JPS6286855A - Solid-state imaging device for radiation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to scanning circuits and radiation, especially X1! The present invention relates to a radiation solid-state imaging device in which a photoconductive layer that receives light and generates carriers is laminated.

[Prior Art 1] Conventionally, as a solid-state imaging device for radiation, one in which a phosphor layer is disposed above a photodiode is known, as shown in, for example, Japanese Patent Laid-Open No. 51-120188.

That is, as shown in FIG. 3, a phosphor layer 4 is disposed on a photodiode 2 provided on a semiconductor substrate 1 with a thin oxide film 3 interposed therebetween. 5 is a reflective film, and 8.7 is a MOS switch. When the radiation 8 enters the phosphor M4, the phosphor layer 4 converts the radiation into light, which enters the photodiode 2 and is converted into electrical signals 4. MOS switch6. ? When conductive, electrical signals can be taken out from the output lines 9.

Conversion of X-rays to light is achieved by S:Tb activation G, which has the highest conversion efficiency.
Even dλ03 is at most! It was about 5%, and high conversion efficiency could not be obtained in the conversion system of radiation → light → electrical signal with such a conventional structure.

In addition, the light emitted from the phosphor is emitted in all directions, and the light is scattered by other phosphor particles, so the incident X-ray image in the phosphor layer becomes blurred. On the other hand, a solid-state imaging device using ordinary Si as a light receiving part has low sensitivity due to the low X-ray absorption rate of Si.

[Problem to be Solved by the Invention 1] An object of the present invention is to solve the above-mentioned conventional drawbacks, and to provide a radiation solid-state imaging device having a high conversion efficiency and a simple structure.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a solid-state imaging device in which a scanning circuit section and a photoconductive film section are laminated.
It is characterized in that the photoconductive layer is made of a photoconductive layer with high X-ray absorption ability. Further, it is characterized in that the base layer is made of heavy metal.

[Function 1] According to the present invention, a heavy metal layer is used for the base electrode and a photoconductor with high X-ray absorption ability is used for the photoconductor layer, so a solid-state imaging device for radiation with a simple structure and high efficiency can be obtained. is obtained.

[Example J Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of an embodiment of the present invention in which the scanning circuit is a MOS type.

In the figure, 100 is a scanning circuit section, and 200 is a photoconductor section. 11 is a semiconductor substrate such as Si, 12 is a source, 1
3 is a gate, 14 is a drain, and 15 is an output line. 1
B is an insulating layer made of 5i02, 5i3Na, phosphosilicate glass, polyimide, etc., 17B is a secondary electrode that partitions the picture element, 17A is a primary electrode that connects the secondary electrode and the source, and 17A and 17B are the base electrodes. Form. Note that the base electrode is made of No., W, or Pt in order to shield the primary electrode and the secondary electrode and protect the scanning circuit section.

The thickness of the heavy metal layer formed by vapor deposition or sputtering using heavy metals such as Au and Pb is 0.1 gm to 1 gm.
It is mm. Reference numeral 18 denotes a photoconductor layer which is a feature of the present invention and is made of Bi, GeO, Bi, 2, which has a high X-ray absorption ability.
SiO,. .

PbO, PbS, Pb5e, PbTe, etc. are used. The photoconductor layer may be formed on the secondary electrode 17B by sputtering or vapor deposition, or the granular crystals of the photoconductor described above may be dispersed and coated in an organic photoconductor such as polyvinyl carbazole. It can also be formed by coating a polyester solution dispersed in a binder containing a charge transport aid such as ZnO powder.

The thicker the photoconductor 18, the greater the X-ray absorption.

A desirable thickness is 10 gm to 1 mm.

Among the various photoconductors mentioned above, 8++2GeO. is X
The conversion efficiency of rays into photocarriers is high, and the absorption rate of X-rays is about 80% at a thickness of 1 mm.

Reference numeral 19 denotes a picture element separation layer for preventing leakage and color mixing between picture elements. Grooves are formed in the photoconductor R18 by plasma etching, etc., and 5i02, Si3 are formed in the grooves.
An insulator such as N4 is formed by a CVD method, or polyimide is filled by a photocuring method. 20 is a transparent electrode with ITO on the surface of the photoconductor layer 18 and the picture element separation layer 19.
It is sputtered or vapor-deposited.

FIG. 2 shows another embodiment of the present invention. In this embodiment, the scanning circuit is composed of thin film transistors (TPT). In FIG.
In the PT, 22 is the source, 23 is the gate, 24 is the drain,
2B is an insulating layer, and the other parts are the same as the embodiment shown in FIG. 1, so the explanation will be omitted.

Increasing the thickness of photoconductor layer 18 requires increasing the bias voltage. Since the breakdown voltage of TPT is higher than that of MOS,
If the scanning circuit is made of TPT, the photoconductive layer can be thickened per day, and the conversion efficiency from X-rays to light can be increased accordingly. Furthermore, TPT is more suitable for large-area X-ray images than crystalline Si scanning circuits.

Also, the method of forming the photoconductive layer on the secondary electrode 17B was described earlier.1 For example, Bi1□G e O,
.

It is also possible to construct a scanning circuit on this single crystal using thin film technology, and when using such a manufacturing method, TPT can be manufactured more easily than MOS.

[Effects of the Invention] As explained above, according to the present invention, a heavy metal layer is used for the base electrode and a photoconductor with high X-ray absorption ability is used for the photoconductor layer, so efficiency can be achieved with a simple configuration. A high quality solid-state imaging device for radiation can be obtained.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional diagram of an embodiment of the present invention, FIG. 2 is a schematic cross-sectional diagram of another embodiment of the present invention, and FIG. 3 is a cross-sectional diagram of a conventional radiation solid-state imaging device. 1.11...Substrate, 2...Photodiode, 4...
Phosphor layer. 17B... Secondary electrode, 18... Photoconductor layer, 18.
... Picture element separation layer, 20 ... Transparent electrode, 100 ... Scanning circuit section, 200 ... Photoconductor section. Figure 1 Figure 3 Procedural amendment February 13, 1986 Director General of the Patent Office Michibu Uga, Hon. 1, Indication of the case, Patent Application No. 80-226901 2, Name of the invention, Solid-state imaging device for radiation 3, Amendment Patent applicant Fuji Photo Film Co., Ltd. 4, agent address: Maison Hirakawa 3F, 2-5-2 Mokawa-cho, Chiyoda-ku, Tokyo 102 Tel: (03) 239-57505;
Date of amendment order 6. Column ``3. Detailed description of the invention'' of the specification to be amended. rS:
Correct Tb activation Gd203J to rGd202S:Tb J. 2) Delete "From r MOS" on page 7, line 5. that's all

Claims (1)

[Claims] 1) A solid-state imaging device in which a scanning circuit section, a base electrode, and a photoconductive film section are laminated, characterized in that the photoconductive layer is made of a photoconductive layer with high X-ray absorption ability. solid-state image sensor. 2) The solid-state imaging device for radiation according to claim 1, wherein the base electrode is made of a heavy metal. 3) The solid-state imaging device for radiation according to claim 1, wherein the photoconductor layer is made of Bi_1_2GeO_2_0. 4) The solid-state imaging device for radiation according to claim 1, wherein the scanning circuit section is constituted by a thin film transistor circuit.