JP2003051587A - Method and device for inspecting direct radiation image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of inspecting a direct radiation image pickup device in which inspections performed by using X-rays are replaced with a simple method while the qualities of the inspections are maintained, and to provide an inspection device used for the method. SOLUTION: This method is used for inspecting a direct radiation image pickup device having a photoelectric conversion element 300 in which an electrode layer 302 for impressing a voltage for reading out converted electric signals on a converting layer 301 which converts radiation into the electric signals. The electrode layer 302 has openings and the photoelectric conversion element 300 is inspected by projecting a near infrared ray upon the electrode layer 302 while a voltage is impressed on the layer 302.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting a direct type radiation image pickup apparatus for picking up an incident radiation image and an inspecting apparatus therefor, and more particularly to an inspection method for a direct type X-ray image pickup apparatus for picking up an X-ray image. Regarding the inspection device.

[0002]

2. Description of the Related Art With the recent progress of semiconductor technology, digitization of radiation equipment applying the technology is progressing.
The digitization of this radiation equipment is to record the images and information stored in conventional equipment on film or paper as digital information, but it is not limited to the ability to transfer images and information in real time, but also to new principles and materials. To develop a higher performance device.

The most familiar radiographic device is a medical X-ray imaging apparatus (X-ray). As far as the X-ray imaging device is concerned, since the sensitivity is improved by digitization, the dose applied to the patient can be reduced and the burden on the patient can be reduced. Further, it is expected to make a great progress such that a still image shooting and a moving image shooting can be performed by one device, which is conventionally a separate device. Therefore, high performance of such a medical device is expected as a great progress in medical care, such as reducing the burden on the patient and improving efficiency.

There are roughly two types of digitized X-ray image pickup devices. One is, as shown in FIG. 14A, an X-ray 100 that has passed through a patient 106 and carries internal information of the patient is converted into light 103 by a phosphor 102, and the light is converted into a semiconductor optical sensor such as a photodiode. The signal is converted into an electric signal using 104. The other is Figure 14.
As shown in (b), the X-ray imaging device directly absorbs the X-rays and converts the X-ray signals into electric signals.

The photoelectric conversion element 1 of the device shown in FIG.
For 07, a diode structure in which a metal electrode is laminated on a layer in which an amorphous material such as amorphous selenium (α-Se) or a crystalline material such as GaAs or silicon is doped with impurities is used.

Further, the transfer circuit 108 for transferring the converted electric signal has a switching element such as a thin film transistor or a MOS transistor made of a semiconductor (silicon or amorphous silicon) and a capacitor for accumulating the electric signal. Those arranged in a dimensional matrix are used. The former is called the indirect type and the latter is called the direct type.

Most of the X-ray image pickup devices currently in practical use are the above-mentioned indirect type, but it is considered that the direct type becomes the main force for the X-ray image pickup device having higher sensitivity.
Because the indirect type converts X-rays into light with a phosphor as described above, and then converts it into an electric signal with a semiconductor photosensor, the conversion efficiency of the phosphor and the photoelectric conversion efficiency of the semiconductor photosensor, and the phosphor There is a problem that the efficiency of converting X-rays into electrical signals is not high because of the absorption of light by the substance (adhesive etc.) between the semiconductor photosensor and the semiconductor photosensor. On the other hand, since the direct type is determined only by the conversion efficiency of the material used for converting X-rays into charges, the conversion efficiency of the X-rays into charges can be higher in the direct type than in the indirect type.

[0008]

In the manufacture of a direct X-ray image pickup device, an inspection using X-rays is required. Figure 15 is X
It is a flowchart which shows the inspection process of a line imaging device. First, impurities are doped in a photoelectric conversion material that converts X-rays into electric charges, and metal electrodes are laminated to manufacture a photoelectric conversion element that is a diode substrate (step S).
1). At this stage, the first inspection using X-rays is performed (step S2). Here, it is inspected whether or not the photoelectric conversion element functions as an element for converting X-rays into electric charges, and whether or not there is a pixel having no output or a pixel having an extra output.

At the same time, the transfer circuit 108 to be attached to the photoelectric conversion element is also manufactured (step S3), and its electrical inspection is also performed (step S4).

The manufactured photoelectric conversion element and the transfer circuit are attached to each other (step S5), and a second inspection using X-rays is performed (step S6). Here, whether the electrodes of the photoelectric conversion element and the transfer circuit of the transfer substrate are electrically connected,
It is inspected whether or not the X-ray imaging apparatus operates without problems.

After that, the photoelectric conversion element and the transfer board module that have been bonded together are used to assemble an X-ray imaging device (step S7). An inspection using the last X-ray is performed (step S8). Here, it is inspected whether or not the X-ray imaging apparatus in the completed state operates.

In order to carry out such an inspection using X-rays, there are costs associated with the management of the X-ray source and the installation of a dedicated shield room for X-ray imaging. In order to provide an X-ray imaging device that is more sensitive than ever and has a price that is easy to spread, it is necessary to reduce the cost.

The present invention has been made in view of the above points, and an inspection method for a direct radiation imaging apparatus and an inspection apparatus therefor in which an inspection using X-rays is replaced with a simple method while maintaining inspection quality. The purpose is to provide.

[0014]

In order to solve the above-mentioned problems, the present invention provides a conversion layer for converting radiation into an electric signal, and an electrode layer for applying a voltage for reading the converted electric signal. A method for inspecting a direct radiation imaging device having a photoelectric conversion element formed, wherein an opening is formed in the electrode layer, while applying a voltage to the electrode layer, by irradiating near infrared rays, The photoelectric conversion element is inspected.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. First, the principle of the present invention will be described.

In the direct type photoelectric conversion element, a semiconductor type photoelectric conversion element causes photoelectric conversion other than X-rays. For example, GaA
Since s is sensitive to light having a wavelength of about 0.8 μm (near infrared light), near infrared light can be used to inspect whether it functions as a photoelectric conversion element.

From the above, as a method of replacing with a simple method while maintaining inspection quality, near infrared light absorbed by a photoelectric conversion element having a semiconductor conversion layer without using X-rays for inspection of a direct X-ray imaging device. To inspect. At this time, since near infrared light cannot pass through the metal film, the metal electrode on the side of the photoelectric conversion element on which X-rays are incident has an electrode structure suitable for inspection by near infrared light, and a GaAs substrate is used for the conversion layer. .

(Embodiment 1) Hereinafter, Embodiment 1 of the present invention
Indicates. FIG. 1 is a diagram showing a photoelectric conversion element used in the present embodiment for converting X-rays into electric charges. In FIG.
1A is a plan view of the photoelectric conversion element viewed from the upper electrode side, FIG. 1B is a plan view of the photoelectric conversion element viewed from the bump metal side, and FIG. 1C is A- of FIG. 1A. A sectional view taken along line A and FIG. 1D are sectional views taken along line BB of FIG.

In FIG. 1, 301 is an N-type high resistance (about 10 ⁶ Ωcm) as a conversion layer having sensitivity to X-rays.
GaAs substrate, 302 is metal organic vapor deposition (MOCV)
P type GaAs layer deposited by (D method) or the like, 303 is an upper electrode as an electrode layer, which is a metal film such as Au (gold) deposited by sputtering, 304 is a metal organic vapor deposition method (M
An N-type GaAs layer deposited by the OCVD method or the like, 305 is a pixel electrode which is a metal film such as Au deposited by sputtering, and 307 is a silicon nitride film (SiNx) deposited by the chemical vapor deposition method (CVD) .

Further, 308 is a barrier metal for forming bumps 309, which is a laminate of titanium, palladium and gold by sputtering, and 309 is a gold bump metal formed by plating. here,
The upper electrode 303 and the pixel electrode 305 are not limited to Au but may be A
u and titanium (Ti) laminated, Au and zinc (Zn)
The alloy of may be used.

FIG. 2 is a sectional view showing a manufacturing process of the photoelectric conversion element. First, MOC is applied to a high resistance P-type GaAs substrate.
An N-type GaAs layer is deposited to a thickness of 2 μm by the VD method, and then Al is vapor-deposited to a thickness of 1 μm by sputtering (FIG. 2A). Then, as shown in FIG. 2, patterning is performed by lithography and etching is performed to form pixel electrodes (FIG. 2B). Further, a silicon nitride film is deposited to a thickness of 1 μm by the CVD method for the purpose of protecting the N-type GaAs layer and the electrode (FIG. 2C). A P-type GaAs layer of 2 μm is deposited on the opposite surface by MOCVD and Au of 1 μm is deposited by sputtering, and an Au electrode is etched between the pixel electrodes as shown in FIG. 1C (FIG. 2D). .

Further, after opening the silicon nitride film in the portion where the Au electrode is present by patterning and etching (FIG. 2 (e)), a barrier metal is sequentially deposited (FIG. 2).
(F)) Finally, a gold bump metal is formed by plating (FIG. 2 (h)).

In order to manufacture a photoelectric conversion element, Ga of 4 inches is used.
When an As semiconductor substrate wafer is used, it has a size of 68 mm square and a thickness of 600 μm. When one pixel is designed with a pitch of 160 μm, the number of pixels of one photoelectric conversion element of 68 mm square is 400 × 400 pixels.

Here, the larger the diameter of the bump metal,
Although the connection resistance with the transfer board can be reduced, the margin for the deviation at the time of bonding becomes small. On the contrary, when the diameter is small, the connection resistance is large. From the above, the diameter of the bump metal is formed to be the optimum diameter in consideration of the connection resistance and the margin for deviation. The height of the bump metal is determined by back calculation from the coating thickness of the adhesive used for bonding.

The operating principle of the photoelectric conversion element of this embodiment will be described with reference to FIG. FIG. 3 is a layer configuration diagram and a band diagram for explaining the operation principle of the photoelectric conversion element. The photoelectric conversion element of this embodiment is a PIN photodiode. FIG. 3A shows the layer structure.
FIG. 3B shows a band diagram in a balanced state in which no voltage is applied, and FIG. 3C shows a band diagram of the photoelectric conversion element when a negative potential is applied to the upper electrode 303 of the photoelectric conversion element.

As shown in FIG. 3B, the upper electrode 303
When no voltage is applied to the N type GaAs layer, the electrons in the N type GaAs layer diffuse to the high resistance P type GaAs substrate 301 and the holes in the high resistance N type GaAs substrate 301 diffuse to the N type GaAs layer. Type GaAs layer 304 and high resistance P type G
At the interface of the aAs substrate 301, a carrier-depleted layer,
A depletion layer 503 is formed.

As shown in FIG. 3C, when a negative voltage is applied to the upper electrode, the high resistance N-type GaAs substrate 301
Holes in the N-type GaAs layer 302 side
Since the electrons 501 in the layer are attracted toward the pixel electrode side, the depletion layer 503 becomes wider than in the state where no voltage is applied. Since the depletion layer easily spreads as the carrier density decreases, the depletion layer is mainly formed in the high-resistance N-type GaAs substrate 301 with P-type G.
It spreads toward the aAs layer 302. This depletion layer has a very high resistance, and most of the voltage applied to the photoelectric conversion element is applied to the depletion layer, so that the electric field of the depletion layer is high. The ease with which the depletion layer spreads is determined by the resistance value of the GaAs substrate used. A high resistance N-type GaAs substrate of about 10 ⁸ Ω · cm can be completely depleted at the internal voltage of the PIN diode (built-in potential: about 1.8 V).

At this time, when the depletion layer is irradiated with light or emitted light, an amount of electrons proportional to the amount of the irradiated light is generated by the photoelectric effect, and the generated electrons 504 are accelerated by the electric field applied to the depletion layer. Pixel electrode 305 without recombining
The holes 505 can reach the upper electrode 303. In addition, the current flowing in the photoelectric conversion element when light or emitted light is not emitted is due to carriers thermally generated in the depletion layer,
It is very small compared to the current generated by the photoelectric effect. From the above, the photoelectric conversion element can generate an electric signal according to the amount of light applied.

The principle of the inspection of this embodiment will be described with reference to FIG. 4 (a) is a schematic diagram of photoelectric conversion, FIG.
(B) is a graph showing the state of the electric field distribution in the photoelectric conversion element. The cross-sectional view of FIG. 4A is a cross-sectional view taken obliquely with respect to the matrix of pixel electrodes in the photoelectric conversion element, and the plan view of the left end portion of FIG. 4A is a plan view showing the cutting. .

The upper electrode of the photoelectric conversion element of this embodiment is
The near infrared light is opened so as to reach the high resistance N-type GaAs substrate. In the inspection, a negative voltage is applied to the photoelectric conversion element, and near infrared light is made incident. In the opening of the upper electrode, near-infrared light passes through the P-type GaAs layer and reaches the high-resistance N-type GaAs substrate, where holes and electrons are generated by the photoelectric effect. At this time, the near-infrared light can penetrate only a few tens of μm from the surface of the semiconductor, so that the depletion layer extends to the place where the near-infrared light can reach.

In order for carriers generated in the vicinity of the interface between the P-type GaAs layer and the high-resistance N-type GaAs substrate to reach the pixel electrode, the velocity of electrons accelerated by the electric field ve ≧ substrate thickness / carrier life . Since the carrier life of the high resistance N-type GaAs substrate is about 1 μsec, the electron velocity ve = 600 μm / 1 μsec = 600 [m / s
ec].

The velocity of the carrier can be expressed as v = μE from the electric field E to be accelerated and the mobility μ of the carrier. G
The carrier mobility of aAs is 0.85 [m ² / V · sec].
Since it is a known value, the required electric field can be obtained. E = 600 [m / sec] /0.85 [m ² / V · s
ec] ≈700 [V / cm].

FIG. 4 (b) shows that the upper electrode of the photoelectric conversion element is -1.
It is the graph which showed the electric field distribution between CD of FIG. 4 (a) when a voltage of 000V is applied. Since the depletion layer spreads from the P layer side, the electric field value is large on the P layer side and decreases as it approaches the N layer. As shown in FIG. 4B, it can be seen that if the voltage applied to the photoelectric conversion element is −1000 V, the electrons generated at a depth of tens of μm from the surface can be detected as an electric signal.

FIG. 5 is a schematic view of the photoelectric conversion element inspection apparatus according to the present embodiment. FIG. 5 shows a front view of the inspection device viewed from the front. In FIG. 5, 701 is a near-infrared light LED (light-emitting diode) light source made of a plurality of light-emitting diodes, 702 is a photoelectric conversion element 703 fixed, and near-infrared light emitted from the near-infrared light source is transmitted. A fixed plate, which is a fixed plate provided with an electrode 709 for applying a voltage to the photoelectric conversion element, a photoelectric conversion element 300, a socket 704 made of an insulator for fitting the photoelectric conversion element,
Reference numeral 705 is a prober including a probe 710 for detecting an electric signal from the photoelectric conversion element, 706 is a prober driving device for moving the prober, 707 is a stage for fixing a socket or the like, and 708 is a voltage for the photoelectric conversion element. Is a power supply for applying.

The power source 708 can apply an arbitrary voltage to the photoelectric conversion element. The prober 705 can be moved in the depth direction and the vertical direction of FIG. 5 by the prober drive device 706.

Further, the inspection apparatus shown in FIG. 5 has a computer system for controlling the inspection apparatus and for taking in the inspection data, a mechanism for conveying the photoelectric conversion element and accurately fixing the photoelectric conversion element to the socket, and raising 702. It is equipped with a mechanism that can lower, lower, and fix.

Hereinafter, each part of the inspection device of FIG. 5 will be described. FIG. 6 is an external perspective view of the socket. The structure of the socket is such that holes 801 penetrating the socket are vacant by the number of pixels of one photoelectric conversion element. At the time of inspection, the bump metal 309 of the photoelectric conversion element is moved so that it just fits in the hole 801 of the socket and is fitted into the socket. Therefore, the hole 801 vacant in the socket is larger than the diameter of the bump metal. Further, a positioning mark 802 for positioning the prober is written on the surface of the socket. The thickness of the socket is a thickness that sufficiently satisfies the mechanical strength and is smaller than the value obtained by adding the length of the probe 710 and the height of the bump metal 309 of the photoelectric conversion element.

FIG. 7 is a schematic plan view and circuit diagram of the prober. In FIG. 7A, 901 is a prober substrate, and 902 is an I that incorporates an amplifier IC and a multiplexer for amplifying and transferring the detected electric signal.
C, 903, 904, and 905 are probe rows in which a number of probes corresponding to one row of photoelectric conversion elements are arranged in a row.
In this embodiment, three rows are arranged.

Reference numerals 906 and 907 denote guard probe rows in which a number of guard probes corresponding to one row of photoelectric conversion elements are arranged in a row. In this embodiment, the probe rows 903 and 90 are provided.
Lined up on the outside of 5. Further, the prober board is provided with viewing windows 908 and 909 for the CCD camera attached to the prober driving device. The cable 910 and the IC 902 are not shown in FIG. 5 because they are on the back side.

The spacing between the probes in the probe rows 903, 904, 905 and the guard probe rows 906, 907 is the same as the pixel pitch of the photoelectric conversion element, and the probe rows 903, 904, 905 and the guard probe row 9 are the same.
The column interval of 05 and 906 is also the same as the pixel pitch of the photoelectric conversion element. In addition, the probe is made of a metal material such as tungsten and has a structure elastic to vertical load.

FIG. 7B shows a circuit diagram of the prober. The probes in the probe rows 903, 904, and 905 are connected to an amplifier IC 912 that amplifies the electric signal detected by each probe. Furthermore, amplifier IC912
A multiplexer 911 is provided at the end of the signal and converts the signal of the amplifier IC into a serial signal. The serial signal is rearranged for each probe column by a transfer destination computer (not shown in FIG. 7) and stored as inspection image data.

FIG. 7C is a detailed circuit diagram of the amplifier IC 912. The amplifier IC has one or more operational amplifiers for amplifying a signal, a capacitor 915 for accumulating an electric signal from the probe, and a reset switch 914 for resetting the potential of the capacitor 915.

In this embodiment, the number of ICs and the number of probes connected to the ICs are not specified. All the probes in the guard probe rows 906 and 907 are grounded. This is because a pixel to which the probe is not in contact is the same as a state in which no voltage is applied, and the electric field distribution around the pixel has different characteristics from the case where the probe is in contact with surrounding pixels. When a photoelectric conversion element is bonded to a transfer substrate to form an X-ray imaging device, the state is the same as when the probe is in contact with the bump metal of all pixels. There must be no pixels that do not touch. Therefore, the guard probe is provided and the guard probe is grounded.

FIG. 8 is a view showing the prober driving means 1000 to which the prober 705 is attached.
FIG. 8A is a plan view seen from the probe side, and FIG.
FIG. 8C is a side view seen from the same direction as, and FIG. 8C is a side view seen from the direction of the arrow in FIG.

In FIG. 8, reference numeral 1004 denotes a fine movement Z stage for adjusting a delicate height such as a contact pressure of a probe.
Reference numeral 005 denotes a pedestal 1005 for moving the prober driving means 1000, a CCD camera 1006 used for positioning the prober, a coarse movement Z stage 1007 for roughly adjusting the height of the prober, a prober and the like. An X stage 1008 for moving in the direction.

The connection between the probe and the bump metal formed on the photoelectric conversion element during the inspection in this embodiment will be described with reference to FIG. In FIG. 9, 300 is a photoelectric conversion element, 309 is a gold bump metal formed on the photoelectric conversion element, 704 is a socket, 710 is a probe attached to a prober, 705 is a prober, and 1105 is a spring portion of the probe.

In order to inspect the photoelectric conversion element, it is necessary to bring all the probes of the prober into contact with the bump metal to establish electrical continuity. The prober driving device moves the prober so that the probe fits into the hole of the socket and then raises the prober to bring the probe into contact with the bump metal.

At this time, as a method for confirming whether the probe and the bump metal are in contact with each other, a method of detecting a current flowing from the photoelectric conversion element is used. Specifically, by applying a negative voltage to the upper electrode of the photoelectric conversion element,
By irradiating light, a current is generated by photoelectric conversion. At this time, it can be determined whether or not the bump metal and the probe are in contact with each other depending on whether or not an electric signal is obtained from the probe that is in contact with the bump metal.

Therefore, in order to bring all the probes into contact with the bump metal, it is sufficient to raise the prober until electric signals are obtained from all the probes. But,
If the height of the probe or bump metal varies, there are probes that have already contacted and probes that have not. A probe that is already in contact with the bump metal is pressed against the bump metal until a probe that is not in contact with the bump metal comes into contact, and in the worst case, the bump metal and the probe may be damaged. For this reason, the probe is provided with a portion serving as a spring portion like 1105.

The inspection process of this embodiment will be described below with reference to FIG. FIG. 10 shows a flowchart of the inspection process of this embodiment. The procedure for inspecting the photoelectric conversion element is that the photoelectric conversion element is conveyed to the socket 704 of the inspection device (step S101), the fixing plate 702 is placed on the photoelectric conversion element, and the photoelectric conversion element is fixed to the socket (step S1).
02). The fixed plate has electrodes 7 connected to the power source 708.
The photoelectric conversion element can be energized by contacting the fixed plate with the upper electrode.

Next, a negative voltage is applied to the photoelectric conversion element (step S103). Prober drive device 706
Moves the prober while looking at the alignment mark on the socket with the CCD camera (step S
104). Raise the prober when it is in place. When the prober is raised, the photoelectric conversion element is irradiated with the LED light, and at the same time, the current generated by the photoelectric conversion is detected by the probe (step S105). Raise the probes until all probes detect current.
When all the probes come into contact (step S106 / Ye
s), The electric current which comes out from each pixel of a photoelectric conversion element is detected.
By repeating the above, all the pixels of the photoelectric conversion element are inspected (step S107).

In the inspection, the reset switch 914 in the amplifier IC 902 is turned on for 1 msec, and the capacitor 915 is turned on.
Reset the potential of. Next, the reset switch 914 is turned off, and the charge detected by the probe is accumulated in the capacitor. After a certain accumulation time, the charge of the capacitor 915 is transferred with the prober lowered.

When the inspection is completed, the photoelectric conversion element 300 is detached from the socket 704 and conveyed (step S10).
7) and the inspection ends (step S108).

Here, it is assumed that the light amount of the LED light and the voltage applied to the photoelectric conversion element in the inspection are set under conditions suitable for inspecting the defective pixel and the variation in characteristics of the photoelectric conversion element.

According to the present embodiment, since the inspection which was conventionally performed by using the X-ray can be performed by using the near infrared ray instead of the X-ray, the management of the X-ray source and the shield room are performed. Is unnecessary, and the cost can be reduced accordingly.

(Embodiment 2) Hereinafter, Embodiment 2 of the present invention
Will be described. FIG. 11 shows an X-ray imaging device in which the photoelectric conversion element 300 is attached to a transfer substrate. Reference numeral 300 is a photoelectric conversion element, and 1302 is a capacitor and a thin film transistor for accumulating electric signals from the photoelectric conversion element 300.
(TFT) switching element is one pixel, and the switching element substrate is formed on the glass substrate by the total number of pixels of the photoelectric conversion elements to be stuck together, and 1303 amplifies and transfers the electric signal output from the switching element substrate. A reading circuit for driving 1304, a vertical driving circuit for driving the switching element, 1305 for regulating the power source used in the reading circuit, the vertical driving circuit, and the switching element substrate, and an electric signal output from the reading circuit as an image. It is a control board that has a role of sending to a computer for processing and transmitting a control signal to each circuit.

A method for obtaining an image will be described below. Figure 1
2 is a circuit diagram of a transfer board and an Amp connected to the transfer board. Although FIG. 12 shows 3 × 3 pixels for simplicity, the number of pixels is not limited to this.

As described above, the transfer board has a structure in which the switching element board and a plurality of circuit boards are connected. In the switching element substrate, the gate electrode of the TFT is connected to the gate lines g1, g2, g3 extending in the horizontal direction, and the gate electrode of the TFT in the horizontal direction is common. The vertical driving circuit 1304 controls g1 to g3.

The drain electrode of the TFT is connected to the signal lines sig1, sig2 and sig3 extending in the vertical direction,
The source electrodes of the vertical TFTs are common. si
g1, sig2, and sig3 are Amp1 and Am, respectively.
It is connected to p2 and Amp3. Amp1 to Amp3
The configuration of is shown in FIG. Each of Amp1 to Amp3 has one or more operational amplifiers 1206 for amplifying a signal, a capacitor 1207 for accumulating an electric signal from the TFT, and a reset switch 1208 for resetting the potential of the capacitor 1207. .

A method for obtaining a two-dimensional image will be described below.
+1 for one gate line to obtain a horizontal line image
A voltage of 5 V is applied to turn on the TFT connected to the gate line. When the TFT is turned on, the electric charge obtained from the photoelectric conversion element accumulated in the capacitor is transferred to the signal transfer line (S
ig1 to Sig3) and stored in the capacitors of Amp1 to Amp3. The charge accumulated in the capacitor is amplified by the operational amplifier and transferred to the sample hold circuit 1202. Here, the capacitors of Amp1 to Amp3 are reset in advance before the charge is transferred.

Here, the transfer of the signal from the capacitor to the sample hold circuit 1202 turns on the TFT for a certain period of time.
Then, apply -5V to the gate line to turn on the TFT.
FF and end. Further, the sample hold circuit 120
From 2, the signal is converted into serial data and sequentially transferred by the multiplexer 1201. A two-dimensional image can be obtained by sequentially repeating this operation for each row.

FIG. 13 shows the layer structure of the switching element substrate used in this embodiment. The switching element substrate is at least a substrate such as glass which is an insulator, and a gate electrode layer 1502 and a lower electrode 1503 formed of a metal film such as chromium, an insulating layer 1504 formed of an insulating film such as an amorphous silicon nitride film, An intrinsic semiconductor layer 1505 formed of hydrogenated amorphous silicon (a-Si: H), an ohmic contact layer 1506 formed of N + type a-Si: H, a metal film such as aluminum, Source electrode 1508, drain electrode 1
It consists of 509.

The capacitor for accumulating the electric signal from the photoelectric conversion element has a lower electrode layer 1503 formed of a metal film such as chromium and an upper electrode layer 1507 formed of a metal film such as aluminum, and an ohmic contact layer 1506. In this structure, the intrinsic semiconductor layer 1505 and the insulating layer 1504 are sandwiched. Further, the lower electrode layer 1503 of the capacitor
Are connected to the connection electrode layer 1510 that connects the source electrode 1508 of the TFT and the bump metal of the photoelectric conversion element.

The capacitor and the TFT are covered with a passivation layer 1511 of an amorphous silicon nitride film in order to prevent moisture and protect from foreign matter. The thickness of each layer is 1500 Å for the gate electrode layer 1502 and the lower electrode layer 1503, 2000 Å for the insulating layer 1504, and 2 for the intrinsic semiconductor layer 1505.
000Å, ohmic contact layer 1509 is 750
Å, the upper electrode layer 1507, the source electrode 1508, the drain electrode 1509 and the connection electrode layer 1510 have a thickness of 1 μm. However, the film thickness of each layer is not limited to this, and the optimum film thickness is used.

In the inspection method shown in this embodiment, the X-ray image pickup apparatus as shown in FIG. 12 is irradiated with a near infrared light LED having a photoelectric conversion element having a sensitivity, and at that time, an output image is taken in. This is a method of inspecting functions such as connection between both transfer boards.

[0066]

As is apparent from the above description, according to the present invention, it is possible to perform an inspection, which was conventionally performed using X-rays, by using near infrared rays instead of X-rays. Therefore, it became unnecessary to manage the radiation source, to install a shield room, and to qualify for handling.

Therefore, the manufacturing cost and efficiency of the X-ray imaging device can be reduced.

For these reasons, a high-performance X-ray imaging device can be set at a reasonable price and can be widely used.

[Brief description of drawings]

FIG. 1 is a diagram showing a photoelectric conversion element used in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of a photoelectric conversion element.

3A and 3B are a layer configuration diagram and a band diagram for explaining the operation principle of the photoelectric conversion element.

4A and 4B are a schematic diagram and a graph of electric field distribution for explaining the principle of inspection according to the first embodiment.

FIG. 5 is a sectional view of an inspection device for inspecting a photoelectric conversion element.

6 is a perspective view of a socket of the inspection device of FIG.

7 is a plan view and a circuit diagram of a prober of the inspection apparatus of FIG. 5, and a circuit diagram of an amplifier IC on the prober.

FIG. 8 is a three-sided view showing a prober driving means provided with a prober.

FIG. 9 is a perspective view showing how the prober and bump metal are connected.

FIG. 10 is a flowchart showing an inspection process of the first embodiment.

FIG. 11 is a perspective view of an X-ray imaging apparatus used in the second embodiment.

FIG. 12 is a circuit diagram of a transfer circuit and a circuit diagram of an amplifier in the transfer circuit.

FIG. 13 is a cross-sectional view showing a layer structure of a switching element substrate of a transfer circuit.

FIG. 14 is a schematic sectional view of an indirect X-ray imaging device and a direct X-ray imaging device.

FIG. 15 is a flowchart showing a manufacturing process of a direct type X-ray imaging device.

[Explanation of symbols]

300 photoelectric conversion element 301 High resistance N type GaAs substrate 302 P-type GaAs layer 303 upper electrode 304 N-type GaAs layer 305 pixel electrode 307 Silicon nitride film 308 barrier metal 309 bump metal

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification symbol FI theme code (reference) H01L 31/0264 H01L 31/08 L H04N 5/32 27/14 K FF term (reference) 2G088 EE01 FF02 GG21 JJ05 JJ37 LL26 4M118 AA09 AB01 BA04 BA05 BA19 CA05 CB02 CB05 DA34 EA01 FB09 FB13 FB16 GA10 HA31 5C024 AX11 CY44 EX04 EX21 HX02 5F088 AA03 AB07 BA20 BB06 BB07 EA04 FA01 FA09 GA05 HA12 KA02 KA02 LA02 KA02

Claims (10)

[Claims] 1. A conversion layer for converting radiation into an electric signal,
A method for inspecting a direct radiation imaging apparatus having a photoelectric conversion element in which an electrode layer for applying a voltage for reading the converted electric signal is formed, wherein an opening is formed in the electrode layer, A method for inspecting a direct-type radiation imaging device, comprising inspecting the photoelectric conversion element by irradiating near infrared rays while applying a voltage to the electrode layer. 2. By irradiating the near infrared ray,
The method for inspecting a direct radiation imaging apparatus according to claim 1, wherein the presence or absence of a pixel defect in the photoelectric conversion element or the photoelectric conversion characteristic of the photoelectric conversion element is inspected. 3. The photoelectric conversion element is connected to a transfer substrate that transfers the read charges, and the photoelectric conversion element and the transfer substrate are connected by irradiating the near infrared rays, or the transfer substrate. 2. The method for inspecting a direct radiation image pickup apparatus according to claim 1, wherein the operation of step 1 or the operation of the photoelectric conversion element is confirmed. 4. A conversion layer for converting radiation into an electric signal,
A direct-type radiation imaging apparatus inspection apparatus having a photoelectric conversion element having an electrode layer for applying a voltage for reading the converted electrical signal, wherein an opening is formed in the electrode layer, A near-infrared source for irradiating infrared rays, a prober for detecting an electric signal for each pixel of the photoelectric conversion element in a state in which a voltage is applied to the electrode layer, and a photoelectric conversion element of the photoelectric conversion element based on the signal detected by the prober. An inspection apparatus for a direct radiation imaging apparatus, comprising: an inspection unit. 5. The inspection apparatus for a direct radiation imaging apparatus according to claim 4, further comprising a socket for connecting a pixel electrode of the photoelectric conversion element and the probe. 6. The inspection apparatus for a direct radiation imaging apparatus according to claim 4, further comprising a fixing plate that transmits near infrared rays and fixes the photoelectric conversion element. 7. The prober driving means for moving the prober is further provided.
Inspection device of the direct radiation imaging device described. 8. The inspection apparatus for a direct radiation imaging apparatus according to claim 5, further comprising a stage for fixing the socket. 9. The fixing plate has an electrode for supplying power to the photoelectric conversion element.
Inspection device of the direct radiation imaging device described. 10. The transfer substrate according to claim 3, wherein a capacitor for storing charge and a thin film transistor (TFT) which is a switching transistor are formed on at least an insulating substrate, and the layer structure is formed of metal such as chromium. Insulating layer composed of first electrode and amorphous silicon nitride film, hydrogenated amorphous silicon layer (a-Si: H)
And a channel layer of a TFT made of a capacitor, a dielectric layer of a capacitor, and an ohmic contact layer of a TFT made of an electronically driven n ⁺ hydrogenated amorphous silicon layer (n ⁺ a-Si: H), and a signal line, a source and a drain of the TFT. The direct-type radiation imaging apparatus according to claim 3, wherein the direct-type radiation imaging apparatus is a transfer substrate including a second electrode layer formed of aluminum as an electrode and a third electrode for electrically and mechanically connecting to a photoelectric conversion element.