conversion element is read. This makes it possible to incorporate an automatic radiation exposure control function in the detection device.

Patent No. 4659337

  However, in the configuration of Patent Document 1, the bias lines for the imaging photoelectric conversion element and the monitoring photoelectric conversion element are shared. If the electric field applied to the imaging photoelectric conversion element is set to increase the saturation dose, the electric field applied to the monitoring photoelectric conversion element also becomes strong, which may reduce the detection accuracy. The present invention provides a radiation imaging apparatus that is advantageous for realizing an increase in saturation dose of an imaging photoelectric conversion element and an improvement in detection accuracy of a monitoring photoelectric conversion element.

One aspect of the present invention provides a plurality of first conversion elements having a first electrode and a second electrode for generating an imaging signal corresponding to radiation, a third electrode for detecting radiation, and a first electrode A plurality of second conversion elements having four electrodes, and a first potential difference for resetting the first conversion element between the first electrode and the second electrode of the first conversion element. between the marks pressurized to, and the first of the third electrode and the fourth electrode of said second potential difference the second conversion element for the second conversion element is reset smaller than the potential difference in the a potential difference application means you applied to, the second based on a signal from the conversion element have a, a measurement unit for measuring the dose of the radiation, said potential difference applying means, said first transducer A first bias line connected to the first electrode and a third electrode of the second conversion element A first monitoring wiring connected to the fourth electrode, and the second bias wiring and the first monitoring wiring overlap in plan view. are arranged so characterized that you have.

  ADVANTAGE OF THE INVENTION According to this invention, the radiation imaging device advantageous to implement | achieve the expansion of the saturation dose of the photoelectric conversion element for imaging, and the improvement of the detection accuracy of the photoelectric conversion element for monitoring can be provided.

FIG. 2 is a plan view of the radiation imaging apparatus according to the first embodiment. FIG. 2 is a plan view of a pixel according to the first embodiment. FIG. 3 is a cross-sectional view of a pixel in Embodiment 1. An example of an input circuit of a signal processing circuit for imaging. FIG. 6 is a plan view of a radiation imaging apparatus according to a second embodiment. FIG. 6 is a plan view of a pixel according to the second embodiment. FIG. 4 is a cross-sectional view of a pixel according to a second embodiment. FIG. 6 is a plan view of a radiation imaging apparatus according to a third embodiment. FIG. 6 is a plan view of a pixel according to the third embodiment. FIG. 6 is a cross-sectional view of a pixel according to a fourth embodiment. FIG. 6 is a plan view of a radiation imaging apparatus according to a fourth embodiment. FIG. 6 is a plan view of a pixel according to the fourth embodiment. The figure which shows the structural example of a radiation imaging system.

  First, the principle of the present invention will be described. In an area sensor having a conversion element such as a photoelectric conversion element and a switch such as a TFT, reading of signals from the conversion element is controlled by the switch. An imaging photoelectric conversion element for generating an imaging signal is referred to as a first conversion element. The photoelectric conversion element for imaging should have a large saturation dose from the viewpoint of imaging sensitivity. In order to increase the saturation dose, it is advantageous to increase the voltage applied between the electrodes of the conversion element during reading to increase the electric field applied to the conversion element.

  On the other hand, a photoelectric conversion element for monitoring used for detecting radiation or measuring radiation dose is arranged in the area sensor together with the first conversion element. The monitor photoelectric conversion element is referred to as a second conversion element. One of the characteristics required for the second conversion element is high detection accuracy. A dark current flows through the photoelectric conversion element together with a signal corresponding to the intensity of incident light. When the electric field strength applied to the second conversion element is large, the dark current also increases, and the detection accuracy of the radiation dose deteriorates due to the influence of the dark current. For this reason, the electric field strength applied to the second conversion element is preferably as small as possible within a range in which linearity is maintained with respect to incident light. Further, in the case where the second conversion element is configured to be directly connected to the wiring without using a switch, when visible light enters the conversion element, the generated charge is immediately accumulated without accumulating in the conversion element. Since the charge is transported through the wiring, the conversion element does not saturate. Therefore, a strong electric field for expanding the saturation dose as required for the first conversion element is unnecessary. From the above, in order to make the operation of each photoelectric conversion element for imaging and monitoring good, the configuration in which the voltage applied to the conversion element can be appropriately set is described below with reference to the accompanying drawings. I will explain. In addition, in this specification, radiation is a beam having energy of the same degree or more, for example, X-rays, β-rays, γ-rays, etc., which are beams formed by particles (including photons) emitted by radiation decay, such as X Lines, particle beams, cosmic rays, etc. are also included.

(Embodiment 1)
First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an equivalent circuit diagram showing a circuit configuration of the radiation detection apparatus according to the present embodiment. Here, FIG. 1 shows an example in which pixels of 6 rows and 6 columns are provided, but the number is not limited to this, and, for example, 2000 × 2000 pixels may be provided.

  In the present embodiment, the imaging photoelectric conversion element 15 is connected to the imaging signal processing circuit 51 via a TFT (thin film transistor) 16 that operates as a switch and a signal wiring 30. The monitor photoelectric conversion element 17 for automatic radiation detection and radiation automatic exposure control is connected to the monitor signal processing circuit 55 via the first monitor wiring 31. In the radiation imaging apparatus according to the present embodiment, the first imaging pixel 1 having the imaging photoelectric conversion element 15 and the TFT 16 and the first monitoring wiring 31 are routed in the pixel. Have imaging regions arranged in a matrix. The first monitoring element 2 provided with the monitoring photoelectric conversion element 17 is arranged in place of the pixels in the imaging region. Here, the arrangement of the first imaging pixel 1, the second imaging pixel 3, and the first monitor element 2 shown in the present embodiment is merely an example, and is not limited thereto. .

  The first imaging pixel 1 will be described. In the present embodiment, as shown in FIG. 1, the horizontal alignment along the direction in which the gate wiring 32 extends is referred to as a row, and the vertical alignment along the signal wiring 30 is referred to as a column. One end of the electrodes of the photoelectric conversion element 15 of the first imaging pixel 1 and the second imaging pixel 3 and the photoelectric conversion element 17 of the first monitoring element 2 arranged in the same column is connected to a common bias wiring 33. It is connected. A constant bias voltage is applied to the electrodes from a bias power supply 53 via a bias wiring 33. The other ends of the electrodes of the photoelectric conversion elements 15 of the first imaging pixel 1 and the second imaging pixel 3 are connected to the TFT 16. The photoelectric conversion elements 15 arranged in the same column of each row are connected to a common signal wiring 30 arranged for each column via the source electrode and the drain electrode of the TFT 16. The gate electrodes of the TFTs 16 arranged in the first imaging pixel 1 and the second imaging pixel 3 in a predetermined row are connected to a common gate wiring 32 arranged in each row, and a gate driving circuit 52 is connected. Accordingly, ON / OFF of the TFT 16 is controlled for each row. The signal wiring 30 is connected to the imaging signal processing circuit 51.

  The monitoring photoelectric conversion element 17 of the first monitoring element 2 is a PIN type sensor. One electrode of the monitor photoelectric conversion element 17 is connected to the monitor signal processing circuit 55 via the first monitor wiring 31, and the other electrode is the same as that of the imaging photoelectric conversion element 15. One bias wiring 33 is connected to the bias power supply 53. When the radiation converted into visible light by the phosphor is incident on the monitoring photoelectric conversion element 17 provided in the first monitoring element 2, electrons and holes generated in the semiconductor layer are converted into the monitoring photoelectric conversion element 17. It is read by the electric field generated by the voltage applied to the electrodes at both ends. That is, electrons and holes are transported to each electrode of the monitoring photoelectric conversion element 17 by the potential difference applied to the electrodes at both ends of the monitoring photoelectric conversion element 17 from the bias power supply 53 and the monitoring signal processing circuit 55. By reading this charge with the monitor signal processing circuit 55, it is possible to detect the timing of radiation irradiation and to measure the radiation irradiation amount.

  According to the present embodiment, since the imaging signal cannot be obtained from the position where the monitor photoelectric conversion element 17 is arranged in the imaging region, the position of the first monitoring element 2 becomes a point defect. . Further, since the pixel in which the first monitor wiring 31 is arranged like the second imaging pixel 3 is different in shape from the first imaging pixel 1, it is different from the first imaging pixel 1. In this case, the level of the imaging signal and the SNR are different. Accordingly, regarding the point defect portion by the first monitor element 2 and the image pickup signal from the second image pickup pixel 3, it is necessary to correct the data by image processing. It can be handled with technology.

  Next, the configuration of the imaging pixel and the monitor element will be described. 2A, 2B, and 2C are plan views of the first imaging pixel 1, the first monitoring element 2, and the second imaging pixel 3, respectively, in FIG. 3A, 3B, and 3C are cross-sectional views corresponding to A-A ', B-B', and C-C ', respectively, in FIG.

  The first imaging pixel 1 in this embodiment includes an imaging photoelectric conversion element 15 and a TFT 16 that is a switch element that outputs an electrical signal corresponding to the electric charge of the photoelectric conversion element 15. The imaging photoelectric conversion element 15 is disposed on a TFT 16 provided on an insulating substrate such as a glass substrate, with the first interlayer insulating layer 110 interposed therebetween. The TFT 16 includes a control electrode 101, an insulating layer 102, a semiconductor layer 103, an impurity semiconductor layer 104 having an impurity concentration higher than that of the semiconductor layer 103, a first main electrode 105, Second main electrode 106. The impurity semiconductor layer 104 is in contact with the first main electrode 105 and the second main electrode 106 in a part of the region, and the first main electrode 105 and the second main electrode 106 in the region of the semiconductor layer 103 in contact with the part of the region. The region between the regions becomes the channel region of the TFT. The control electrode 101 is electrically joined to the gate wiring 32, the first main electrode 105 is electrically joined to the signal wiring 30, and the second main electrode 106 is the individual electrode 111 of the imaging photoelectric conversion element 15. And are electrically joined. In FIG. 2A, the individual electrode 111 is shown as the individual electrode 20.

  In the present embodiment, the first main electrode 105, the second main electrode 106, and the signal wiring 30 are integrally formed of the same conductive layer, and the first main electrode 105 constitutes a part of the signal wiring 30. ing. The insulating layer 107 is provided so as to cover the TFT, the gate wiring 32 and the signal wiring 30. In the present embodiment, an inverted stagger type TFT using a semiconductor layer mainly made of amorphous silicon and an impurity semiconductor layer is used as a switch element, but the present invention is not limited to this. For example, a staggered TFT mainly composed of polycrystalline silicon, an organic TFT, an oxide TFT, or the like can be used.

  The first interlayer insulating layer 110 is disposed between the substrate and a plurality of individual electrodes described later so as to cover the TFT, and has a contact hole 108. The individual electrode 111 of the imaging photoelectric conversion element 15 and the second main electrode 106 of the TFT are electrically joined through a contact formed in a contact hole 108 provided in the first interlayer insulating layer 110. The imaging photoelectric conversion element 15 includes an individual electrode 111, a third insulating layer 112, a second impurity semiconductor layer 113, and a second impurity layer on the first interlayer insulating layer 110 in this order from the first interlayer insulating layer 110 side. A semiconductor layer 114, a third impurity semiconductor layer 115, and a common electrode 116 are formed. The first bias wiring 33 disposed on the second interlayer insulating layer 120 is electrically connected to the common electrode 116 through the contact formed in the contact hole 122 provided in the second interlayer insulating film 120. Be joined. A fourth insulating layer 121 as a protective film is disposed on the first bias wiring 33.

  Next, the first monitoring element 2 will be described with reference to FIGS. 2B and 3B. Note that the same reference numerals are assigned to the same components as those of the first imaging pixel 1, and description thereof is omitted. The photoelectric conversion element 17 of the first monitoring element 2 is arranged on the first interlayer insulating layer 110 in order from the first interlayer insulating layer 110 side, the individual electrode 111, the third insulating layer 112, the second An impurity semiconductor layer 113 is included. Further, it is formed to include the second semiconductor layer 114, the third impurity semiconductor layer 115, and the common electrode 116. A first bias line 33 disposed on the second interlayer insulating layer 120 is electrically joined to the common electrode 116. In addition, the individual electrode 111 is connected to the first monitor wiring 31 through a contact formed in the contact hole 108 provided in the first interlayer insulating layer 110. When reading a signal from the photoelectric conversion element, the signal wiring 30 and the first monitoring wiring 31 are reset to different reference potentials by the imaging signal processing circuit 51 and the monitoring signal processing circuit 55, respectively.

  Next, the second imaging pixel 3 in which the first monitor wiring 31 and the imaging photoelectric conversion element 15 are arranged will be described with reference to FIGS. 2 (c) and 3 (c). The second imaging pixel 3 is different from the first imaging pixel 1 in that the first monitor wiring 31 is disposed under the insulating film 102, and the other configuration is the first imaging pixel. This is the same as the pixel 1 for use. The first monitor wiring 31 is arranged in parallel with the gate wiring 32, connected outside the pixel region, and connected to the monitor signal processing circuit 55.

  FIG. 4 is a circuit diagram of an input unit in the imaging signal processing circuit 51 to which a signal from the signal wiring 30 is input. The description of the subsequent stage of the imaging signal processing circuit 51 is omitted. The signal wiring 30 is connected to the inverting input terminal 10 of the operational amplifier 162. The inverting input terminal 10 of the operational amplifier 162 is connected to the output terminal 11 via the storage capacitor 164. A switch 163 is connected to the storage capacitor 164 in parallel. The non-inverting input terminal 12 is connected to the reference power source 176. The output terminal 11 is connected to a circuit subsequent to the imaging signal processing circuit 51. When reading an imaging signal from the imaging pixel, first, the switch 163 is short-circuited to reset the potential of the individual electrode of the photoelectric conversion element to the potential of the reference power source 176. At this time, the TFT 16 of the imaging pixel is also turned on. Ideally, the potential of the electrode to which the signal wiring 30 and the TFT 16 of the photoelectric conversion element 15 are connected is fixed to the reference power source 176 by the operation of the operational amplifier. After that, when the switch 163 is opened, the operational amplifier 162 integrates the current generated by the visible light by the photoelectric conversion element read from the signal wiring 30 by the storage capacitor 164 and outputs the imaging signal as a voltage signal. Similarly, the first monitor wiring 31 is also connected to a reference power supply having a voltage different from that of the reference power supply, and after being reset to a different voltage at the time of reading, a monitor signal is output. That is, in this embodiment, the power source for resetting the imaging photoelectric conversion element 15 and the monitor photoelectric conversion element 17 is the bias power source 53, the reference power source for the monitor signal processing circuit unit 55, and the imaging signal processing circuit. And 51 reference power supplies.

  Next, the operation of the radiation detection apparatus according to this embodiment will be described in detail. First, an ON voltage is sequentially applied to the TFTs of the first imaging pixel 1 and the second imaging pixel 3 to reset the individual electrode 111 of the imaging photoelectric conversion element 15 to the potential of the signal wiring 30. At this time, the switch 163 provided between the input and output of the operational amplifier 162 is reset by short-circuiting as described above. The monitor photoelectric conversion element 17 is directly connected to the first monitor wiring 31, and the individual electrode 111 of the monitor photoelectric conversion element 17 is connected by another reference power source connected to the first monitor wiring 31. Reset. Further, a bias having a constant voltage is applied from the bias power source 53 to the common electrode 116 of the photoelectric conversion element 15 for imaging and the photoelectric conversion element 17 for monitoring via the bias wiring 33. At this time, the imaging photoelectric conversion element 15 has an electric field strength determined by the potential difference between the potential of the bias power supply 53 and the potential of the individual electrode 111 reset by the reference power supply 176 and the film thickness of the second semiconductor layer 114. E1 is applied.

The monitoring photoelectric conversion element 17 is determined by the potential difference between the potential of the bias power supply 53 and the reset potential applied to the first monitoring wiring 31 and the film thickness of the second semiconductor layer 114. An electric field strength E2 is applied. The photoelectric conversion element 15 for imaging should have a large electric field strength E1 in order to increase the saturation dose. Moreover, the photoelectric conversion element 17 for monitoring may increase the dark current and increase the detection accuracy by increasing the electric field strength E2. For this reason, the electric field intensity E2 is preferably set to be small as long as the linearity of photoelectric conversion can be ensured with respect to radiation converted into visible light by a phosphor layer (not shown). Considering the above, for example, E1 and E2 having the following relationship are applied. Considering the potential of the bias power source 53, the potential of the signal wiring 30, the potential of the first monitoring wiring 31, the film thickness of the second semiconductor layer 114 of the photoelectric conversion element 15 for imaging and the photoelectric conversion element 17 for monitoring. It is good to decide.
E1 ≧ 40000V / cm
20000V / cm ≦ E2 ≦ 40000V / cm
E1 ≧ E2
In this state, when the radiation converted into visible light by the phosphor layer (not shown) enters the monitoring photoelectric conversion element 17, the visible light absorbed by the second semiconductor layer 114 is converted into electric charge. Electric charges are transported to the monitor signal processing circuit 55 through the first monitor wiring 31 by the electric field intensity E2. Therefore, automatic radiation detection and radiation dose measurement can be performed in real time. That is, when radiation is applied, a smaller potential difference is applied to the monitoring photoelectric conversion element 17 than to the imaging photoelectric conversion element 15.

  Thereafter, when the radiation dose measured by the measurement unit provided in the monitor signal processing circuit unit reaches a set value, a signal is sent to the radiation source to stop the radiation irradiation. Then, immediately after that, the ON voltage for selecting each row is sequentially applied from the gate drive circuit 52 to the TFT 16, thereby reading the charge accumulated in the imaging photoelectric conversion element 15 through the signal wiring 30. In the case of automatic radiation detection, the reset operation is repeatedly performed in the first monitoring element 2 during standby. Thereafter, when the charge is detected by the monitor signal processing circuit 55, the reset operation is stopped and the charge is accumulated during the radiation irradiation period. After a certain period of time or when the radiation dose reaches a set value, the ON voltage for selecting a row is sequentially applied from the gate drive circuit 52 to the TFT 16 of the imaging pixel, whereby the electric charge accumulated in the imaging photoelectric conversion element 15 is changed. Read through signal wiring.

(Embodiment 2)
Next, Embodiment 2 of the present invention will be described. FIG. 5 is an equivalent circuit diagram showing a circuit configuration of the radiation detection apparatus according to the present embodiment. Here, FIG. 5 shows an example in which pixels of 6 rows and 6 columns are provided, but the number is not limited to this, and, for example, 2000 × 2000 pixels may be provided. The difference from the first embodiment is that the first monitor wires 31 are arranged in parallel along the columns in parallel with the signal wires 30. In addition, an imaging pixel in which the photoelectric conversion element 15 for imaging and the photoelectric conversion element 17 for monitoring are arranged in one pixel is provided. Further, a connecting element for connecting the wiring is formed outside the outermost periphery of the pixel region, and the first monitoring wiring 31 in the form of a column is connected to the second monitoring wiring in a direction parallel to the gate wiring 32 inside the connecting element. This is a point drawn to 35.

  In the configuration of the first embodiment, as described above, the first monitoring element 2 provided with the monitoring photoelectric conversion element 17 becomes a point defect. If both the imaging photoelectric conversion element 15 and the monitor photoelectric conversion element 17 are arranged in one pixel as in this embodiment, automatic detection of radiation and real-time measurement of radiation dose are possible without causing point defects. It becomes. Further, the first monitor wiring 31 and the second monitor wiring are connected and output by the connecting element 5 provided outside the outermost row in the imaging region. By connecting the first monitoring wiring 31 to the second monitoring wiring 35 using the connection element 5, the connection of the monitoring wiring can be simplified as compared with the first embodiment, and no space is required. Even in such a configuration, by adjusting the voltages applied to the electrodes of the imaging photoelectric conversion element 15 and the monitoring photoelectric conversion element 17, the electric field strength applied to the second semiconductor layer 114 is E1 ≧ E2. It can be set in the relationship. Note that in the following description, descriptions of portions that overlap the contents of the first embodiment are omitted.

  In the present embodiment, the imaging photoelectric conversion element 15 is connected to the imaging signal processing circuit 51 via the TFT 16 and the signal wiring 30. The monitor photoelectric conversion element 17 for automatic radiation detection and radiation automatic exposure control is connected to the monitor signal processing circuit 55 via the first monitor wiring 31 and the second monitor wiring 35. . Specifically, the first imaging pixel 1 is provided with an imaging photoelectric conversion element 15 and a TFT 16 as in the pixel 1 of the first embodiment. The third imaging pixel 4 is provided with an imaging photoelectric conversion element 15 connected to the monitor photoelectric conversion element 17 and the TFT 16.

  A first monitor wiring 31 is routed around the fourth imaging pixel 6. Other configurations of the fourth imaging pixel 6 are the same as those of the first imaging pixel 1. In the present embodiment, the connection element 5 that connects the first monitor wiring 31 and the second monitor wiring 35 is formed outside the outermost row where the pixels in the imaging region are arranged. In the connection element 5, the first monitor wiring 31 routed in the direction parallel to the signal wiring 30 is switched to another wiring layer. The first monitor wiring 31 transferred to another wiring layer is routed to and connected to the second monitor wiring 35 that is orthogonal. Thus, the first monitor wirings 31 arranged in a plurality of columns can be collected. Note that the arrangement of pixels is merely an example, and is not limited to this.

  Next, the configuration of the pixels 4 and 6 and the connection element 5 will be described. FIGS. 6A, 6 </ b> B, and 6 </ b> C show the fourth image pickup pixel 4 including the image pickup and monitor photoelectric conversion elements, and the fourth line in which the first monitor wiring 31 is routed. The top view of the imaging element 6 and the connection element 5 arrange | positioned in the outermost periphery is shown. 7A, 7B, and 7C are cross-sectional views corresponding to A-A ', B-B', and C-C 'in FIG. 6, respectively. Since the first imaging pixel 1 is the same as the first imaging pixel 1 of the first embodiment, description thereof is omitted.

  First, the third imaging pixel 4 in the present embodiment will be described with reference to FIGS. 6 (a) and 7 (a). The third imaging pixel 4 includes an imaging photoelectric conversion element 15 and a monitoring photoelectric conversion element 17. In the plan view shown in FIG. 6A, the part of the individual electrode 20 is a part where the imaging photoelectric conversion element 15 is arranged, and the part of the individual electrode 21 is a part where the monitoring photoelectric conversion device 17 is arranged. .

  FIG. 7A is a cross section at a portion corresponding to the individual electrode 21 where the monitor photoelectric conversion device 17 of the third imaging pixel 4 is disposed. The individual electrode 21 shown in the plan view corresponds to the individual electrode 111 in the sectional view. The monitor photoelectric conversion element 17 is stacked on the first interlayer insulating layer 110 on an insulating substrate such as a glass substrate. The first interlayer insulating layer 110 is disposed between the substrate and the individual electrode 111 of the monitoring photoelectric conversion element 17. The individual electrode 111 of the monitoring photoelectric conversion element 17 and the first monitoring wiring 31 are electrically joined to each other through a contact formed in the contact hole 108 provided in the first interlayer insulating layer 110. The monitoring photoelectric conversion element 17 includes, on the first interlayer insulating layer 110, the individual electrode 111, the third insulating layer 112, the second impurity semiconductor layer 113, and the first impurity insulating layer 110 in order from the first interlayer insulating layer 110 side. 2 semiconductor layer 114, third impurity semiconductor layer 115, and common electrode 116. A first bias wiring 33 disposed on the second interlayer insulating layer 120 is electrically joined to the common electrode 116 via a contact. The first monitor wiring 31 is routed between the insulating layer 102 and the insulating layer 107.

  Next, the fourth imaging pixel 6 of the present embodiment will be described with reference to FIGS. 6B and 7B. The fourth imaging pixel 6 of the present embodiment includes an imaging photoelectric conversion element 15 and a TFT 16 having the same structure as that of the first imaging pixel 1. In the fourth imaging pixel 6, a first monitor wiring 31 is arranged in parallel with the first bias wiring 33 arranged in a column. The first monitor wiring 31 is formed so as to be sandwiched between the insulating film 102 and the insulating film 107.

  Next, the connection element 5 in the present embodiment will be described with reference to FIGS. 6C and 7C. The connection element 5 is disposed in the periphery of the image sensor and has a dummy photoelectric conversion element that does not output. The first monitor wiring 31 shown in FIG. 7A is routed along the pixels arranged in the column in parallel with the bias wiring 33 and arranged in the connection element 5. On the other hand, as shown in FIG. 6C, the connection element 5 is provided with a second monitor wiring 35. The first monitor wiring 31 and the second monitor wiring 35 are connected to the individual electrode 111 of the dummy photoelectric conversion element through contacts formed in the contact holes 108 and 109 of the first interlayer insulating layer 110. ing. That is, the first monitor wiring 31 and the second monitor wiring 35 are electrically connected. Therefore, in the connection element 5, the first monitor wiring 31 is connected to the second monitor wiring 35 that is orthogonal to each other. The connecting element 5 can be created together when creating a pixel.

(Embodiment 3)
Next, a third embodiment of the present invention will be described. FIG. 8 is an equivalent circuit diagram showing a circuit configuration of the radiation detection apparatus according to the present embodiment. Here, FIG. 8 shows an example in which pixels of 6 rows and 6 columns are provided, but the number is not limited to this, and, for example, 2000 × 2000 pixels may be provided. The difference from the first embodiment is that two systems of a first bias power supply 53 and a second bias power supply 54 are provided as bias power supplies. The first bias power supply 53 is connected to the imaging photoelectric conversion element 15, and the second bias power supply is connected to the monitoring photoelectric conversion element 17. As a result, the electric field intensity applied to the imaging photoelectric conversion element 15 and the electric field intensity applied to the monitoring photoelectric conversion element 17 can be individually set by the bias power source.

  Specifically, one electrode of the photoelectric conversion element 15 for imaging is connected to the imaging signal processing circuit 51 via the TFT 16 and the signal wiring 30. The other electrode is connected to the first bias power supply 53. One electrode of the photoelectric conversion element 17 for monitoring for automatic radiation detection and automatic radiation exposure control is connected to the monitoring signal processing circuit 55 via the first monitoring wiring 31, and the other electrode is connected to the second electrode. It is connected to the second bias power supply 54 via the bias wiring 34.

  The first imaging pixel 1 is provided with an imaging photoelectric conversion element 15 and a TFT 16 and has the same configuration as that of the first embodiment. The second monitoring element 7 provided with the monitoring photoelectric conversion element 17 is connected to the second bias wiring 34. In the second monitoring element 7, a first bias wiring 33, a second bias wiring 34, a first monitoring wiring 31, and a signal wiring 30 are wired. Note that the arrangement of pixels and monitoring elements is merely an example, and is not limited thereto.

  Next, the configuration of each element will be described. FIGS. 9A and 9B are plan views of the pixel 7 on which the photoelectric conversion element 17 for monitoring is arranged, the fifth imaging pixel 8 in which the monitor wiring and the bias wiring are routed, respectively. (A) and (b) are AA 'and BB' sectional drawing in FIG. 9, respectively.

  In the present embodiment, the second bias wiring 34 and the first monitoring wiring 31 are arranged so as to overlap in plan view with the interlayer insulating layer 110 interposed therebetween. The monitoring photoelectric conversion element 17 of the second monitoring element 7 is arranged on the first interlayer insulating layer 110 in order from the first interlayer insulating layer side, the individual electrode 111, the third insulating layer 112, the second The impurity semiconductor layer 113 is included. Further, the second semiconductor layer 114, the third impurity semiconductor layer 115, and the common electrode 116 are formed. A second bias wiring 34 is electrically connected to the common electrode 116. The individual electrode 111 is connected to the first monitor wiring 31 through a contact. The gate wiring 32 is formed between the first interlayer insulating layer 110 and the third interlayer insulating layer 123. The second bias wiring 34 and the first monitoring wiring 31 are arranged to face each other.

  The fifth imaging pixel 8 will be described. The fifth imaging pixel 8 is provided with a first monitor wiring 31 and a second bias wiring 34. The first monitor wiring 31 and the second bias wiring 34 are capacitively coupled to the gate wiring 32. The current flowing from the monitoring photoelectric conversion element 17 causes a voltage drop in the first monitoring wiring 31 and the second bias wiring 34. The voltage drop affects the potential of the gate wiring 32 that is capacitively coupled, causing crosstalk to a signal generated from the imaging photoelectric conversion element 15. Alternatively, there is a possibility that an induced current is generated when a current flows. In order to suppress this crosstalk (influence of changes in current and voltage), the first monitoring wiring 31 and the second bias wiring 34 are arranged so as to overlap in a plan view. Further, the voltage drop of the first monitor wiring 31 is designed to be equal to the voltage drop of the second bias wiring 34. Since the directions of the currents flowing through the first monitor wiring 31 and the second bias wiring 34 are opposite, the influence of the current / voltage change that occurs in the wiring cancels out, so that crosstalk is reduced. Further, the capacitance and distance that the first monitor wiring 31 and the second bias wiring each have between the gate wiring 32 are preferably taken into consideration for reducing crosstalk.

Changes in the current flowing through the first monitor wiring 31 and the second bias wiring 34 are the same. Therefore, the wiring resistance of the portion where the first monitoring wiring 31 and the second bias wiring 34 overlap, the wiring resistance of the first monitoring wiring 31 and the wiring resistance of the second bias wiring 34 are Rb. And Further, assuming that the coupling capacitance between the first monitoring wiring 31 and the gate wiring 32 is Ca and the coupling capacitance between the second bias wiring 34 and the gate wiring 32 is Cb,
Ra = Rb
Ca = Cb
If the wiring width, wiring layer film thickness, and film thickness of each insulating layer are set so as to satisfy the following, the influence of capacitive coupling or inductive coupling can be reduced.

  Further, in the present embodiment, the first monitor wiring 31 and the second bias wiring 34 are arranged so as not to overlap with the individual electrode 20 of the photoelectric conversion element. This is also a measure against crosstalk, and the first monitor wiring 31 and the second bias wiring 34 are arranged so as not to be coupled to the individual electrodes 20, so that the current flowing through the monitor photoelectric conversion element is reduced. To reduce the effects of Since the operation of the radiation detection apparatus according to the present embodiment and the setting of the electric field strength are the same as those in the first embodiment, they are omitted.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described. FIG. 11 is an equivalent circuit diagram showing a circuit configuration of the radiation detection apparatus according to the present embodiment, and FIG. 12 is a plan view of the third monitoring element 9 according to the present embodiment. The difference from the first embodiment is that the individual electrodes of the monitoring photoelectric conversion element 17 of the third monitoring element 9 are connected to the first monitoring wiring 31 via the TFT 36. Another difference is that a second gate drive circuit 56 for driving the gate of the TFT 36 is provided, and the gate of the TFT 36 and the second gate drive circuit are connected by a second gate wiring 37. Furthermore, the first monitoring wiring 31 is different from the signal wiring 30 in that it is formed of the same layer in the photoelectric conversion element.

  A signal from the individual electrode of the monitoring photoelectric conversion element 17 is connected to a first monitoring wiring 31 disposed in the same conductive layer as the signal line 30 through the contact and the TFT 36. 11 and 12, the gate of the TFT 36 of the third monitoring element 9 is connected to the second gate drive circuit 56 via the second gate wiring 37. In this embodiment, the monitor signal can be measured by intermittently turning on / off the TFT 36. The second gate drive circuit 56 can drive the gate of the TFT 36 for each row to control ON / OFF of the TFT 36. In addition, the gates of all the TFTs 36 can be driven at the same time, and monitor signals can be read from the third monitor element 9 at a time.

  When the monitor signal is intermittently read out by controlling the TFT 36, the monitor signal is read out after accumulating electric charge in the monitor photoelectric conversion element for a certain period of time. When it is detected that the sum of the integration values of the intermittently read signals exceeds a predetermined value, radiation irradiation is stopped, and the imaging signal is read from the imaging photoelectric conversion element 15. Also in this configuration, as in the above-described embodiment, the potential is applied to the monitor photoelectric conversion element and the imaging photoelectric conversion element by adjusting the potentials of the first bias power supply 53, the first monitor wiring 31, and the like. The electric field strength to be set can be set individually. Accordingly, if the relationship between the electric field intensity E2 applied to the monitor photoelectric conversion element and the electric field intensity E1 applied to the imaging photoelectric conversion element is set to E1 ≧ E2, a decrease in detection accuracy can be prevented. Is possible.

(Embodiment 5)
Next, a radiation imaging system using the detection apparatus of the present invention will be described with reference to FIG. X-rays 6060 generated by the X-ray tube 6050 serving as a radiation source pass through the chest 6062 of the patient or subject 6061 and enter the radiation imaging apparatus 6040. This incident X-ray includes information inside the body of the patient 6061. When X-rays enter, the radiation imaging apparatus 6040 converts them into electric charges, and electrical information is obtained. This information is converted into digital data, image-processed by an image processor 6070 as a signal processing means, and can be observed on a display 6080 as a display means in a control room.

  Further, this information can be transferred to a remote place by transmission processing means such as a telephone line 6090, and can be displayed on a display 6081 serving as a display means such as a doctor room in another place or stored in a recording means such as an optical disk. It is also possible for a doctor to make a diagnosis. Moreover, it can also record on the film 6110 used as a recording medium by the film processor 6100 used as a recording means.

1: first imaging pixel, 2: sensing element, 3: second imaging pixel, 15: imaging photoelectric conversion element, 16: TFT, 17: monitoring photoelectric conversion element, 30: signal line, 31 : First monitor wiring, 32: gate wiring, 33: first bias wiring, 51: imaging signal processing circuit, 52: gate drive circuit, 53: bias power supply, 55: monitoring signal processing circuit

Claims (6)

A plurality of first conversion elements having a first electrode and a second electrode for generating an imaging signal corresponding to the radiation, and a plurality of third electrodes and a fourth electrode for detecting the radiation A second conversion element;
And indicia pressurized between a first of the potential difference first the first electrode and the second electrode of the conversion element for which the first conversion element is reset, and smaller than the first potential difference a potential difference application means you applied between the third electrode and the fourth electrode of the second transducer a second potential difference for the second conversion element is reset,
A measurement unit for measuring the radiation dose based on a signal from the second conversion element;
I have a,
The potential difference applying means includes a first bias wiring connected to the first electrode of the first conversion element, and a second bias wiring connected to the third electrode of the second conversion element. ,
Wherein the fourth electrode has a first monitoring wires are connected, the radiation is characterized that you have been arranged so as to overlap the first monitoring wire and the second bias line in the plan view imaging apparatus. The potential difference application means includes first bias potential difference application means connected before Symbol first bias line and a second bias potential difference application means connected to said second bias line,
The radiation imaging apparatus according to claim 1, comprising: The radiation imaging apparatus according to claim 1 or 2, characterized in that it is connected through the switch from the first monitoring wire and the second transducer. Pixels including the first conversion element are arranged in a matrix,
The first monitor wiring is disposed along pixels arranged in a column;
A connecting element for connecting the first monitor wiring and the second monitor wiring arranged along the pixels arranged in a row is arranged outside the outermost peripheral pixel arranged in a matrix. The radiation imaging apparatus according to claim 1 , wherein the radiation imaging apparatus is provided. The potential difference applying means includes
The electric field strength applied between the first electrode and the second electrode of the first conversion element is E1, and the electric field strength applied to the third electrode and the fourth electrode of the second conversion element is E2. When
E1 ≧ 40000V / cm
20000V / cm ≦ E2 ≦ 40000V / cm
E1 ≧ E2
The first potential difference and the second potential difference are applied between the first electrode and the second electrode and between the third electrode and the fourth electrode. Item 5. The radiation imaging apparatus according to any one of Items 1 to 4 . A radiation source that generates radiation; and
The radiation imaging apparatus according to any one of claims 1 to 5 ,
A radiation imaging system comprising:

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