JP2922098B2 - Semiconductor radiation detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a so-called array type semiconductor radiation detector in which a plurality of semiconductor portions as individual unit elements are arranged adjacent to each other.

[0002]

2. Description of the Related Art A semiconductor radiation detector measures a photocurrent generated in a semiconductor due to radiation with an electrode provided on the surface thereof. When a compound semiconductor such as CdTe or HgI ₂ is used, it can operate at room temperature due to a wide band gap, and has a large atomic number of a constituent element.
The absorption coefficient of X-ray and γ-ray is large, and high sensitivity can be obtained. In recent years, a plurality of semiconductor radiation detection parts are arranged adjacent to each other,
In order for a so-called array type semiconductor radiation detector to obtain a two-dimensional image or the like, application to medical diagnostic equipment, industrial non-destructive inspection equipment, and the like has attracted attention. In these applications, it is essential not only to improve the detection efficiency of each unit element constituting the array but also to improve the spatial position resolution in order to obtain highly accurate image information.

Conventionally, as a structure of such an array type detector, a unit element having electrodes provided on two opposing surfaces of a semiconductor is prepared, and then these unit elements are electrically separated by a predetermined space. And those arranged adjacent to each other are known. For example, a lead wire is connected to an electrode surface of a unit element, and the unit element is arranged at a predetermined interval.

[0004]

However, with the structure of the conventional array type detector, it is difficult to achieve high spatial position accuracy, and therefore, it is not possible to obtain high-accuracy image information. That is, since the mechanical accuracy in arranging the unit elements directly determines the spatial position resolution, it is impossible to obtain a spatial position resolution higher than the mechanical accuracy. In addition, the spatial resolution greatly varies depending on the connection state of the lead to the electrode. An object of the present invention is to provide a structure of an array-type semiconductor radiation detector in which excellent positional resolution can be obtained by a simple manufacturing process.

[0005]

According to the present invention, there is provided a semiconductor radiation detector comprising: an insulating plate provided with wiring patterns on both main surfaces; a plurality of substrates made of a radiation-sensitive compound semiconductor; A pair of electrodes formed so as to face each other on a plane substantially perpendicular to the incident surface, wherein the insulating plate is located between the bases, and the wiring pattern and the electrodes are in surface contact and electrically connected. Is what it is. In particular, compound semiconductors sensitive to radiation include CdTe, CdZnT
It is desirable to use a semiconductor containing CdTe as a main component such as e.

[0006]

According to the present invention, the respective substrates for detecting radiation are arranged in close contact with each other via the insulating plate, and the positional accuracy is substantially determined by the processing accuracy of the substrate and the insulating plate. At the same time, since the substrate is arranged in close contact and the radiation is incident from the surface on which the electrodes are not provided, the absorption length can be set independently of the drift length of the carrier, so that the sensitivity can be improved without sacrificing the carrier collection efficiency. In addition, since each electrode is in surface contact with the wiring pattern on the insulating plate, non-uniform force is not applied to the electrode and uniform detection characteristics can be obtained. Therefore, it is possible to obtain excellent positional resolution with a simple structure excellent in mass productivity.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A manufacturing process of an array type radiation detector according to an embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 1, a substrate 1 (thickness: 1 mm, 2 mm) made of chlorine-doped high-resistance CdTe semiconductor single crystal.
After polishing and etching both opposing main surfaces (0 mm square)
Platinum (Pt, thickness:
100 nm) is formed. The substrate 1 is cut into a 2 mm square by a cutting device (dicing saw) to produce five unit elements 4.

An alumina substrate 5 having a thickness of 0.2 mm is prepared as an insulating plate, and a gold-plated wiring pattern 6 is formed on both surfaces thereof. Four similar alumina substrates 5 are prepared. The wiring pattern 6 is brought into close contact with the surface of the electrode 2 of the unit element 4 and electrically and mechanically connected by a conductive adhesive (Ag epoxy). Further, another alumina substrate 5 'is similarly bonded to the other electrode 3 of the unit element 4. Similarly, five unit elements 4 and four alumina substrates 5 alternately combined with each other
Is fixed on the connection substrate 7 such that the surface of the unit element 4 on which the electrodes 2 and 3 are not provided faces the main surface.

The electrodes 2 and 3 of each unit element 4 are connected to signal extraction pins 8 provided on a connection substrate 7 via a wiring pattern 6 on an alumina substrate 5. The signal extraction pin 8 is connected to a bias power supply, a pulse height analyzer, and the like necessary for radiation measurement. The connection between the wiring pattern 6 and the signal extraction pin 8 is made of gold (A
u) The wire 9 is used, and a conductive adhesive (Ag epoxy) is used.
Are connected mechanically. The incident direction of the radiation is perpendicular to the connection substrate 7.

In the radiation detector manufactured in the above steps, the unit element arrangement accuracy is 0.1 mm or less, and the dark current of each element does not change before and after assembling into an array, and is 2 nA (bias voltage: 30 V). )Met.

The dimensions of the unit element in the present embodiment can be appropriately changed as the absorption length depending on the energy of the radiation to be detected, and the distance between the electrodes (the thickness of the substrate) depends on the applied voltage. Also, it can be appropriately changed depending on the characteristics of the CdTe crystal. Also, the number of unit elements to be arrayed can be set as needed.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a unit element used in a radiation detector according to an embodiment of the present invention.

FIG. 2 is a perspective view illustrating an insulating plate used for a radiation detector according to an embodiment of the present invention.

FIG. 3 is a perspective view illustrating a configuration of a radiation detector according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate (substrate made of a semiconductor) 2 One electrode 3 The other electrode 4 Unit element 5 Alumina substrate 6 Wiring pattern 7 Connection substrate 8 Signal extraction pin 9 Gold wire

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-53-101989 (JP, A) JP-A-56-110270 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 31/00-31/02 H01L 31/08 G01T 1/00-7/12

Claims (1)

(57) [Claims] 1. An insulating plate having a wiring pattern provided on both main surfaces, a plurality of substrates made of a radiation-sensitive compound semiconductor, and formed on a surface substantially perpendicular to a radiation incident surface of the substrate. A semiconductor radiation detector, comprising: a pair of electrodes, wherein the insulating plate is located between the bases, and the wiring pattern and the electrodes are surface-contacted and electrically connected.