JP4357844B2 - Electromagnetic wave detector - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electromagnetic wave detector capable of detecting an image by radiation such as X-rays, electromagnetic waves such as visible light and infrared rays, and more particularly to an electromagnetic wave detector using an active matrix substrate as a read circuit board.
[0002]
[Prior art]
Conventionally, as a kind of electromagnetic wave detector, for example, a semiconductor film that generates an electric charge (electron-hole pair) by sensing an electromagnetic wave such as an X-ray, that is, a semiconductor film having electromagnetic wave conductivity (also called photoconductivity) The charge collecting electrodes for collecting the charges generated in the semiconductor film are arranged two-dimensionally in the row direction and the column direction, and a switching element is provided for each pixel, and the switching element is sequentially turned on for each row. There are known two-dimensional electromagnetic wave detectors that read out the charges for each column.
[0003]
The structure and principle of the two-dimensional electromagnetic wave detector are described in, for example, Non-Patent Document 1 below. The configuration and principle of the conventional electromagnetic wave detector described in Non-Patent Document 1 will be briefly described below.
[0004]
FIG. 9 is a cross-sectional view showing the detection principle of the electromagnetic wave detector. The electromagnetic wave detector includes, for example, a semiconductor film 101 exhibiting electromagnetic wave conductivity represented by a-Se, and a bias electrode 102 is formed on the upper layer of the semiconductor film 101 and a charge collecting electrode 103 is formed on the lower layer. The charge collection electrode 103 is connected to a storage capacitor (Cs) 104, and the storage capacitor 104 is connected to a charge detection amplifier 106 via a switching element 105 such as an FET (TFT).
[0005]
When electromagnetic waves such as X-rays enter such an electromagnetic wave detector, electric charges (electron-hole pairs) are generated in the semiconductor film 101. At this time, due to the bias voltage applied between the bias electrode 102 and the charge collection electrode 103, electrons generated in the semiconductor film 101 move to the + electrode side, and holes move to the − electrode side. The charge is stored in 104. The charge stored in the storage capacitor 104 is taken out by the charge detection amplifier 106 by turning on the switching element 105. In this way, the intensity of the electromagnetic wave incident on the semiconductor film 101 can be detected from the amount of charge detected by the charge detection amplifier 106.
[0006]
In addition, the components of such an electromagnetic wave detector (charge collecting electrode, storage capacitor, switching element) are arranged in a two-dimensional matrix, and the electric charges are read out in a line-sequential manner, so that the two-dimensional electromagnetic waves to be detected are detected. Information can be obtained. Here, as the two-dimensional matrix array, an active matrix array using thin film transistors (TFTs) as switching elements can be used.
[0007]
FIG. 10A shows the switching element 105, the storage capacitor 104, the charge collection electrode 103, and the wiring (scanning line (gate wiring) 107, signal line (source wiring) 108) for driving them: FIG. ))), A semiconductor film 101 provided on the active matrix array 110, and a bias electrode 102 provided thereon, and a cross-sectional structure (for one pixel) of the electromagnetic wave detector. Is. FIG. 10B is a plan view of the active matrix array shown in FIG. 10A as viewed from above, and shows a layout per pixel.
[0008]
By the way, in the above-described electromagnetic wave detector, the charge collection electrode 103 plays a role of collecting charges generated in the semiconductor film 101 thereon, but charges are easily trapped in the gap between the adjacent charge collection electrodes 103. It has been known.
[0009]
Here, the gap between the charge collection electrodes refers to an arrow portion in the schematic diagram shown in FIG. The mechanism of charge trap generation is described in Non-Patent Document 2, for example. It is considered that this charge trap is likely to occur at the interface between the active matrix substrate 110 and the semiconductor film 101 and at a portion in the semiconductor film 101 close to the interface. If the charge is excessively trapped between the charge collection electrodes 103, an adverse effect such as an afterimage or a decrease in sensitivity occurs when an image is captured.
[0010]
For such a trap charge, for example, Patent Document 1 discloses a method of eliminating the trap charge by irradiating light to a region of the semiconductor film 101 that generates the trap charge. For this reason, for example, as shown in FIG. 12, a light source 109 is installed on the back surface of the active matrix substrate 110, and the semiconductor film 101 is irradiated with light through the active matrix substrate 110, thereby reducing the trap charges described above. Can do.
[0011]
[Non-Patent Document 1]
SO Kasap, JA Rowlands, “Direct-Conversion Flat-Panel X-Ray Image Sensors for Digital Radiography”, Proceedings of the IEEE, USA, April, 2002, Vol. 90, No. 4, pp.591-604
[0012]
[Non-Patent Document 2]
W. Zhao, G. DeCrescenzo, JA Rowlands, "Investigation of lag and ghosting in amorphous selenium flat-panel x-ray detectors", Proceedings of SPIE, USA, May, 2002, Vol. 4682, pp. 9-20 "
[0013]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-9153 (publication date: January 10, 1997)
[0014]
[Problems to be solved by the invention]
In the conventional configuration, as shown in FIG. 11, the signal line 108 and the scanning line 107 formed of a metal film exist between the adjacent charge collection electrodes 103. In the electromagnetic wave detector, as described above, the scanning line and the signal line and the charge collecting electrode are not designed to overlap each other in plan view because the time constant (wiring resistance value × wiring capacitance) of each wiring is determined. ) Is made as small as possible, and is a useful configuration for obtaining the ability to transmit an electrical signal with high frequency and high accuracy.
[0015]
However, in a configuration in which a wiring formed of a metal film is present between adjacent charge collecting electrodes 103, a method of eliminating light trapping by irradiating the semiconductor film 101 with light from the back surface of the active matrix substrate 110 is employed. The following problems occur. In other words, in the region where these wirings are arranged, the irradiation light is blocked by the wirings, so that the region where the charges are trapped cannot be efficiently irradiated, and the generation of charge traps is sufficiently suppressed. There is a problem that can not be.
[0016]
Of course, a method of reducing the area shielded by the wiring by narrowing the line width of the signal line 108 or the scanning line 107 is also conceivable. However, these wirings suppress the delay of the electric signal flowing therethrough, and S / Since it is necessary to detect an image signal excellent in N, reduction of wiring resistance is required, and there is a limit to narrowing the line width.
[0017]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an active matrix having a device structure capable of eliminating trapped charges by efficiently irradiating light between gaps of charge collecting electrodes. It is to provide a substrate and an electromagnetic wave detector.
[0018]
[Means for Solving the Problems]
In order to solve the above problems, an active matrix substrate of the present invention has an active matrix substrate in which signal lines and scanning lines are arranged in a lattice shape on the substrate, and a switching element and a pixel electrode are formed for each unit lattice. 1 is characterized in that an opening is formed in the signal line and / or the scanning line.
[0019]
In the electromagnetic wave detector using the active matrix substrate, a semiconductor film and a bias electrode are formed on the active matrix substrate. In such an electromagnetic wave detector, the pixel electrode in the active matrix substrate plays a role of collecting charges generated in the semiconductor film thereon, but the charge is easily trapped in the gap between adjacent pixel electrodes.
[0020]
In the electromagnetic wave detector using the active matrix substrate, in order to eliminate the generation of trap charges, a light source is installed on the back surface of the active matrix substrate, and the semiconductor film is irradiated with light through the active matrix substrate. It is assumed that a configuration is taken.
[0021]
Under such a premise, according to the above configuration, the light emitted from the light source passes through the openings provided in the wiring of the signal lines and the scanning lines. Then, the light can be caused to wrap around the wiring on the side opposite to the light irradiation side by the diffraction of the light passing through the opening.
[0022]
This makes it possible to irradiate light efficiently to the semiconductor film on the back side of the wiring and increase the wiring resistance even when the substantial wiring width is the same as in the conventional configuration in which the wiring has no opening. Therefore, the light can be efficiently irradiated to the place where the charge is trapped.
[0023]
In the active matrix substrate, the opening may be a slit provided along the extending direction of the signal line and / or the scanning line.
[0024]
According to said structure, light can be efficiently irradiated to the gap | interval of the pixel electrodes formed in the grid | lattice form.
[0025]
In the active matrix substrate, the signal line and / or the scanning line may be formed so that the line width is narrowed at the intersection of the signal line and the scanning line.
[0026]
According to the above configuration, the area of the intersection between the signal line and the scanning line is reduced, and the wiring capacitance between the signal line and the scanning line (mainly parasitic capacitance generated at the intersection) can be reduced. Thereby, the time constant of wiring can be made small and the electromagnetic wave detector excellent in S / N is realizable.
[0027]
In the active matrix substrate, an interlayer insulating film may be interposed between the signal line and / or scanning line and the pixel electrode.
[0028]
According to the above configuration, the light emitted from the light source passes through the opening inside the wiring and then passes through the interlayer insulating film, so that the light wraps around the back side of the signal line or the scanning line by diffraction. It brings about the effect of becoming easy. Thereby, it is possible to irradiate light more efficiently on the place where the electric charge is trapped.
[0029]
In order to solve the above problems, the electromagnetic wave detector of the present invention includes the active matrix substrate, a semiconductor film formed on the upper surface of the active matrix substrate, and a bias electrode formed on the upper surface of the semiconductor film. The light source capable of irradiating the active matrix substrate is provided on the surface of the active matrix substrate opposite to the surface on which the semiconductor film is formed.
[0030]
According to the above configuration, the semiconductor film on the back side of the wiring can be efficiently irradiated with light even when the substantial wiring width is the same as in the conventional configuration in which the active matrix substrate has no opening in the wiring. Therefore, it is possible to efficiently irradiate light where the charges are trapped without increasing the wiring resistance.
[0031]
The electromagnetic wave detector may include a diffusing unit that converts irradiation light from the light source into diffused light between the active matrix substrate and the light source.
[0032]
According to the above configuration, the light emitted from the light source is diffused by the diffusing unit before being incident on the active matrix substrate, and incident light in an oblique direction is generated. This brings about an effect that light easily goes around the signal line and the scanning line, and light can be more efficiently irradiated to the place where charges are trapped in the semiconductor film.
[0033]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS. 1 to 8 as follows. In the following description, a plurality of electromagnetic wave detection elements corresponding to one pixel of an image to be detected are provided, and an electromagnetic wave detector is a two-dimensional array.
[0034]
FIG. 1A is a sectional view showing the structure of one pixel unit of the electromagnetic wave detector, and FIG. 1B is a plan view thereof. The size of one pixel shown in FIGS. 1A and 1B is about 0.1 mm × 0.1 mm to 0.3 mm × 0.3 mm, and this pixel (electromagnetic wave detector) is the whole electromagnetic wave detector. Generally, an array of about 500 × 500 to 3000 × 3000 pixels is arranged in an XY matrix. Assuming X-ray chest imaging, a size of about 17 "x 17" is required.
[0035]
As shown in FIGS. 1A and 1B, the electromagnetic wave detector includes an active matrix substrate 1, a semiconductor film 2 having electromagnetic wave conductivity, and a bias electrode (common electrode) connected to a power source (not shown). 3 are sequentially formed. The semiconductor film 2 generates charges (electrons-holes) inside when irradiated with electromagnetic waves such as X-rays. That is, the semiconductor film 2 has electromagnetic wave conductivity, and is for converting electromagnetic wave image information such as X-rays into charge information.
[0036]
The semiconductor film 2 is made of, for example, amorphous a-Se (amorphous selenium) containing selenium as a main component (having a content of 50% or more). In addition, CdTe, CdZnTe, PbI ₂ , HgI ₂ , GaAs, Si, or the like can also be used as the semiconductor film 2.
[0037]
Hereinafter, the active matrix substrate 1 will be described in detail. The active matrix substrate 1 includes a glass substrate 11, a scanning line (gate electrode) 12, a storage capacitor line (storage capacitor electrode) 13, a gate insulating film 14, a connection electrode 15, a channel layer 16, a contact layer 17, a signal line (source electrode). ) 18, an insulating protective film 19, an interlayer insulating film 20, and a pixel electrode (charge collecting electrode) 21. In the active matrix substrate 1, signal lines 18 and scanning lines 12 are arranged in a grid pattern on a glass substrate 11, and a TFT (Thin Film Transistor) 4 that is a switching element and a pixel electrode 21 are formed for each unit grid. ing.
[0038]
Further, in the active matrix substrate 1, the TFT 4 is configured by the scanning line 12, the gate insulating film 14, the signal line 18, the connection electrode 15, the channel layer 16, the contact layer 17, and the like. A storage capacitor (Cs) 5 is constituted by the film 14, the connection electrode 15, and the like.
[0039]
Here, as shown in FIGS. 2A to 2C, a portion of the scanning line 12 constituting the TFT 4 is a gate electrode 12a, and a portion of the signal line 18 constituting the TFT 4 is a source electrode 18a. A portion of the capacitor line 13 constituting the storage capacitor 5 is referred to as a storage capacitor electrode 13a.
[0040]
The first embodiment exemplifies a configuration in which the gate electrode 12a, the source electrode 18a, and the storage capacitor electrode 13a are configured to share part of the scanning line 12, the signal line 18, and the storage capacitor line 13, respectively. However, the gate electrode 12a, the source electrode 18a, and the storage capacitor electrode 13a may be configured separately from the scanning line 12, the signal line 18, and the storage capacitor line 13, respectively.
[0041]
The glass substrate 11 is a support substrate. As the glass substrate 11, for example, an alkali-free glass substrate (for example, # 1737 manufactured by Corning) can be used. The scanning lines 12 and the signal lines 18 are electric wirings (metal wirings) arranged in a lattice pattern, and TFTs 4 are formed at the respective intersections.
[0042]
The TFT 4 is a switching element, and each of its source and drain is connected to the signal line 18 and the connection electrode 15. That is, the signal line 18 includes a straight line portion as a signal line and an extended portion (that is, the source electrode 18a) for constituting the TFT 4, and the connection electrode 15 constitutes the TFT 4 while constituting the drain electrode of the TFT 4. And the storage capacitor 5 are provided.
[0043]
The gate insulating film 14 includes SiN _x And SiO _x Etc. can be used. The gate insulating film 14 is provided so as to cover the gate electrode 12a and the storage capacitor electrode 13a, and a part located on the gate electrode 12a acts as a gate insulating film in the TFT 4 and a part located on the storage capacitor electrode 13a. Acts as a dielectric layer in the storage capacitor 5. That is, the storage capacitor 5 is formed by the overlapping region of the storage capacitor electrode 13 a and the connection electrode 15 formed in the same layer as the gate electrode 2. As the gate insulating film 14, SiN _x And SiO _x In addition, an anodic oxide film obtained by anodizing the gate electrode 14a and the storage capacitor electrode 13a can be used in combination.
[0044]
The channel layer (i layer) 16 is a channel portion of the TFT 4 and serves as a current path connecting the source electrode 18 a and the connection electrode 15. Contact layer (n ⁺ (Layer) 17 serves as a contact between the channel layer 16 and the source electrode 18 a and a contact between the channel layer 16 and the connection electrode 15.
[0045]
The insulating protective film 19 is formed over substantially the entire surface (substantially the entire region) on the signal line 18 and the connection electrode 15, that is, on the glass substrate 11. Thus, the connection electrode 15 and the source electrode 18a are protected, and the electrodes are electrically insulated and separated. In addition, the insulating protective film 19 has a contact hole 22 at a predetermined position, that is, a portion located on a portion of the connection electrode 15 facing the storage capacitor electrode 13 a via the storage capacitor 5.
[0046]
An interlayer insulating film 20 is provided above the insulating protective film 19. The interlayer insulating film 20 is made of a translucent resin having a thickness of 1 to 5 μm, and the TFT 4 is planarized. A pixel electrode 21 made of a conductive film such as ITO or Al is provided on the upper layer of the interlayer insulating film 20, that is, the uppermost layer of the active matrix substrate 1. Also in the interlayer insulating film 20, the contact hole 22 penetrates the same place as the insulating protective film 19, and the pixel electrode 21 is connected to the connection electrode 15 through the contact hole 22.
[0047]
Further, the semiconductor film 2 and the bias electrode 3 are formed on the pixel electrode 21 so as to cover substantially the entire surface of the active matrix substrate 1. In some cases, a charge blocking layer or a buffer layer may be provided in the upper layer and / or lower layer of the semiconductor film 2, but in the electromagnetic wave detector according to the first embodiment, these layers are defined as the semiconductor film 2. . Examples of charge blocking layers and buffer layers include Se layers containing As and Te, Se layers doped with a small amount of halogen, alkali metal, etc., or Sb ₂ S _Three , CeO ₂ And high resistance semiconductor layers such as CdS.
[0048]
A power supply (not shown) is connected between the bias electrode 3 and the storage capacitor electrode 13 a so that a voltage can be applied to the semiconductor film 2. As a result, an electric field can be generated between the bias electrode 3 and the pixel electrode 21 via the storage capacitor 5. At this time, since the semiconductor film 2 and the storage capacitor 5 are electrically connected in series, the semiconductor film is absorbed by electromagnetic waves such as X-rays while a bias voltage is applied to the bias electrode 3. When charges (electron-hole pairs) are generated in 2, the generated electrons move to the + electrode side and the holes move to the-electrode side. As a result, charges are accumulated in the storage capacitor 5.
[0049]
In the entire electromagnetic wave detector, a plurality of pixel electrodes 21 are arranged one-dimensionally or two-dimensionally, and the electromagnetic wave detectors are individually connected to the storage capacitor 5 and the storage capacitor 5 individually connected to the pixel electrode 21. A plurality of TFTs 4 are provided. Thus, one-dimensional or two-dimensional electromagnetic wave information is temporarily stored in the storage capacitor 5 and the TFT 4 is sequentially scanned, whereby the one-dimensional or two-dimensional charge information can be easily read out. In order to read out the charge information, a charge detection amplifier is connected to the end of each signal line 18 (see FIG. 9).
[0050]
The basic structure of the electromagnetic wave detector according to the present embodiment has been described above. Next, the characteristic points of the electromagnetic wave detector will be described.
[0051]
The electromagnetic wave detector according to the present embodiment is particularly characterized by the shapes of the signal line 18 and the scanning line 12. For example, as shown in FIG. 1B, the signal line 18 used in the electromagnetic wave detector is provided with an opening 181 along the extending direction of the wiring at a substantially central portion of the wiring. For example, an opening 181 having a width of 3 μm is provided in a slit shape for a signal line having a line width of 13 μm. The opening 181 is formed at the same time when the signal line 18 is patterned, and light can be transmitted therethrough.
[0052]
Further, the electromagnetic wave detector is a planar light source composed of a light source (for example, an LED (Light Emitting Diode)) on the back side of the active matrix substrate 1 (that is, the side opposite to the formation side of the pixel electrode 21 with respect to the active matrix substrate 1). ). As described in the description of the prior art, this is because the trap charge generated in the semiconductor film 2 between the pixel electrodes 21 by irradiating light from the back surface side of the active matrix substrate 1 and applying the light to the semiconductor film 2. This is to stabilize the characteristics of the electromagnetic wave detector (to suppress problems such as Lag (afterimage) and sensitivity reduction).
[0053]
Here, in the conventional configuration, when light is irradiated to the gap between the pixel electrodes, the light is blocked by the wiring disposed between the pixel electrodes, and the semiconductor film in the gap cannot be efficiently irradiated with light. there were. On the other hand, in the configuration of the electromagnetic wave detector according to the present embodiment, as shown in FIG. 1B, the signal line 18 is provided with the slit-shaped opening 181, so that the semiconductor on the signal line 18 is provided. The charge trapping region in the film 2 can be efficiently irradiated with light. Therefore, in the electromagnetic wave detector of the present application, it is possible to suppress problems such as Lag (afterimage) and sensitivity reduction to a level where there is no practical problem.
[0054]
The active matrix substrate 1 has a configuration in which a light-transmitting interlayer insulating film 20 is interposed between the signal line 18 and the semiconductor film 2. Here, the interlayer insulating film 20 is assumed to have a thickness of 1 to 5 μm. With this configuration, there is also an effect that the light irradiated from the back surface of the active matrix substrate 1 is likely to easily sneak into the upper portion of the signal line 18 due to light diffraction when passing through the interlayer insulating film 20. For this reason, it can be said that the electromagnetic wave detector according to the present embodiment preferably has a configuration in which the interlayer insulating film 20 is provided between the signal line 18 and the semiconductor film 2.
[0055]
However, even if the interlayer insulating film 20 is not provided and the signal line 18 and the semiconductor film 2 are close to each other only through the protective insulating film 19, the light incident on the semiconductor film 2 is diffracted inside thereof. . Further, it is considered that trapped charges generated in the semiconductor film 2 are generated not only at the interface between the active matrix substrate 1 and the semiconductor film 2 but also at a portion close to the interface in the semiconductor film 2. Therefore, the present invention does not deny application to the active matrix substrate 1 that does not include the interlayer insulating film 20.
[0056]
Further, the thickness of the interlayer insulating film 20 is not useful when the thickness is less than 1 μm because the light diffraction effect is abruptly deteriorated. When the thickness is greater than 5 μm, it is difficult to control the thickness (uniformity). Alternatively, it is not preferable because a process problem such as formation of a contact hole becomes difficult.
[0057]
Further, as shown in FIG. 3A, the light diffraction effect due to the intervening interlayer insulating film brings about a corresponding effect even in the conventional configuration in which no opening is formed in the wiring. However, in the electromagnetic wave detector according to the present embodiment, by providing the opening 181 in the signal line 18, as shown in FIG. 3B, the irradiation region of the light to the semiconductor film 2 by the diffracted light is expanded. As a result, light can be efficiently applied to the gaps between the pixel electrodes 21 without reducing the substantial wiring width (that is, without increasing the wiring resistance).
[0058]
In the above description, the configuration in the case where the opening 181 is provided in the signal line 18 is illustrated. However, the same effect as that of the signal line 18 can be obtained by providing an opening in the scanning line 12 as well. FIG. 4 shows an example in which the opening 121 is provided in the scanning line 12 in addition to the signal line 18. This makes it possible to eliminate the charge traps between the pixels in the vertical direction and the horizontal direction.
[0059]
The electromagnetic wave detector may have a structure in which an opening is provided only in one of the signal line 18 and the scanning line 12. However, when the line widths of the scanning line 12 and the signal line 18 are greatly different, it is preferable to preferentially provide an opening in a wiring having a thick line width.
[0060]
When the signal line 18 and the scanning line 12 are formed not only from a metal film but also from a laminated film of a metal film and a transparent conductive film (for example, a laminated film of Ta and ITO), Both may be provided with openings, or the openings may be provided only on the metal film. Further, in each of the above examples, a drawing is shown in which no opening is provided at the intersection between the signal line 18 and the scanning line 12, but an opening may be provided at the intersection.
[0061]
Further, in the active matrix substrate having the structure in which the opening is provided in the wiring as described above, the following modifications can be taken.
[0062]
In FIG. 5, a slit-like opening 181 is provided in the signal line 18, and the line width of the signal line 18 is narrowed at the intersection of the signal line 18 and the scanning line 12. Thereby, the area of the intersection between the signal line 18 and the scanning line 12 is reduced, and the wiring capacitance between the signal line 18 and the scanning line 12 (mainly parasitic capacitance generated at the intersection) can be reduced. . Thereby, the time constant of the wiring can be reduced, and an electromagnetic wave detector having an excellent S / N can be realized. The noise gain of the signal read from the signal line 18 is expressed by Cd / Cf (Cd: wiring capacity of the signal line, Cf: feedback capacity of the charge detection amplifier). It directly affects the signal S / N.
[0063]
FIG. 6 shows a configuration in which, in addition to the configuration of FIG. 5, the scanning line 12 is also provided with a slit-like opening 121 and the line width of the scanning line 12 is narrowed at the intersection of the signal line 18 and the scanning line 12. Indicates. This eliminates the charge trap between pixels in the vertical direction and the horizontal direction, reduces the area of the intersection of the signal line 18 and the scanning line 12, and reduces the wiring capacity of the signal line 18 and the scanning line 12. Can do.
[0064]
Further, FIG. 7 shows an example in which the openings formed in the signal lines 18 and the scanning lines 12 in the configuration of FIG. 6 are composed of a plurality of openings. As described above, the size, shape, arrangement interval, and the like of the opening are not particularly limited as long as the light irradiation efficiency with respect to the semiconductor film in the region on the wiring is improved.
[0065]
In addition, in the electromagnetic wave detector according to the present embodiment, light is efficiently circulated to the opposite side to the light irradiation side with respect to the wiring by using light diffraction, and the light irradiation efficiency to the semiconductor film 2 is improved. It is improving. In order to further improve the light wraparound effect, as shown in FIG. 8, a configuration in which a diffusion plate 7 is provided between the active matrix substrate 1 and the light source 6 installed behind the active matrix substrate 1 can be adopted.
[0066]
As described above, by disposing the diffusing plate 7, the light incident on the active matrix substrate 1 is obliquely incident on the normal direction of the substrate. And by the synergistic effect of the increase in the light incident in the oblique direction and the light diffraction, the light can be efficiently circulated to the side opposite to the light irradiation side with respect to the wiring. In addition, the in-plane distribution of the light intensity can be made uniform by using diffused light as the light applied to the active matrix substrate 1. In the configuration shown in FIG. 8, the diffusion plate 7 and the light source 6 may be integrally formed.
[0067]
【The invention's effect】
As described above, the active matrix substrate of the present invention has a configuration in which openings are formed in the signal lines and / or scanning lines.
[0068]
Therefore, in the electromagnetic wave detector using the active matrix substrate, the light emitted from the light source is not provided in the signal line or the scanning line wiring on the assumption that the light source is installed on the back surface of the active matrix substrate. Pass through the department. The diffraction of the light passing through the opening allows the light to circulate to the side opposite to the light irradiation side with respect to the wiring, and the efficiency is improved in a place where charges are trapped without increasing the wiring resistance. There is an effect that light can be irradiated well.
[0069]
In the active matrix substrate, the opening may be a slit provided along the extending direction of the signal line and / or the scanning line.
[0070]
Therefore, there is an effect that light can be efficiently irradiated to the gap between the pixel electrodes formed in a lattice shape.
[0071]
In the active matrix substrate, the signal line and / or the scanning line may be formed so that the line width is narrowed at the intersection of the signal line and the scanning line.
[0072]
Therefore, the area of the intersection between the signal line and the scanning line is reduced, the wiring capacitance between the signal line and the scanning line (mainly parasitic capacitance generated at the intersection) can be reduced, and the S / N is excellent. An effect is obtained that an electromagnetic wave detector can be realized.
[0073]
In the active matrix substrate, an interlayer insulating film may be interposed between the signal line and / or scanning line and the pixel electrode.
[0074]
Therefore, after the light emitted from the light source passes through the opening in the wiring and then passes through the interlayer insulating film, the light easily wraps around to the back side of the signal line or the scanning line due to diffraction, and the charge There is an effect that it is possible to irradiate light more efficiently to the place where is trapped.
[0075]
As described above, the electromagnetic wave detector of the present invention includes the active matrix substrate, a semiconductor film formed on the upper surface of the active matrix substrate, and a bias electrode formed on the upper surface of the semiconductor film. The light source capable of irradiating the active matrix substrate is provided on the surface of the active matrix substrate opposite to the surface on which the semiconductor film is formed.
[0076]
Therefore, compared with the conventional configuration in which the active matrix substrate does not have an opening in the wiring, even if the substantial wiring width is the same, the semiconductor film on the back side of the wiring can be efficiently irradiated with light. There is an effect that light can be efficiently irradiated to a place where charges are trapped without increasing the resistance.
[0077]
The electromagnetic wave detector may include a diffusing unit that converts irradiation light from the light source into diffused light between the active matrix substrate and the light source.
[0078]
Therefore, the light emitted from the light source is diffused by the diffusing means before being incident on the active matrix substrate, and incident light in an oblique direction is generated. This makes it easier for light to wrap around the signal lines and the scanning lines, and has the effect of irradiating light more efficiently on the semiconductor film where charges are trapped.
[Brief description of the drawings]
1A and 1B show an embodiment of the present invention, in which FIG. 1A is a cross-sectional view showing a structure of a pixel unit of an electromagnetic wave detector, and FIG. 1B is a plan view thereof.
2A is a plan view showing the shape of a scanning line and a gate electrode, FIG. 2B is a plan view showing the shape of a signal line and a source electrode, and FIG. 2C is a charge capacity. It is a top view which shows the shape of a line | wire and a charge capacity electrode.
FIG. 3 (a) is a diagram showing a light irradiation region to a semiconductor film in the structure of a conventional active matrix substrate, and FIG. 3 (b) is a diagram illustrating the semiconductor film in the structure of the active matrix substrate of the present invention. It is a figure which shows a light irradiation area | region.
FIG. 4, showing another embodiment of the present invention, is a plan view showing the structure of one pixel unit of an electromagnetic wave detector.
FIG. 5, showing still another embodiment of the present invention, is a plan view showing a structure of one pixel unit of an electromagnetic wave detector.
FIG. 6 is a plan view showing a structure of one pixel unit of an electromagnetic wave detector according to still another embodiment of the present invention.
FIG. 7, showing still another embodiment of the present invention, is a plan view showing the structure of one pixel unit of an electromagnetic wave detector.
FIG. 8, showing still another embodiment of the present invention, is a sectional view showing the structure of an electromagnetic wave detector in which a diffusion plate is provided between a light source and an active matrix substrate.
FIG. 9 is a diagram illustrating a detection principle of an electromagnetic wave detector.
10A and 10B show a conventional electromagnetic wave detector, in which FIG. 10A is a cross-sectional view showing the structure of a unit of one pixel of the electromagnetic wave detector, and FIG. 10B is a plan view thereof.
FIG. 11 is a plan view showing a gap between adjacent pixel collecting electrodes in the electromagnetic wave detector.
FIG. 12 is a cross-sectional view showing a configuration when a light source is disposed on the back surface of an active matrix substrate in a conventional electromagnetic wave detector.
[Explanation of symbols]
1 Active matrix substrate
2 Semiconductor film
3 Bias electrode
4 TFT (switching element)
5 storage capacity
6 Light source
7 Diffusion plate (Diffusion means)
11 Glass substrate (substrate)
12 scanning lines
18 signal lines
20 Interlayer insulation film
21 Pixel electrode
121 ・ 181 opening

Claims (5)

On a substrate, signal lines, the scanning lines are arranged in a grid, an active matrix switching element and a pixel electrode are formed for each unit cell,
A semiconductor film formed on the upper surface of the active matrix substrate;
In the electromagnetic wave detector comprising a bias electrode formed on the upper surface of the semiconductor film ,
An opening is formed in a region where the signal line and / or the scanning line of the scanning line does not overlap the scanning line ,
An electromagnetic wave detector comprising: a light source capable of irradiating the active matrix substrate on a surface opposite to the surface on which the semiconductor film is formed of the active matrix substrate. The electromagnetic wave detector according to claim 1, wherein the opening is a slit provided along the extending direction of the signal line and / or the scanning line. 2. The electromagnetic wave detector according to claim 1, wherein the signal line and / or the scanning line is formed to have a narrow line width at an intersection between the signal line and the scanning line. 2. The electromagnetic wave detector according to claim 1, wherein an interlayer insulating film is interposed between the signal line and / or scanning line and the pixel electrode.   The electromagnetic wave detector according to claim 1, further comprising a diffusing unit that converts irradiation light from the light source into diffused light between the active matrix substrate and the light source.

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