JPH0220850Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a semiconductor radiation detector, and particularly improves the structure of the joint of the detection element.

As is well known, semiconductor radiation detectors use a PN junction type or metal/semiconductor junction type shotgun barrier diode structure as a detection element.
It applies a reverse bias to the PN junction or metal/semiconductor junction and detects the current generated by the incident radiation. By the way, when the incident radiation is radiation that has low material penetration, such as beta rays, in a detector in which the detection element is mounted in the case, the radiation is absorbed by the case, resulting in a significant decrease in sensitivity, making it impractical for practical use. It becomes impossible to provide. For example, the range of β-rays (the distance at which they collide with a substance and stop without losing kinetic energy) is in the case of silicon and iron (Fe).
Since the diameter of a 100KeV beta ray is approximately 20μm and 70μm, it is not possible to mount a detection element in a case made of iron. Therefore, at present, semiconductor detectors are used without a case. On the other hand, semiconductor detectors are generally very sensitive to moisture, dirt, gas, etc., and therefore must be used for measurements and stored with great care in a very clean atmosphere, and are difficult to handle. This was extremely troublesome and also caused problems in terms of reliability.

Therefore, an object of the present invention is to provide a semiconductor radiation detector that is extremely easy to handle and highly reliable.

Another object of the present invention is to provide a semiconductor radiation detector suitable for detecting radiation having low material penetration, such as β-rays.

The purpose of the present invention is to create a PN junction diode structure in which an N-type (P-type) layer is formed on a P-type (N-type) semiconductor substrate, or a shot barrier type diode structure in which a barrier metal is bonded to a P-type (N-type) semiconductor substrate. In a semiconductor radiation detector using a semiconductor radiation detector as a detection element, the structure of the junction of the detection element is the semiconductor substrate-metal-SiO ₂ film or Si ₃ N ₄ film structure, and the junction is made with a part of the structure remaining. This is achieved by the semiconductor radiation detector of the present invention whose other parts including the end portion are covered with resin.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows PN used in semiconductor radiation detectors.
An example of a detection element having a junction diode structure is shown.
This detection element 1 is, for example, silicon N ⁺ type (P ⁺
It has a PN junction diode structure in which an N-type (P-type) layer 3 is formed on a substrate 2 and a P-type (N-type) layer 4 is formed by diffusing P-type (N-type) impurities into an N-type semiconductor substrate. . Usually, an electrode (not shown) made of metal such as aluminum or gold is deposited on the P type (N type) layer 4, and a negative voltage (positive voltage) is applied to this electrode, and the N ⁺ type substrate 2 is grounded. or positive voltage (negative voltage)
is applied to reverse bias the PN junction and measure the radiation.

The sensitive area A of the detection element 1 having such a configuration is the area where the depletion layer 5 is formed, and the region 6 where the formed depletion layer 5 contacts the surface of the detection element 1 is sensitive to the atmosphere. Therefore, it is important to minimize the influence of environmental conditions on the radiation sensitive region A and to avoid placing unnecessary substances on the surface of the detection element as much as possible, and to shield the region 6, which is easily affected by the atmosphere, from the atmosphere. There is a need.

Therefore, in the present invention, the junction part of the detection element, that is, the sensitive area, is made of a semiconductor substrate-metal-SiO ₂ film or Si ₃ N ₄ film structure, and the atmosphere-sensitive area is made of a molding material. This is a protected configuration. That is, as shown in one embodiment in FIG. 2, a metal layer 8 of aluminum, gold, etc. is formed on a P-type (N-type) layer 4 formed by selective diffusion using an oxide film 7, for example, by vapor deposition and selective etching. on which an insulating film 9 of SiO ₂ or Si ₃ N ₄ is formed.
A window is formed in a part of the layer 8 by, for example, the CVD method, and a lead wire 10 is bonded to the layer 8.

FIG. 3 is a perspective view of a detector completed by molding this element 1 with resin 11. A pair of external terminals 12 and 13 connected to the substrate 2 and leads 10 (FIG. 2) protrude. resin 10
has a window 14 in the center of its upper surface that reaches the surface of the sealed element 1.

In this way, in this invention, the main part of the sensitive area is covered only with a very thin metal layer and an insulating layer, so the absorption of radiation is extremely small, and the environmental resistance is good. Sensitive areas are molded with resin and are completely isolated from the surrounding atmosphere. Therefore, it is possible to reliably detect radiation such as β-rays that have low material penetration, and it is also easier to handle, and storage is easier than storing it in a dry _N2 atmosphere as in the past. Since this is not necessary, there are excellent advantages such as easy storage and improved reliability.

In the above embodiment, the present invention was applied to a radiation detector using a PN junction diode structure as a detection element, but the invention can also be applied to a radiation detector using a Schottky barrier diode structure as a detection element. It goes without saying that similar effects can be obtained. Further, the opposite conductivity type shown in parentheses may be used, or a semiconductor other than silicon may be used. Also, the metal of the metal layer is gold (An).
In this case, the insulating film (SiO ₂ , Si ₃ N ₄ ) may be omitted. Furthermore, the shape, structure, etc. of the detection element are not limited to the illustrated example.

As mentioned above, according to the present invention, it is easy to handle and store like ordinary semiconductor devices, and
Because we can obtain a highly sensitive semiconductor radiation detector that can detect radiation that has low penetration through materials, such as lines,
It has great practical value when applied to various radiation detection devices.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing an example of a detection element used in a semiconductor radiation detector, Fig. 2 is a sectional view of a semiconductor radiation detection element according to the present invention, and Fig. 3 shows the element in Fig. 2 molded with resin. FIG. 1...Detection element, 3...N type (P type) layer, 4...
... P type (N type) layer, 6... Atmosphere sensitive area,
A...Sensitive area of detection element, 8...Metal layer, 9...
...Insulating film, 11...Mold resin.

Claims (1)

[Scope of utility model registration request] A PN junction diode structure in which an N-type (P-type layer) is formed on a P-type (N-type) semiconductor substrate and an ohmic electrode is provided on this layer, or a shot switch in which a barrier metal is bonded to a P-type (N-type) semiconductor substrate. In a semiconductor radiation detector that uses a barrier diode structure as a detection element, a SiO ₂ film or a Si ₃ N ₄ film is provided on the electrode or metal, and a part of the film is left and other parts including the end of the junction are covered. A semiconductor radiation detector characterized by being covered with resin.