JP2009212120A - Electromagnetic wave detection element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave detection element inhibiting generation of leakage current from a thin film transistor while inhibiting an increase in parasitic capacitance of the signal line. <P>SOLUTION: A lower electrode 14 formed of a conductive member with light blocking effects against electromagnetic waves for collecting electric charge generated in a semiconductor layer 6 is extended to form a light resistant area on an electromagnetic wave irradiation surface on a part containing a connection with a TFT switch 4 of the signal line 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave detection element, and in particular, a TFT active matrix in which a sensor unit is provided corresponding to each intersection of a plurality of scanning wirings and a plurality of signal wirings arranged to cross each other, and detects an image. The present invention relates to an electromagnetic wave detection element using a substrate.

  In recent years, an X-ray sensitive layer is disposed on an active matrix substrate in which thin film transistors (TFTs) are provided in a matrix, and radiation such as an FPD (flat panel detector) that can directly convert X-ray information into digital data. An image detection apparatus has been put into practical use. Compared with conventional imaging plates, this FPD has the advantage that images can be confirmed instantly and moving images can be confirmed, and is rapidly spreading.

  Various types of radiological image detection apparatuses of this type have been proposed. For example, a direct conversion system that directly converts radiation into electric charges and stores the radiation, CsI: Tl, GOS (Gd2O2S: Tb) There is an indirect conversion method in which the light is converted into light by a scintillator, etc., and the converted light is converted into electric charges in a semiconductor layer and accumulated (for example, Patent Document 1 by the present applicant).

  As an example, FIG. 8 shows a plan view showing the structure of one pixel unit of the electromagnetic wave detection element 10 ′ used in the indirect conversion type radiation image detection apparatus, and FIG. A cross-sectional view along line A is shown.

  As shown in FIG. 8, the electromagnetic wave detecting element 10 ′ includes a sensor unit 103 ′ and a TFT switch corresponding to the intersecting portions of the plurality of scanning wirings 101 ′ and the plurality of signal wirings 3 ′ arranged to intersect each other. 4 'is provided.

  As shown in FIG. 9, the sensor unit 103 ′ has a light transmission property on the side of the semiconductor layer 6 ′ where the charge is generated when irradiated with light and the irradiation surface side where the light of the semiconductor layer 6 ′ is irradiated. An upper electrode 7 ′ for applying a bias voltage to the semiconductor layer 6 ′ and a non-irradiated surface side of the semiconductor layer 6 ′ formed by a conductive member, and a charge generated in the semiconductor layer 6 ′. The lower electrode 14 'for collecting

  Further, in the electromagnetic wave detecting element 10 ′, a common electrode wiring 25 ′ for supplying a bias voltage to the upper electrode 7 is disposed in the upper layer of the semiconductor layer 6 ′.

  The TFT switch 4 ′ is connected to the lower electrode 14 ′ of the sensor unit 103 ′, and controls reading out of the electric charge accumulated in the lower electrode 14 ′ to the signal wiring 3 ′ by being irradiated with light.

On the other hand, Patent Document 2 proposes a technique for maximizing the area ratio of the semiconductor layer 6 ′ in the sensor unit 103 ′ and improving the light utilization efficiency (fill factor) as shown in FIG. A configuration is also proposed in which the lower electrode 14 ′ is overlapped with the signal wiring 3 ′ and the scanning wiring 101 ′.
JP 2000-137080 A US Pat. No. 5,770,871

  As shown in FIG. 8, when the signal wiring 3 ′ and the lower electrode 14 ′ do not overlap in the vicinity of the TFT switch 4 ′, as shown in FIG. And is scattered by a support substrate or a circuit board disposed on the back surface and becomes stray light and enters the channel portion 4A ′ of the TFT switch 4 ′. As a result, a leakage current from the TFT switch 4 ′ increases. There was a problem.

  Therefore, when the technique described in Patent Document 2 is used and the lower electrode 14 'is overlapped with the signal wiring 3' and the scanning wiring 101 'as shown in FIG. 10, the channel of the TFT switch 4' Since light can be prevented from entering the portion 4A ′, the leakage current from the TFT switch 4 ′ can be suppressed.

  However, when the lower electrode 14 'is overlapped with the signal wiring 3' and the scanning wiring 101 'in this way, the parasitic capacitance between the lower electrode 14' and the signal wiring 3 'is increased, and such a structure. Products that can be used are limited. Note that Patent Document 2 describes that the crosstalk can be reduced to 2% or less by providing an insulating film (Anticoupling Layer).

  That is, as the electromagnetic wave detecting element 10 ′ increases in size, the overlapping portion of the lower electrode 14 ′ and the signal wiring 3 ′ increases and the parasitic capacitance applied to the signal wiring 3 ′ increases, and electronic noise due to the parasitic capacitance can be ignored. Disappear. For this reason, even when an insulating film is provided, the parasitic capacitance between the lower electrode 14 'and the signal wiring 3' remains a problem.

  The present invention has been made to solve the above-described problems, and provides an electromagnetic wave detection element capable of suppressing the occurrence of leakage current from a thin film transistor while suppressing an increase in parasitic capacitance of a signal wiring. Objective.

  In order to achieve the above object, the electromagnetic wave detection element of the present invention is provided corresponding to each intersection of a plurality of scanning wirings and a plurality of signal wirings arranged to cross each other, and a gate is provided on the scanning wiring. A thin-film transistor in which a source electrode is connected to one of the signal wiring and the sensor unit provided corresponding to each intersection, and a drain electrode is connected to the other; and each intersection And a light shielding part formed on a part of the irradiation surface side of the electromagnetic wave including a connection part of the signal wiring with the thin film transistor by a member having a light shielding property to the electromagnetic wave to be detected.

  The electromagnetic wave detection element of the present invention controls the readout of the charge accumulated in the sensor unit by irradiating the target electromagnetic wave with the thin film transistor whose switching characteristics are changed by the electromagnetic wave to be detected by the sensor unit. Has been.

  And in this invention, the light-shielding part by the member which has a light-shielding property with respect to the electromagnetic waves made into a detection object is formed in the irradiation surface side of a part of electromagnetic waves including the connection part with the thin-film transistor of signal wiring.

  As described above, the electromagnetic wave detection element of the present invention forms the light shielding portion by a member having a light shielding property against the electromagnetic wave to be detected only in a part including the connection portion with the thin film transistor of the signal wiring. Generation of leakage current from the thin film transistor can be suppressed while suppressing increase in parasitic capacitance of the wiring.

  In addition, the electromagnetic wave detecting element has a portion that is not connected to the signal wiring of the electrode of either the source electrode or the drain electrode connected to the signal wiring from the end of the signal wiring to the electrode of the signal wiring. When the distance to the opposite end is K1, it is preferable that the concentric circle at a distance K1 from the both ends in the signal wiring direction of the channel portion of the thin film transistor is an area within the intersection range where the signal wiring intersects. Any one of the electrodes is a source electrode when the source electrode is connected to the signal wiring, and is a drain electrode when the drain electrode is connected to the signal wiring.

  In the electromagnetic wave detection element, the sensor unit is formed of a semiconductor layer that generates electric charges when irradiated with the electromagnetic wave to be detected, and a conductive member having a light shielding property against the electromagnetic wave to be detected. An electrode for collecting charges generated in the semiconductor layer, and the light shielding portion may be formed by extending the electrode for collecting charges toward the irradiation surface side of the part of the signal wiring. Good.

  In the electromagnetic wave detection element, an interlayer insulating film having a relative dielectric constant of 2 to 4 and a film thickness of 1 to 4 μm may be provided between the light shielding portion and the signal wiring.

  In the electromagnetic wave detecting element, the light shielding portion may be further formed on a part or all of the irradiation surface side of the scanning wiring.

  Here, the electromagnetic wave means an electromagnetic wave that is mainly detected by the sensor unit. For example, in the case of an electromagnetic wave detection element used in an indirect conversion type radiological image detection apparatus, light emitted by a scintillator corresponds to this. Therefore, the side facing the scintillator of the semiconductor layer is an electromagnetic wave irradiation surface, and the side opposite to the scintillator is an electromagnetic wave non-irradiation surface.

  As described above, according to the present invention, since the light shielding portion made of a member having a light shielding property against the electromagnetic wave to be detected is formed only in a part including the connection portion of the signal wiring with the thin film transistor, It has an excellent effect that generation of a leak current from the thin film transistor can be suppressed while suppressing an increase in parasitic capacitance.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the case where the present invention is applied to the radiation image detection apparatus 100 will be described.

[First Embodiment]
FIG. 1 shows an overall configuration of a radiation image detection apparatus 100 according to the first embodiment. However, a scintillator that converts radiation into light is omitted.

  As shown in the figure, the radiation image detection apparatus 100 according to the present embodiment includes an electromagnetic wave detection element 10.

  The electromagnetic wave detection element 10 includes an upper electrode, a semiconductor layer, and a lower electrode, which will be described later. The sensor unit 103 receives light obtained by converting irradiated radiation by a scintillator, and accumulates charges. The charge accumulated in the sensor unit 103 is stored. A number of pixels each including a TFT switch 4 for reading out are provided two-dimensionally.

  Further, in the electromagnetic wave detection element 10, a plurality of scanning wirings 101 for turning on / off the TFT switch 4 and a plurality of signal wirings 3 for reading out electric charges accumulated in the sensor unit 103 intersect each other. Is provided.

  An electric signal corresponding to the amount of electric charge accumulated in the sensor unit 103 flows through each signal line 3 when any TFT switch 4 connected to the signal line 3 is turned on. Each signal wiring 3 is connected to a signal detection circuit 105 that detects an electric signal flowing out to each signal wiring 3, and each scanning wiring 101 is used to turn on / off the TFT switch 4 in each scanning wiring 101. A scan signal control device 104 for outputting the control signal is connected.

  The signal detection circuit 105 includes an amplification circuit for amplifying an input electric signal for each signal wiring 3. The signal detection circuit 105 detects the amount of electric charge accumulated in each sensor unit 103 as information of each pixel constituting the image by amplifying and detecting the electric signal input from each signal wiring 3 by the amplification circuit. To do.

  The signal detection circuit 105 and the scan signal control device 104 perform predetermined processing on the electrical signal detected by the signal detection circuit 105 and output a control signal indicating signal detection timing to the signal detection circuit 105. The signal processing device 106 is connected to the scan signal control device 104 for outputting a control signal indicating the output timing of the scan signal.

  Next, with reference to FIG.2 and FIG.3, it demonstrates in detail about the electromagnetic wave detection element 10 which concerns on this embodiment. 2 is a plan view showing the structure of one pixel unit of the electromagnetic wave detection element 10 according to the present embodiment, and FIG. 3 is a sectional view taken along line AA of FIG. Yes.

  As shown in FIG. 3, the electromagnetic wave detecting element 10 includes a scanning wiring 101 and a gate electrode 2 formed on an insulating substrate 1 made of alkali-free glass or the like, and the scanning wiring 101 and the gate electrode 2 are connected. (See FIG. 2). The wiring layer in which the scanning wiring 101 and the gate electrode 2 are formed (hereinafter, this wiring layer is also referred to as “first signal wiring layer”) uses Al or Cu, or a laminated film mainly composed of Al or Cu. Although formed, it is not limited to these.

An insulating film 15 is formed on the scanning wiring 101 and the gate electrode 2 so as to cover the scanning wiring 101 and the gate electrode 2, and a portion located on the gate electrode 2 acts as a gate insulating film in the TFT switch 4. To do. The insulating film 15 is made of, for example, SiN _X or the like, and is formed by, for example, CVD (Chemical Vapor Deposition) film formation.

  On the gate electrode 2 on the insulating film 15, the semiconductor active layer 8 is formed in an island shape. The semiconductor active layer 8 is made of, for example, an amorphous silicon film.

  A source electrode 9 and a drain electrode 13 are formed on these upper layers, and a portion between the source electrode 9 and the drain electrode 13 of the semiconductor active layer 8 becomes a channel portion 4A of the TFT switch 4. In the wiring layer in which the source electrode 9 and the drain electrode 13 are formed, the signal wiring 3 is formed together with the source electrode 9 and the drain electrode 13. The source electrode 9 is connected to the signal wiring 3 (see FIG. 2). The wiring layer in which the signal wiring 3, the source electrode 9, and the drain electrode 13 are formed (hereinafter, this wiring layer is also referred to as “second signal wiring layer”) is a laminate mainly composed of Al or Cu, or Al or Cu. The film is formed using, but is not limited to these.

  A contact layer (not shown) is formed between the source electrode 9 and the drain electrode 13 and the semiconductor active layer 8. This contact layer is made of an impurity-doped semiconductor such as impurity-doped amorphous silicon. These constitute the TFT switch 4 for switching.

A TFT protective film layer 11 is formed on almost the whole area (substantially the whole area) of the region on the substrate 1 that covers the semiconductor active layer 8, the source electrode 9, the drain electrode 13, and the signal wiring 3 and is provided with the pixels. ing. The TFT protective film layer 11 is made of, for example, SiN _X or the like, and is formed by, for example, CVD film formation.

A coating type interlayer insulating film 12 is formed on the TFT protective film layer 11. This interlayer insulating film 12 is made of a photosensitive organic material having a low dielectric constant (relative dielectric constant ε _r = 2 to 4) (for example, a positive photosensitive acrylic resin: a copolymer of methacrylic acid and glycidyl methacrylate). And a base polymer mixed with a naphthoquinonediazide-based positive photosensitive agent). In the electromagnetic wave detection element 10 according to the present exemplary embodiment, the interlayer insulating film 12 suppresses the parasitic capacitance between metals disposed in the upper layer and the lower layer of the interlayer insulating film 12 to be low. In general, such a material also has a function as a flattening film, and has an effect of flattening a lower step. Thereby, since the shape of the semiconductor layer 6 disposed in the upper layer is planarized, it is possible to suppress a decrease in absorption efficiency due to the unevenness of the semiconductor layer 6 and an increase in leakage current. A contact hole 16 is formed in the interlayer insulating film 12 and the TFT protective film layer 11 at a position facing the drain electrode 13.

  On the interlayer insulating film 12, the sensor hole is covered so as to cover the pixel region while covering a part of the signal wiring 3 including the connection portion with the TFT switch 4 (see FIG. 2) from the upper surface side. A lower electrode 14 of the portion 103 is formed. The lower electrode 14 is connected to the drain electrode 13 of the TFT switch 4 through the contact hole 16.

  The lower electrode 14 is made of a light-shielding metal in order to suppress the incidence of light on the channel portion 4A. For example, the lower electrode 14 is mainly made of Al, Cu, or Mo, or Al, Cu, Mo. An alloy film or a laminated film is employed. In this embodiment, a 200 nm MoW film is employed as an example.

  Here, the range in which the signal wiring 3 is covered by the lower electrode 14 will be described with reference to FIG.

  In the electromagnetic wave detection element 10 according to the present embodiment, from the end of the source electrode 9 that is not connected to the signal line 3 to the end of the signal line 3 that is connected to the source electrode 9 that is opposite to the source electrode 9. When the distance is K1, the signal wiring 3 or the lower electrode 14 shields the region in the intersection range R where the concentric circles of the distance K1 and the signal wiring 3 intersect from both ends of the channel portion 4A in the direction of the signal wiring 3 respectively. Preferably, this is an ideal amount of crossing that provides the maximum effect.

  For example, when the portion where the signal wiring 3 and the lower electrode 14 intersect is made longer than the intersection range R, the parasitic capacitance between the signal wiring 3 and the lower electrode 14 increases, so the SN ratio in the signal detection circuit 105 deteriorates. On the other hand, since the light enters the TFT switch 4 from the non-arranged portion side (the lower surface side in FIG. 3) of the lower electrode 14, the effect is small.

  On the other hand, when the intersection of the signal wiring 3 and the lower electrode 14 is made shorter than the intersection range R, the light incidence from both sides of the lower electrode 14 in the direction of the signal wiring 3 increases as the amount of intersection decreases. Since the parasitic capacitance between the signal wiring 3 and the lower electrode 14 is reduced and the S / N ratio in the signal detection circuit 105 is improved, a certain effect can be obtained.

  Therefore, it is desirable that the range covered by the lower electrode 14 is not more than the intersection range R.

On the other hand, a semiconductor layer 6 functioning as a photodiode is formed on the lower electrode 14 (see FIG. 3). In the present embodiment, a photodiode having a PIN structure is employed as the semiconductor layer 6, and an n ⁺ layer, an i layer, and a p ⁺ layer are sequentially stacked from the lower layer.

  An upper electrode 7 is formed on the semiconductor layer 6. For the upper electrode 7, for example, a material having high light transmittance such as ITO or IZO (zinc oxide indium) is used.

  A protective insulating film 17 is formed on the upper electrode 7 and the interlayer insulating film 12. The protective insulating film 17 is made of, for example, SiNx or the like, like the TFT protective film layer 11, and is formed by, for example, CVD film formation.

  On the protective insulating film 17, the common electrode wiring 25 is formed of Al or Cu, or an alloy or a laminated film mainly composed of Al or Cu.

  Further, the protective insulating film 17 is provided with a contact portion 27 for connecting the common electrode wiring 25 and the upper electrode 7.

  The contact portion 27 is provided with a contact hole 27A having a protective insulating film 17 formed at the center, and a contact 27B is provided so as to cover the contact hole 27A. The common electrode wiring 25 is electrically connected to the upper electrode 7 through a contact portion 27 provided on the protective insulating film 17.

  As shown in FIG. 4, a scintillator 30 made of GOS or the like is attached to the electromagnetic wave detecting element 10 formed in this way using an adhesive resin 28 having a low light absorption property.

  Next, an example of a manufacturing process of the electromagnetic wave detection element 10 according to the first embodiment will be described with reference to FIGS.

  First, the gate electrode 2 and the scanning wiring 101 are formed on the substrate 1 as the first signal wiring layer (FIG. 6A). This first signal wiring layer is a laminated film with a barrier metal layer made of a low-resistance metal such as Al or Al alloy or a refractory metal, and has a film thickness of about 100 to 300 nm on the substrate 1 by sputtering. Is deposited. Thereafter, the resist film is patterned by photolithography. Thereafter, the metal film is patterned by a wet etch method using an etchant for Al or a dry etch method. Then, the first signal wiring layer is completed by removing the resist.

  Next, an insulating film 15, a semiconductor active layer 8, and a contact layer (not shown) are sequentially deposited on the first signal wiring layer (FIG. 6B). The insulating film 15 is made of SiNx and has a thickness of 200 to 600 nm, the semiconductor active layer 8 is made of amorphous silicon and has a thickness of about 20 to 200 nm, and the contact layer is made of impurity-doped amorphous silicon and has a thickness of about 10 to 100 nm. Deposited by (Plasma-Chemical Vapor Deposition) method. Thereafter, similarly to the first signal wiring layer, resist patterning is performed by photolithography. Thereafter, the semiconductor active region is formed by selectively dry-etching the semiconductor active layer 8 and the contact layer made of the doped semiconductor with respect to the insulating film 15.

  Next, the signal wiring 3, the source electrode 9, and the drain electrode 13 are formed as a second signal wiring layer on the insulating film 15 and the semiconductor active layer 8 (FIG. 6C). Similar to the first signal wiring layer, the second signal wiring layer is a laminated film with a barrier metal layer made of a low-resistance metal such as Al or Al alloy or a refractory metal, or a single refractory metal film such as Mo. It consists of layers and the film thickness is around 100 to 300 nm. Similar to the first signal wiring layer, patterning is performed by photolithography, and the metal film is patterned by wet etching using an etchant for Al or dry etching. At this time, the insulating film 15 is not removed by selectively employing an etching method. A contact layer and a part of the semiconductor active layer 8 are removed by a dry etching method to form a channel region.

  Next, the TFT protective film layer 11 and the interlayer insulating film 12 are sequentially formed on the layer formed as described above (FIG. 6D). The TFT protective film layer 11 and the interlayer insulating film 12 are formed of a single inorganic material, formed by stacking a protective insulating film made of an inorganic material and an interlayer insulating film made of an organic material, or a single layer insulating film made of an organic material. It may be formed by layers. In the present embodiment, the electrostatic capacitance between the lower common electrode wiring 25 and the lower electrode 14 is suppressed, while the TFT protection composed of the photosensitive interlayer insulating film 12 and the inorganic material is used to stabilize the characteristics of the TFT switch 4. The film layer 11 has a laminated structure. For example, the TFT protective film layer 11 is formed by CVD film formation, a photosensitive interlayer insulating film 12 material, which is a coating system material, is applied, prebaked, and then passes through exposure and development steps. Thereafter, firing is performed to form each layer.

  Next, the TFT protective film layer 11 is patterned by photolithography (FIG. 6E). Note that this step is not necessary when the TFT protective film 11 is not disposed.

  Next, an Al-based material or a metal material such as ITO is deposited on the above layer by a sputtering method. The film thickness is around 20 to 200 nm. Patterning is performed by a photolithography technique, and patterning is performed by a wet etching method using a metal etchant or the like or a dry etching method to form the lower electrode 14 (FIG. 6F). As described above, the lower electrode 14 is formed so as to cover the pixel region and to cover a part including the connection portion of the signal wiring 3 with the TFT switch 4 from the upper surface side.

Next, n ⁺ , i, and p ⁺ layers are sequentially deposited from the lower layer by the CVD method to form the semiconductor layer 6 (FIG. 6G). The film thicknesses are n ⁺ layer 50 to 500 nm, i layer 0.2 to ² μm, and p ⁺ layer 50 to 500 nm, respectively. The semiconductor layer 6 is completed by laminating each layer in order, patterning the semiconductor layer 6 by photolithography, and selectively etching with the lower interlayer insulating film 12 by dry etching or wet etching.

Here, the layers are stacked in the order of n ⁺ , i, and p ⁺ , but they may be stacked in the order of p ⁺ , i, and n ⁺ to form a PIN diode. In this case, the TFT switch 4 has the source electrode 9 and the drain electrode 13 reversed.

  Next, the upper electrode 7 and the protective insulating film 17 are formed (FIG. 6H). The upper electrode 7 is formed by depositing a transparent electrode material such as ITO on the upper layer of the layer formed as described above by a sputtering method. The film thickness is around 20 to 200 nm. Patterning is performed by a photolithography technique, and the upper electrode 7 is patterned by a wet etching method using an etchant for ITO or the like or a dry etching method. As the protective insulating film 17, a SiNx film is deposited so as to cover the upper electrode 7 and the interlayer insulating film 12. The film thickness is around 100 to 500 nm. Thereafter, patterning is performed by a photolithography technique, and patterning is performed by a dry etching method to form a contact hole 27A.

  Next, the common electrode wiring 25 and the contact portion 27 are formed (FIG. 6I). For the common electrode wiring 25 and the contact 27B, a metal material such as Al or Cu or an alloy mainly composed of Al or Cu is deposited on the upper layer of the layer formed as described above by a sputtering method. The film thickness is around 100 to 500 nm. Patterning is performed by a photolithography technique, and patterning is performed by a wet etching method using a metal etchant or the like or a dry etching method, thereby forming the common electrode wiring 25 and the contact 27B.

  Finally, the scintillator 30 made of GOS is attached to the electromagnetic wave detection element 10 formed in this manner using an adhesive resin 28 or the like, whereby the electromagnetic wave detection element 10 as shown in FIG. 4 is formed.

  Next, the operation principle of the radiation image detection apparatus 100 having the above structure will be described.

When X-rays are irradiated from above in FIG. 4, the irradiated X-rays are absorbed by the scintillator 30 and converted into visible light. X-rays may be irradiated from below in FIG. Also in this case, X-rays are absorbed by the scintillator 30 and converted into visible light. The amount of light generated from the scintillator 30 is 0.5 to ² μW / cm ² in normal X-ray imaging for medical diagnosis. The generated light passes through the layer of the adhesive resin 28 and irradiates the semiconductor layer 6 of the sensor unit 103 arranged in an array on the TFT array substrate.

The electromagnetic wave detecting element 10 is provided with the semiconductor layer 6 separately for each pixel unit. A predetermined bias voltage is applied to the semiconductor layer 6 from the upper electrode 7 through the common electrode wiring 25, and when light is irradiated, charges are generated inside. For example, when the semiconductor layer 6 has a PIN structure in which an n ⁺ layer, an i layer, and a p ⁺ layer (n ⁺ amorphous silicon, amorphous silicon, and p ⁺ amorphous silicon) are stacked in this order from the lower layer, a negative bias voltage is applied to the upper electrode 7. When the film thickness of the I layer is about 1 μm, the applied bias voltage is about −5 to −10V. When the semiconductor layer 6 is not irradiated with light in such a state, only a current of several to several + pA / mm ² or less flows. On the other hand, when the semiconductor layer 6 is irradiated with light (100 μW / cm ² ) in such a state, a bright current of about 0.3 μA / mm ² is generated. The generated charges are collected by the lower electrode 14. The lower electrode 14 is connected to the drain electrode 13 of the TFT switch 4, and the source electrode 9 of the TFT switch 4 is connected to the signal wiring 3. At the time of image detection, a negative bias is applied to the gate electrode 2 of the TFT switch 4 and held in the off state, and the collected charges are accumulated in the lower electrode 14.

  At the time of image reading, an ON signal (+10 to 20 V) is sequentially applied to the gate electrode 2 of the TFT switch 4 through the scanning wiring 101. As a result, when the TFT switch 4 is sequentially turned on, an electric signal corresponding to the amount of charge accumulated in the lower electrode 14 flows out to the signal wiring 3. The signal detection circuit 105 detects the amount of electric charge accumulated in each sensor unit 103 based on the electric signal flowing out to the signal wiring 3 as information of each pixel constituting the image. Thereby, the image information which shows the image shown with the X-ray irradiated to the electromagnetic wave detection element 10 can be obtained.

  By the way, the electromagnetic wave detection element 10 according to the present exemplary embodiment is formed by extending the lower electrode 14 so as to cover a part including the connection portion of the signal wiring 3 with the TFT switch 4 so as to cover the upper surface side (scintillator 30 side). Yes. As a result, light generated in the scintillator 30 and incident on the connection portion between the signal wiring 3 and the source electrode 9 is prevented from being blocked by the lower electrode 14 and becomes stray light, so that an increase in leakage current can be suppressed. it can.

  Further, the electromagnetic wave detection element 10 according to the present exemplary embodiment can suppress an increase in parasitic capacitance of the signal wiring 3 because the lower electrode 14 is overlapped only on a part of the signal wiring 3.

  Moreover, since the electromagnetic wave detection element 10 according to the present embodiment also serves as a light shielding part that extends the lower electrode 14 and covers a part including the connection part of the signal wiring 3 with the TFT switch 4, the electromagnetic wave detection element 10 There is no need to form a light shielding portion as a separate layer.

[Second Embodiment]
Next, a case where the lower electrode 14 is overlapped with the scanning wiring 101 will be described.

  FIG. 7 is a plan view showing the structure of one pixel unit of the electromagnetic wave detection element 10 according to the second exemplary embodiment. The description of the same parts in FIG. 7 as those in FIG. 2 is omitted. 7 is the same as FIG. 3 described above, and a description thereof will be omitted.

  In the present embodiment, the lower electrode 14 of the sensor unit 103 covers the pixel region while filling the contact hole 16, covers a part including the connection part of the signal wiring 3 with the TFT switch 4 from the upper surface side, and The entire scanning wiring 101 is formed so as to cover from the upper surface side.

  As described above, in the electromagnetic wave detection element 10 according to the present exemplary embodiment, since the lower electrode 14 is formed so as to cover the entire scanning wiring 101 from the upper surface side, the incidence of light from the scanning wiring 101 side is also prevented. Since the influence of stray light can be further suppressed, an increase in leakage current can be further suppressed.

  In addition, according to each said embodiment, although the case where the lower electrode 14 was extended | stretched and used as a light-shielding part was demonstrated, the light-shielding part was formed with the member which has light-shielding property separately from the lower electrode 14. FIG. May be.

  Further, according to each of the above embodiments, since the common electrode wiring 25 is formed in parallel with the signal wiring 3, the signal wiring 3 does not cross the common electrode wiring 25, and the signal wiring 3 is connected to the common electrode wiring 25. Since an increase in the parasitic capacitance of the wiring due to the intersection can be prevented, electronic noise generated in the signal wiring 3 can be reduced.

  In each of the above embodiments, the case where the common electrode wiring 25 is formed in parallel with the signal wiring 3 has been described. However, the present invention is not limited to this, and for example, the common electrode wiring 25 is connected to the scanning wiring 101. And may be formed in parallel.

In each of the above embodiments, the case where the present invention is applied to the radiation image detection apparatus 100 that detects an image by detecting X-rays as electromagnetic waves to be detected has been described. However, the present invention is not limited to this. For example, the electromagnetic wave to be detected may be visible light, ultraviolet light, infrared light, or the like. In addition, the configuration of the radiation image detection apparatus 100 described in the above embodiments (see FIG. 1) and Needless to say, the configuration of the electromagnetic wave detection element 10 (FIGS. 2 to 7) is merely an example, and can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows the whole structure of the radiographic image detection apparatus which concerns on 1st and 2nd embodiment. It is a top view which shows the structure of the 1 pixel unit of the electromagnetic wave detection element which concerns on 1st Embodiment. It is line sectional drawing of the electromagnetic wave detection element which concerns on 1st and 2nd embodiment. It is line sectional drawing of the electromagnetic wave detection element with which the scintillator which concerns on 1st Embodiment was affixed. It is a figure which provides the description of the range covered with a lower electrode. It is a figure for demonstrating the manufacturing process of the electromagnetic wave detection element which concerns on 1st Embodiment. It is a top view which shows the structure of the 1 pixel unit of the electromagnetic wave detection element which concerns on 2nd Embodiment. It is a top view which shows the structure of the 1 pixel unit of the conventional electromagnetic wave detection element. It is line sectional drawing of the conventional electromagnetic wave detection element. It is a top view which shows the other structure of the unit of 1 pixel of the conventional electromagnetic wave detection element.

Explanation of symbols

2 Gate electrode 3 Signal wiring 6 Semiconductor layer 4 TFT switch (thin film transistor)
4A Channel portion 9 Source electrode 10 Electromagnetic wave detecting element 12 Interlayer insulating film 13 Drain electrode 14 Lower electrode (light shielding portion, electrode)
101 Scanning wiring 103 Sensor part R Intersection range

Claims (5)

A plurality of scanning wirings and a plurality of signal wirings arranged so as to cross each other are provided corresponding to each crossing portion, and a gate electrode is connected to the scanning wiring, and corresponds to the signal wiring or each crossing portion. A thin film transistor in which a source electrode is connected to any one of the sensor units provided and a drain electrode is connected to the other, and
For each of the crossing portions, a light shielding portion formed on a part of the electromagnetic wave irradiation surface side including a connection portion with the thin film transistor of the signal wiring by a member having a light shielding property with respect to the electromagnetic wave to be detected;
An electromagnetic wave detecting element comprising: The portion is a distance from an end of the source electrode connected to the signal wiring or the drain electrode not connected to the signal wiring to an end of the signal wiring opposite to the electrode. The electromagnetic wave detecting element according to claim 1, wherein K1 is a region within a crossing range where concentric circles each having a distance K1 and the signal wiring intersect each other from both ends of the channel portion of the thin film transistor in the signal wiring direction. The sensor unit is
A semiconductor layer that generates charges when irradiated with the electromagnetic wave to be detected; and
An electrode that is formed of a conductive member having a light shielding property with respect to the electromagnetic wave to be detected and collects charges generated in the semiconductor layer, and
The electromagnetic wave detecting element according to claim 1, wherein the light shielding portion is formed by extending an electrode that collects the electric charges toward the irradiation surface side of the part of the signal wiring. An interlayer insulating film having a relative dielectric constant of 2 to 4 and a film thickness of 1 to 4 μm is provided between the light shielding portion and the signal wiring.
The electromagnetic wave detection element of any one of Claims 1-3. The electromagnetic wave detection element according to claim 1, wherein the light shielding portion is further formed on a part or all of the irradiation surface side of the scanning wiring.

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