JP2002181945A - Radiation detecting device, its manufacturing method, and radiation image pickup system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly sensitive and large-area radiation detecting device by connecting a semiconductor converting substrate for converting radiation and a signal processing substrate for processing its signals by a conductive adhesive. SOLUTION: In a GaAs substrate 101 for detecting X-rays, an Al membrane 102 and a metal bump 103 are formed. On an insulating substrate 106, TFTs or capacitors 108 and signals wires 109 are arranged. An insulating protective membrane 107 is partially opened, and a metal pad 105 made of a membrane of aluminum is formed on the insulating protective membrane 107. The conductive adhesive 104 is applied onto the metal pad 105. The metal bump 103 on the GaAs substrate 101 is heated, pressed, and connected in an embedded state to the conductive adhesive 104 applied to the metal pad 105 on the insulating substrate 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a radiation detecting device,
In particular, the present invention relates to a direct radiation detection device that directly converts radiation into an electric signal.

[0002]

2. Description of the Related Art In a conventional X-ray imaging apparatus, X-rays are converted into visible light by a scintillator and imaged on a film, but with the shift from an imaging method using this film to a digital image processing method. The development of a contact type sensor is underway. This contact type sensor has a photoelectric conversion element and a signal processing unit formed on a large-area substrate by developing a photoelectric conversion semiconductor material typified by hydrogenated amorphous silicon (hereinafter abbreviated as a-Si). It is read by a double optical system. In particular, a-Si is used not only as a photoelectric conversion material but also as a TFT (thin film t) for signal reading.
Since it can also be used as a ransistor, the photoelectric conversion semiconductor layer and the semiconductor layer of the TFT can be formed simultaneously.

Further, it is compatible with a switch element such as a TFT and a capacitor element formed at the same time, and can be formed simultaneously as a common film due to the same film configuration. Can be Capacitor capacitors also include an insulating layer in the middle layer,
A high-performance photoelectric conversion device that can be formed with favorable characteristics and can output optical information obtained by a plurality of photoelectric conversion elements with a simple configuration can be provided. Thus, it is possible to provide a low-cost, large-area, high-performance, high-performance facsimile, image scanner, and X-ray imaging apparatus.
When X-rays are detected by the contact type sensor using a-Si, an indirect X-ray detector is configured in which the X-rays are converted into visible light by a scintillator and then photoelectrically converted.

On the other hand, in order to increase the transfer efficiency of X-rays, that is, to increase the sensitivity of an X-ray detector, a GaAs single crystal semiconductor having good compatibility with X-rays is used, and X-rays are directly transmitted to an electric signal. Attention has been paid to a direct type X-ray detector for converting to X-ray. This is because, by directly absorbing X-rays into a GaAs single crystal semiconductor, there is no light conversion by the scintillator, so that the transfer efficiency of generated carriers can be improved. When connecting a semiconductor conversion substrate made of GaAs with TFTs and capacitors formed in a matrix on an insulating substrate for signal reading, an anisotropic technology generally used for bonding fine patterns to each other is commercially available. Electrical connection is made using an electrically conductive film (ACF).

[0005]

However, in the above-mentioned conventional example, it is difficult to produce a single crystal semiconductor, and it is difficult to use it as a sensor having a large area. Even if a large-area sensor is manufactured, a problem occurs when the semiconductor conversion substrate and the insulating substrate are connected by an anisotropic conductive film by heating pressure. For example, when connecting a large-area semiconductor conversion substrate on which metal bumps are formed and an insulating substrate on which TFTs and capacitors are formed in a matrix at a pressure of 30 to 40 kg / cm ² , a large load is applied. Substrate is destroyed. Further, thermal stress applied to the device due to thermal compression bonding at a high temperature poses a problem.

Accordingly, the present invention provides a direct type radiation detecting apparatus for directly converting radiation into an electric signal and reading the radiation, when connecting a semiconductor conversion substrate for converting radiation to an electric signal and an insulating substrate having a TFT and a capacitor. Another object of the present invention is to provide a highly sensitive and highly reliable X-ray detector by preventing troubles caused by heating and pressurization.

[0007]

In order to solve the above-mentioned problems, the present invention provides a metal bump formed on a semiconductor conversion board for converting radiation into an electric signal, and a signal processing board for reading and processing the electric signal. In the radiation detection device connected to the metal pad formed thereon, in a state where the metal bump on the semiconductor conversion substrate is embedded in the conductive adhesive applied to the metal pad on the signal processing substrate,
It is electrically connected.

That is, according to the present invention, a metal bump on a semiconductor conversion board for detecting radiation and converting it into an electric signal is embedded with a conductive adhesive applied to a metal pad on a signal processing board for reading and processing the electric signal. By providing the radiation detection device with high sensitivity, large area and high reliability, it is possible to reduce the heating and pressurization at the time of connection and to make sure the connection.

[0009]

Next, embodiments of the present invention will be described with reference to the drawings.

[Embodiment 1] FIG. 1 is a sectional view of a main part of a radiation detecting apparatus according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a state where metal bumps formed on a semiconductor conversion substrate are connected to metal pads formed on an insulating substrate.

Reference numeral 101 denotes a single crystal semiconductor substrate for detecting X-rays, which uses GaAs. Semiconductor substrate 10
A metal film is formed on the surface of 1 by sputtering, resistance heating evaporation, electron beam evaporation, or the like. In the present embodiment, an aluminum film (Al film) 1 is formed by sputtering.
02 is formed. This is a film for improving adhesion and conductivity when forming the metal bump 103. The metal bump 103 is formed by electrolytic plating, and uses gold. Others include chrome, titanium,
Molybdenum and copper can be used. Metal bump 10
The diameter of 3 is in the range of 10 to 160 μm. 160μ
If it is more than m, it will exceed the pixel size,
If the thickness is 10 μm or less, a portion that is not formed due to dust comes out and causes non-contact. The height of the metal bump 103 is in the range of 5 to 150 μm. When it is 150 μm or more, at the time of etching,
This is because the tip of the bump becomes thin and the metal bump formed in a dot shape varies, and if it is 5 μm or less, the formed bump does not sink into the conductive adhesive. The above numerical range is a value in consideration of the arrangement pitch of the TFTs or capacitors of the signal processing substrate to be connected and the reliability of the connection. In the present embodiment, the height of the metal bump 103 is formed at 70 ± 3 μm. With the above configuration, a semiconductor conversion substrate that converts X-rays into an electric signal is formed.

Reference numeral 106 denotes an insulating substrate, and reference numeral 108 denotes TFTs or capacitors arranged on the insulating substrate 106 in a matrix. Reference numeral 109 denotes a signal line, which is a wiring film for reading an input signal. 107 is an insulating protective film. Reference numeral 105 denotes a metal pad formed by opening a part of the protective film 107 and formed with aluminum by sputtering similarly to the Al film 102. For the metal pad 105, chromium, titanium, molybdenum, copper, or gold can be used. With the above configuration, a signal processing substrate that reads and processes an electric signal photoelectrically converted from X-rays by the GaAs substrate 101 is configured.

Reference numeral 104 denotes a conductive adhesive, which is applied in a dot shape on a metal pad 105 formed on a signal processing substrate, and is applied with a cross-sectional area of 1.1 times or more that of the metal bump 103. This means that the metal bump 103 is
This is because the connection is performed in a state where the conductive adhesive 104 is embedded in the conductive adhesive 104. The viscosity of the conductive adhesive 104 is 10 to 200 Pascal second. 10 Pascal
This is because if the time is shorter than the second, the liquid will be dropped during application. On the other hand, if it is more than 200 Pascal-second, it is impossible to apply uniformly when applying. In this embodiment, the manufacturer uses LS-109 epoxy-based conductive adhesive manufactured by Asahi Chemical Laboratory, has a viscosity of 75 Pascal-second, and has a height of 60 μm by a screen method. The conductive particles mixed in the conductive adhesive 104 are made of any of gold, silver, and copper, or a mixture thereof, and the size of the conductive particles is 50 μm or less. If the thickness is 50 μm or more, the viscosity is low and the viscosity drops.

Metal bump 103 on GaAs substrate 101
Is connected to the conductive adhesive 104 applied to the metal pad 105 on the insulating substrate 106 in an embedded state by applying heat and pressure. Height 70 ± 3μ
By forming the metal bumps of m, the connection can be made with a low pressure, and the GaAs substrate 101 and the insulating substrate 106 can be prevented from being broken by the pressure. As a result, Ga
Carriers generated by X-ray detection on the As substrate 101 can be moved to the metal pad 105 via the conductive adhesive 104. Since the metal bump 103 is embedded in the conductive adhesive 104, the contact area increases,
Connection with low resistance becomes possible.

FIG. 2 is a cross-sectional view showing a state in which the height of the conductive adhesive 104 formed by the screen method on the metal pads 105 formed in a matrix on the insulating substrate 106 varies.

FIG. 3 shows the conductive adhesive 1 of FIG.
FIG. 4 is a cross-sectional view showing a state in which the metal bumps 103 on the GaAs substrate 101 are connected so as to have no uncontacted portions. 70 ± 3μ height formed on the GaAs substrate 101
m metal bumps 103 are connected without a non-contact state, so the height of the conductive adhesive 104 is 60 μm,
20 to 80 of the metal bump 103 and the conductive adhesive 104
% Embedded in contact. This is because if the contact is small, the resistance becomes high, and if the contact is large, it causes a short circuit with an adjacent pixel.

[Embodiment 2] FIG. 4 is a sectional view of a main part of a radiation detecting apparatus according to another embodiment of the present invention. FIG. 4 is a cross-sectional view illustrating a connection state between a metal bump on a semiconductor conversion substrate and a metal pad on an insulating substrate.

A single crystal semiconductor substrate 101 for detecting X-rays uses GaAs. Reference numeral 102 denotes a film for improving adhesion and conductivity when forming the metal bump 103, and aluminum is formed by sputtering. The metal bump 103 is formed by electrolytic plating, and uses gold. The metal bump 103 is formed with a height of 70 ± 3 μm.

Reference numeral 106 denotes an insulating substrate, and reference numeral 108 denotes TFTs or capacitors arranged on the insulating substrate 106 in a matrix. Reference numeral 109 denotes a signal line, which is a wiring film for reading an input signal. 107 is an insulating protective film. Reference numeral 105 denotes a metal pad formed by opening a part of the protective film 107 and formed with aluminum by sputtering similarly to the Al film 102.

Reference numeral 104 denotes an electrically conductive adhesive. The manufacturer uses an LS-109 epoxy-based electrically conductive adhesive manufactured by Asahi Chemical Research Laboratories, has a viscosity of 75 Pascal second, and increases the height by a screen method. Formed at 100 μm.

Reference numeral 401 denotes an insulating protective film. Al film 1
02 with the conductive adhesive 104 in contact with GaAs.
When a carrier generated by X-ray detection on the substrate 101 flows to the metal pad 105, a local battery is formed at a contact portion between the Al film 102 and the conductive adhesive 104, and the Al film 1
Corrosion occurs in 02. Therefore, in order to prevent the conductive adhesive 104 from contacting the Al film 102, the insulating protective film 4
01 is formed.

With the above structure, the metal bump 103 on the GaAs substrate 101 and the metal pad 105 on the insulating substrate 106
Can be connected to move the carrier generated by X-ray detection on the GaAs substrate 101 to the metal pad 105. In this embodiment mode, the insulating protective film 401 is formed,
The conductive adhesive 104 is formed to have a height of 100 μm with respect to the height of the metal bumps 103 of 70 ± 3 μm, and the GaAs substrate 101 and the insulating substrate 106 are connected. For this reason, even if excessive pressure is applied during connection, the conductive adhesive 104
The contact area with the metal bump 103 can be increased without contacting the film 102. As a result, the contact resistance can be further reduced.

FIG. 5 shows the X-ray of the radiation detecting apparatus according to the present invention.
It shows an example of application to a line diagnostic system.

X-ray 60 generated by X-ray tube 6050
Reference numeral 60 denotes a photoelectric conversion device 6 which transmits through a chest 6062 of a patient or a subject 6061 and has a semiconductor conversion board mounted thereon.
040. The subject 606
1 contains information on the inside of the body. Photoelectric conversion device 604
0 performs photoelectric conversion of the X-ray in response to incidence of the X-ray to obtain an electric signal. This electric signal is converted into a digital signal, image-processed by an image processor 6070, and can be observed on a display 6080 in the control room.

This image information can be transferred to a remote place by a transmission means such as a telephone line 6090, and can be displayed on a display 6081 such as a doctor room at another place or stored in a storage means such as an optical disk. It is also possible for a doctor to make a diagnosis. It can also be recorded on a film 6110 by a film processor 6100.

In the above embodiment, an X-ray imaging system has been described as an example. However, radiation means α, β,
It is assumed that it can be converted to an electric signal, including γ rays.

[0027]

As described above, the present invention relates to a direct type radiation detecting device for directly converting radiation into an electric signal and reading the radiation, and a semiconductor conversion substrate for detecting radiation and a TF.
By connecting an insulating substrate having T and a capacitor, that is, a signal processing substrate, with a conductive adhesive, a high-sensitivity, large-area radiation detecting apparatus can be provided. Furthermore, by connecting the metal bumps formed on the semiconductor conversion substrate in a state where the metal bumps are embedded in the conductive adhesive applied to the metal pads formed on the signal processing substrate, high reliability without disconnection defects is obtained. A radiation detection device can be provided, and the yield of products can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a connection state between a metal bump and a metal pad in the first embodiment.

FIG. 2 is a cross-sectional view showing a state where the height of a conductive adhesive varies.

FIG. 3 is a cross-sectional view showing a state in which metal bumps are connected to a conductive adhesive that has varied.

FIG. 4 is a cross-sectional view showing a connection state between a metal bump and a metal pad in a second embodiment.

FIG. 5 is a diagram showing an example of application of the radiation detection device according to the present invention to an X-ray diagnostic system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 101 Semiconductor conversion substrate 102 Al film 103 Metal bump 104 Conductive adhesive 105 Metal pad 106 Insulating substrate 107 Insulating protective film 108 TFT or capacitor arranged in a matrix 109 Signal line 401 Insulating protective film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G088 EE01 FF02 GG21 JJ05 JJ33 JJ37 4M118 AA01 AA10 AB01 BA06 CB02 FB09 FB13 FB16 FB25 HA31 5C024 AX11 AX16 CX41 CY47 EX21 5F088 AB07 BB07 EA04 FA08

Claims (15)

[Claims] 1. A radiation detecting apparatus comprising: a metal bump formed on a semiconductor conversion substrate for converting radiation into an electric signal; and a metal pad formed on a signal processing substrate for reading and processing the electric signal. A radiation detection apparatus, wherein the metal bumps of the semiconductor conversion board and the metal pads of the signal processing board are electrically connected via a conductive adhesive. 2. The metal bump on the semiconductor conversion substrate,
The radiation detection apparatus according to claim 1, wherein the radiation detection apparatus is electrically connected to the signal processing board while being embedded in the conductive adhesive applied to a metal pad on the signal processing board. 3. A metal bump on the semiconductor conversion substrate,
The radiation detection apparatus according to claim 1, wherein the radiation detection apparatus is connected to the conductive adhesive applied to the metal pad on the signal processing board by applying heat and pressure. 4. The radiation detection apparatus according to claim 1, wherein the metal bump formed on the semiconductor conversion substrate is formed of one of chromium, titanium, molybdenum, copper, and gold. 5. The radiation detecting apparatus according to claim 1, wherein the diameter of the metal bump formed on the semiconductor conversion substrate is 10 to 160 μm. 6. The radiation detecting apparatus according to claim 1, wherein the height of the metal bump formed on the semiconductor conversion substrate is 5 to 150 μm. 7. The method according to claim 7, wherein the metal pad formed on the signal processing substrate includes chromium, titanium, aluminum, molybdenum,
The radiation detection device according to claim 1, wherein the radiation detection device is formed of one of copper and gold. 8. The method according to claim 1, wherein the conductive adhesive is applied to a metal pad on the signal processing board in a dot shape, and the cross-sectional area of the dot is 1.1 times or more the cross-sectional area of the metal bump on the semiconductor conversion board. The radiation detection apparatus according to claim 1, wherein 9. The radiation detecting apparatus according to claim 1, wherein the conductive adhesive is an epoxy-based adhesive. 10. The conductive adhesive has a viscosity of 10-2.
The radiation detection apparatus according to claim 1, wherein the radiation detection apparatus is 00 Pascal-second. 11. The radiation detecting apparatus according to claim 1, wherein the conductive particles mixed in the conductive adhesive are made of one of gold, silver, and copper, or a mixture thereof. 12. The radiation detection apparatus according to claim 1, wherein the size of the conductive particles mixed in the conductive adhesive is 5 to 100 μm. 13. The radiation detecting apparatus according to claim 1, wherein an insulating protective film is applied to a portion of the semiconductor conversion substrate other than where the metal bump is formed. 14. A method of manufacturing a radiation detecting device for connecting a metal bump formed on a semiconductor conversion substrate for converting radiation into an electric signal and a metal pad formed on a signal processing substrate for reading and processing the electric signal. Applying a conductive adhesive to a metal pad on the signal processing board; heating the conductive adhesive applied on the metal bump and the metal pad on the semiconductor conversion board; Pressing the bumps so as to be embedded in the conductive adhesive and connecting the bumps to the conductive adhesive. 15. A radiation source for irradiating a subject with radiation, and detecting the radiation.
A radiation imaging system, comprising: the radiation detection device according to any one of the preceding items, an image processing unit that digitally converts the detected signal and performs image processing, and a display unit that displays the processed image.