JPS6035834B2 - Semiconductor device for radiation detection - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a semiconductor device for detecting radiation radiation, which is used to electrically detect radiation radiation such as light, X-rays, y-rays, charged particles, and nuclear fission fragments.

Conventionally, as such a semiconductor device for detecting beam radiation, the first
As shown in the figure, an N-type semiconductor region 3 is formed in a semiconductor substrate 1 made of, for example, P-type germanium from the main surface 2 side.
is formed to form a PN junction 4, and on the other hand, a thin protective layer 5 made of, for example, Si02 is formed on the main surface 2 of the semiconductor substrate 1. , an annular window 6 is pierced, and an annular electrode 7 is ohmically attached to the semiconductor region 3 through the window 6, and another main surface facing the main surface 2 of the semiconductor substrate 1 8 has been proposed in which an electrode 9 is ohmically attached.

Further, as shown in FIG. 2, in which parts corresponding to those in FIG. A semiconductor region 3 is formed to form a PN junction 4, and an N-type semiconductor region 10 similarly forms a PN junction 11 in the semiconductor substrate 1 from the main surface 2 side. With a depth greater than that of the semiconductor region 3, so as to connect and surround the semiconductor region 3 from the outside,
On the other hand, a thin protective layer 5 made of Si02, for example, is formed on the main surface 2 of the semiconductor substrate 1, and a semiconductor region 1, for example, is formed in an annular shape as a so-called guard ring.
An annular window 6 is formed at a position above the semiconductor region 10', and an annular electrode 7 is ohmically attached to the semiconductor region 10' through the window 6, and also faces the main surface 2 of the semiconductor substrate 1. Another structure has been proposed in which an electrode 9 is attached to an ohmik on another main surface 8.

Further, as shown in FIG. 3, in which parts corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals, Si
02 is formed, a relatively large window 6 is formed in the protective layer 5, and a Schottky junction is formed between the main surface 2 of the semiconductor substrate 1 and the semiconductor substrate 1. A metal layer 12 that also serves as an electrode made of a metal that can be formed is formed to form a Schottky junction 13, while an electrode is formed on the other main surface 8 facing the main surface 2 of the semiconductor substrate 1. A structure in which 9 is attached to ohmic has also been proposed.

Incidentally, in the case of the semiconductor device for detecting beam radiation shown in FIGS. 1 and 2, a load 15 is connected between the electrode 7 and the ground, and a bias power source is connected between the electrode 9 and the ground with the electrode 9 side being negative. 16 to apply a predetermined operational reverse bias voltage to the PN junction 4 in the case of FIG. 1 and to the PN junctions 4 and 11 in the case of FIG. If P
Spreading out from N junction 4, in the case of Fig. 2, PN junctions 4 and 1
1, and in the case of the semiconductor device for detecting beam radiation shown in FIG. 3, the metal layer 12 is used as an electrode.
A load 15 is connected between it and the ground, and a bias power supply 16 with the electrode 9 side being negative is connected between the electrode 9 and the ground as in the case of FIGS. 1 and 2, and the Schottky junction 13 gives a reverse bias power supply for a given operation, and then
A depletion layer 17 extending from the Schottky junction 13 from the side is obtained in the semiconductor substrate 1, and with the depletion layer 17 obtained in this way, the beam detection shown in FIGS. 1, 2, and 3 is performed. In any case of a semiconductor device for use in semiconductor devices, if a lateral ray is incident on the main surface 2 side of the semiconductor substrate 1 into the depletion layer 17 obtained as described above, the lateral ray will be incident on the load 15. It can supply power according to the amount.

Therefore, the semiconductor device for ray detection shown in FIGS. 1, 2, and 3 functions as a ray detection device.

However, in any case of the semiconductor device for ray detection shown in FIGS. 1, 2, and 3, the depletion layer 17 obtained as described above on the main surface 2 of the semiconductor substrate 1 Carriers generated on the main surface side of the semiconductor substrate 1 from the surface level of the region A facing
is P type, so electrons) reach the semiconductor layer 3 in the case of FIG. 1, the semiconductor layer 3 via the semiconductor layer 10 in the case of FIG. 2, and the metal layer 12 in the case of FIG. Similarly, from the current component and the surface level of region b on the main surface 2 of the semiconductor substrate 1, from the outer edge of region A where the depletion layer 17 faces to the distance corresponding to the carrier diffusion distance, Similar carriers generated on the main surface side of the semiconductor substrate 1 are generated by diffusing to the depletion layer 17, and the carriers pass through the depletion layer 17, as described above, in FIGS. In the case of Fig. 2, the semiconductor layer 3, in the case of Fig. 3, the metal layer 1.
2, a surface leakage current consisting of a carrier diffusion current component flows to the load 15 as a fat current,
However, it was something that could not be ignored.

This is especially true when the semiconductor substrate 1 is made of germanium, since its surface condition is generally relatively unstable.

Furthermore, in order to reduce the overall size, if the area of the PN junction 4 in FIGS. 1 and 2 is made small, and the area of the Schottky junction 13 in FIG. This is especially the case since the ratio of the current to the current depending on the amount of incident beams obtained on the load 15 becomes large.

Therefore, although the present invention is based on the semiconductor device for detecting beam radiation described above in FIGS. 1, 2, and 3, the surface leakage current as a part of the floor current is negligible. This will become clear from the detailed description below.

4, 5, and 6 show a semiconductor device for ray detection according to the present invention, which is based on the conventional semiconductor device for ray detection described above in FIGS. 1, 2, and 3, respectively. An embodiment of the apparatus is shown, and parts corresponding to those in FIGS. 1, 2, and 3 are given the same reference numerals, but in the case of FIG. 4,
In the semiconductor substrate 1, from the main surface 2 side, an N-type semiconductor region 20 having the same conductivity type as the semiconductor region 3 forms a PN junction 21, and the semiconductor region 3 is not connected thereto. It has the same configuration as in FIG. 1 except that it is formed so as to surround it from the outside.

In addition, in the case of FIG. 5, an N-type semiconductor region 20 is formed in the semiconductor substrate from the main surface 2 side, similar to the case of FIG.
In the case of FIG. 2, except that the semiconductor region 3 is formed with the semiconductor region 10 so as to form a PN junction 21 and to surround it from the outside without being connected to the semiconductor regions 3 and 10. It has a similar configuration.

Furthermore, in the case of FIG. 6, the metal layer 22 made of a metal capable of forming a Schottky junction with the semiconductor substrate 1 is formed on the main surface 2 of the semiconductor substrate 1 so as to form a Schottky junction 23, and the metal layer 12 is It has the same structure as that shown in FIG. 3, except that it is surrounded from the outside without being connected to it.

However, in the case of FIGS. 4 and 5, a window 24 is provided in the insulating layer 5 to expose the semiconductor region 20 to the outside, and an electrode 25 is attached to the semiconductor region 20 through the window 24. .

The above is the configuration of the embodiment of the semiconductor device for ray detection according to the present invention, which is based on the conventional semiconductor device for ray detection described above in FIGS. 1, 2, and 3.

According to the semiconductor device for ray detection according to the present invention having the configuration described above in FIGS. 4, 5, and 6,
Since they have the same configuration as the conventional semiconductor device for beam detection shown in FIGS. 1, 2, and 3, except for the matters mentioned above, FIGS. In the case of the semiconductor device for ray detection shown in FIG. In addition, a bias power supply 1 is provided between the electrode 9 and the ground, with the electrode 9 side being negative.
6 and apply a predetermined operating reverse bias voltage to the PN junction 4 in the case of FIG. 4 and to the PN junctions 4 and 11 in the case of FIG. If P
From the N junction 4, a depletion layer 17 extending from the PN junctions 4 and 11 in the case of FIG. 5 is obtained, and in the case of the semiconductor device for beam detection shown in FIG. As in the case of the semiconductor device for radiation detection, a load 15 is connected between the metal layer 12 and the ground, and a bias power source 16 with the electrode 9 side being negative is connected between the electrode 9 and the ground to form a Schottky junction. 13 is applied with a predetermined operating reverse bias voltage, a depletion layer 17 extending from the Schottky junction 13 is obtained in the semiconductor substrate 1, and with the depletion layer 17 obtained in this manner, FIG. In either case of FIG. 5 or FIG. It is possible to supply a current according to the amount of incident light.

Therefore, in the case of the semiconductor device for lateral ray detection according to the present invention shown in FIGS. 4, 5, and 6, the conventional lateral ray detection semiconductor device shown in FIGS. As in the case of a semiconductor device, it functions as a ray detection device.

However, in the case of the semiconductor device for width ray detection according to the present invention shown in FIGS. 4, 5, and 6,
In the case of the figure, there is a semiconductor layer 20 forming a PN junction 21 and an electrode 25 attached thereto ohmically, whereas in the case of FIG. If a resistor 26 is connected between the electrode 25 and the ground in the case of FIGS. 4 and 5, and between the metal layer 22 and the ground in the case of FIG.
1, since the same reverse bias voltage as the operating reverse bias voltage mentioned above is applied to the Schottky junction 23 in the case of FIG. 6, the voltage between the semiconductor regions 3 and 20 in the case of FIG. 20, in the case of FIG. 6 the metal layer 12
By appropriately selecting the distance between P and 22, the depletion layer 27 formed in the semiconductor substrate 1 and connected to the depletion layer 17 obtained as described above is formed in the case of P in FIGS. 4 and 5.
It is obtained by extending from the N junction 21 or, in the case of FIG. 6, from the Schottky junction 23.

Moreover, if the depletion layer 27 is obtained in this way, 'a} In the case of FIG. 6 of the semiconductor region 20 of FIGS. 4 and 5, where the depletion layer 27 faces the main surface 2 of the semiconductor substrate 1, Carriers generated from the surface level of the region A' outside the outer edge position of the Schottky junction 23 reach the semiconductor region 20' in the case of FIGS. 4 and 5, and the metal layer 22 in the case of FIG. 'b} The carriers generated from the surface level of the region 8 on the main surface 2 of the semiconductor substrate 1 between the outer edge position of the region A' and the position corresponding to the carrier diffusion distance are , which are generated by diffusion to the depletion layer 27, and the carriers pass through the depletion layer 27 to the semiconductor region 2 in the case of FIGS. 4 and 6, and to the metal layer 22 in the case of FIG. The carrier diffusion current component due to reaching {c} on the main surface 2 of the semiconductor substrate 1, between the semiconductor regions 3 and 20 in the case of FIG. 4, between the semiconductor regions 10 and 20 in the case of FIG. In the case of FIG. 4, the carriers generated from the surface level of the region C between the Schottky junctions 13 and 23 are
A surface leakage current is generated in the semiconductor regions 3, 10, and 20 in the case of FIG. 5, and consists of a carrier current component due to reaching the metal layers 12 and 22 in the case of FIG.

However, in this case, since a potential barrier is formed in the region below region C of semiconductor substrate 1, almost all of the carrier current component based on carriers generated from surface leakage in region C in the surface leakage current is Half of the carriers, which become the current component, reach the semiconductor region 3 in the case of FIG. 4, the semiconductor regions 3 and 10' in the case of FIG. 5, and the metal layer 12 in the case of FIG. In the case of FIG. 5, the electrode 7 is
In the case of the figure, even though it flows through the metal layer 12 to the load 15, the other half of the carrier current component blocks the carriers generated from the surface level of region C, and the other half of the carrier current component is generated from the surface level of region A'. The carrier current component that blocks the carriers generated from the surface level of region B' and the carrier diffusion current component that blocks the carriers generated from the surface level of region B' are the carrier current components that block the carriers generated from the surface level of region B'. , in the semiconductor regions 3 and 10 in the case of FIG. 5, and in the metal layer 12 in the case of FIG. is absorbed and therefore does not flow through the electrode 7 in the case of FIGS. 4 and 5, through the metal layer 12 in the case of FIG. 6, and through the electrode 25 in the case of FIGS. It flows through the metal layer to resistor 26.

Therefore, the carrier current component flowing through the load 15, which blocks the carriers generated from the surface states of the region C, is as shown in FIGS.
This corresponds to the carrier current component generated from the surface level of region A in the conventional case described above in FIG.

Therefore, according to the semiconductor device for detecting beam radiation according to the present invention described above with reference to FIGS. It has the following characteristics.

Incidentally, in the case of the conventional semiconductor device for detecting beam radiation as described above in FIGS. 1 to 3, if the surface leakage current as a part of the floor current is 0.25 A, the In the case of the semiconductor device for detecting beam radiation according to the present invention described above in FIG. 6, the surface leakage current as a part of the floor current was 0.04 French A. Incidentally, although the structure is apparently similar to that of the semiconductor device for detecting rays of radiation according to the present invention described above in FIG.
When the same reverse bias voltage as the operating reverse bias voltage applied to the electrodes 9 and 7 is applied between the electrodes 9 and 7, a depletion layer 27 is obtained by expanding from the PN junction 21 in the semiconductor substrate 1.
In the case of a semiconductor device for beam detection not according to the present invention in which the depletion layer 17 obtained by expanding from the N junctions 4 and 11 is maintained at a large distance so that it cannot be obtained by being connected, the depletion layer of the semiconductor substrate 1 As a part of the carrier current component generated from the surface semi-conductor in the region between 17 and 27 is absorbed by the semiconductor region 20, the surface leakage current is reduced by that much compared to the case where the semiconductor region 20 is not provided. Also, since the carrier current component generated from the surface level of the region of the semiconductor substrate 1 where the depletion layer 17 is formed is hardly absorbed by the semiconductor region 20, the surface leakage current is as shown in FIGS. This does not become negligible as in the case of the semiconductor device for ray detection according to the present invention described above with reference to FIG.

Note that the above description has only shown a few examples of the present invention, and in the configuration described above in FIGS. 4 and 5, the configuration of the semiconductor region 20 and the electrode 25 attached thereto is as follows.
The configuration of the metal layer 22 in the configuration described above in FIG. 6 is replaced with the configuration of the metal layer 22 in the configuration described above in FIG. The configuration of the region 20 and the electrode 25 attached thereto may be replaced, and various other modifications and changes may be made without departing from the spirit of the present invention.

[Brief explanation of the drawing]

FIG. 1, FIG. 2, and FIG. 3 are schematic cross-sectional views each showing a conventional semiconductor device for detecting beam radiation. FIG. 4, FIG. 5, and FIG. 6 are schematic cross-sectional views each showing an embodiment of a semiconductor device for detecting beam radiation according to the present invention. 1...Semiconductor substrate, 2...Main surface,
3, 20... Semiconductor region, 4, 11, 21...
PN junction, 7, 9, 25... electrode, 12, 22...
Metal layer, 13, 23... Schottky acid synthesis. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] 1 A semiconductor substrate having a first conductivity type and having a first electrode attached thereto has a second conductivity type opposite to the first conductivity type from both main sides of the semiconductor substrate and a second electrode having a second conductivity type opposite to the first conductivity type. A first semiconductor region attached thereto forms a first PN junction, or a first metal layer doubling as the second electrode on the main surface of the semiconductor substrate forms a first shot junction. In the semiconductor device for detecting radial rays, the first beam is inserted into the semiconductor substrate from the main surface side thereof.
A second semiconductor region having the same second conductivity type as the semiconductor region and to which a third electrode is attached forms a second PN junction, or on the main surface of the semiconductor substrate. A second metal layer, which also serves as a third electrode, surrounds the first semiconductor region or the first metal layer from the outside so as to form a second shot junction without being connected thereto. The second semiconductor region or the second metal layer is formed between the first and third electrodes with respect to the first semiconductor region or the first metal layer. and a second PN junction obtained by expanding from the second PN junction or the second Schottky junction into the semiconductor substrate when the same reverse bias voltage as the operating reverse bias voltage is applied between the second electrodes. The depletion layer is the first PN
1. A semiconductor device for detecting beam radiation, characterized in that the semiconductor device maintains a distance sufficient to be connected to a first depletion layer obtained by expanding from a junction or the first shot junction.