JPH02244671A - Multi-element type photodetector and manufacture thereof - Google Patents

Abstract

PURPOSE:To enable crosstalk to hardly happen in a photosensor of this design by a method wherein adjacent pixel regions are completely isolated from each other through a gap. CONSTITUTION:Pixel regions 10, each of them is composed of a PN junction between semiconductor layers 3a and 3b, are formed on the surface of a board 1 protruding from it and arranged keeping a gap of prescribed length between them. An optical shielding layer 2 of metal foil is formed on the surface of the board 1 excluding the regions 10. A highly concentrated part 4 is formed on the layers 3a. When light rays impinge on a multi-element type photodetector formed as above, electrons generated in a depletion layer or a P-layer are hindered from flowing into an adjacent pixel region by the gap formed between the pixel regions. Even if light rays impinge on a gap between the pixel regions, electrons occurred nearly become extremely short in life time through the highly concentrated part 4, so that the occurrence of crosstalk becomes small in probability.

Description

[Detailed Description of the Invention] [Summary] The purpose of the present invention is to provide a multi-element type photo-sensing element that reduces the occurrence of cellulose talk and a method for manufacturing the same.
A plurality of pixel regions made of PN junctions made of HgCdTe, etc., protruding from the surface of the substrate and arranged with gaps of a predetermined length, and copper, silver, gold, etc. formed on the surface of the substrate excluding the pixel regions. The structure includes a light shielding layer made of a metal film, and a high concentration region formed on one semiconductor layer of the PN junction in contact with the light shielding layer. After forming a light-shielding layer made of a metal film, a semiconductor layer on the - side of the PN junction is formed in each pixel region using a liquid phase epitaxial method, and a PN junction is formed on the surface of the semiconductor layer. The high-concentration portion was configured to be formed using the metal of the light-shielding layer.

[Industry - Field of use of J2]

The present invention relates to a photodetecting element, and particularly to a multi-element type photodetecting element.

[Prior Art] FIG. 3 shows a cross-sectional view of a conventional photovoltaic infrared sensing element. CdTe, CdZnTe,.

Cd M n T e or Cd T e S e
A p-type semiconductor layer (hereinafter simply referred to as pi) 2 formed using a liquid phase epitaxial method or the like on a substrate 1 such as n° type semiconductor layer (hereinafter referred to as n゛ layer) 1 at predetermined intervals.
3 is formed by a method such as ion implantation, and a large number of pixel regions 20 in which PN junctions are formed are formed one-dimensionally or two-dimensionally.

[Problem to be solved by the invention]

The multi-element type photodetector made as above is 2
Since the layer 12 is common to each pixel region 20, the pixel region 20
Electrons e generated by light incident on p[12 between them may flow to the n' layer 13 in the adjacent pixel region. This phenomenon is called crosstalk, and is a cause of lower resolution.

On the other hand, in order to increase the resolution, each pixel area 20 is made smaller and more dense. There is a problem that 1" is not available.

The present invention has been proposed in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a multi-element type photodetecting element that further reduces the occurrence of crosstalk, and a method for manufacturing the same.

[Means to solve the problem]

To achieve the above object, as shown in FIG. It consists of a light-shielding layer 2 made of a metal film formed on the surface of the substrate except for the region 10, and a high concentration region 4 formed on one layer 3a of the PN junction in contact with the light-shielding layer 2.

As the substrate 1, CdTe, CdZr1Te, CdM
nTe, CdTeSe, and HgCdTc, HgZnTe, HgCd as the semiconductor layer forming the pixel region 10.
In addition to ZnTe, the light shielding layer 2 is made of copper, silver, or gold.

In addition, the above-mentioned multi-element type photodetecting element first has a substrate 1.
A plurality of pixel areas 1 on the surface. After forming the light shielding layer 2 made of a metal film except for the OS, one semiconductor N of the PN junction is formed in each pixel region 10s using a liquid phase epitaxial method.
3a, and then a PN junction is formed on the surface of the semiconductor layer 3a.

[For production]

Since adjacent pixel regions are completely separated by a gap, minority carriers generated in each pixel region 10 flow only to the corresponding pole of the eye region, making crosstalk less likely to occur.

〔Example〕

FIG. 1 is a process diagram showing the procedure for carrying out this invention.

First, as shown in Figure X(a), Cd Z n T e
pixel area forming portions (hereinafter referred to as pixel area portions) 10 provided at predetermined intervals (for example, 50 μm) on the substrate 1 of
A light shielding layer 2 is formed by vapor depositing Au (gold) using a mask. Next, as shown in No. 11'J (b), a p-type HgCdTe semiconductor layer (hereinafter referred to as p-layer ) 3a. At this time, since no epitaxial layer is formed on the Au portion of the light-shielding layer 2, the two layers 3a are formed only in the pixel region portion 10s with the predetermined thickness, and therefore each of the nine layers 3a is formed on the light-shielding layer 2. They will be arranged with a gap corresponding to the width of . After this, the nine layers 3a are heat-treated in a mercury atmosphere.
Adjust the impurity concentration (for example, about 10"/cd).

After the carrier concentration of the two layers 3a is adjusted, n"
Layer 3b is formed, and electrodes are further formed (not shown).

Note that during epitaxial growth, the impurity concentration is 101
If the composition of the melt material is selected so that the ratio is approximately b/ad, the above heat treatment step is unnecessary.

During the liquid phase epitaxial growth described above or during the heat treatment for adjusting the impurity concentration of the 9 layers 3a, the AU of the light shielding layer 2 partially thermally diffuses into the 9 layers 3a to form a high concentration part (91 parts) 4. The concentration portion 4 allows each two layers 3a and Au to be electrically continuous without any barrier.

When light (infrared rays) is incident on a multi-element photodetector element configured in this way, electrons generated in the depletion layer or two layers cannot flow to adjacent pixel regions due to the gaps formed between each pixel region. blocked. FIG. 2 is a diagram showing the structure of a sensing element when the gap between pixel regions is narrow, for example, about 5 μm.

When the interval between the pixel regions becomes narrower, the epitaxial growth layer also grows in the lateral direction, and the p-type semiconductor layer 3a is also stacked on the light shielding layer 2, so that the pixel regions are connected. In a portion of the p-type semiconductor layer in contact with the light shielding layer 2, a high concentration region 4 is formed by thermal diffusion of the light shielding film 2.

Therefore, as shown in FIG. 2, even if light enters between the pixel regions, the lifetime of electrons generated in the vicinity of the high concentration region 4 is extremely short, and the probability of crosstalk occurring is reduced.

In addition to CdZnTe, CdTe, Cd
TeSe, CdMnTe, etc. can be used, and as the metal deposited as the light shielding layer 2, besides Au, copper or silver can be used.

Note that if an antireflection film or a light absorption film is provided on the light shielding layer 2,
The amount of light reflected by the light shielding layer 2 is reduced, and resolution can be further improved.

〔Effect of the invention〕

As described above, the present invention has the effect that crosstalk is less likely to occur because each pixel region is separated by a gap.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing the procedure of the present invention, FIG. 2 is a diagram showing a detection element when the distance between pixel regions is narrow, and FIG. 3 is a schematic diagram showing a conventional method. In the figure, 1...substrate, 2...light shielding layer, 3 (3
a, 3b)...Semiconductor layer, 10...Pixel area, 10s...Pixel area portion. 4th fire of opening the value of insects ~ ・Axillary mulberry 1 壬 2nd figure atJ's Shiogyaga type #-li^ya search 壬情 3 figure

Claims (1)

[Scope of Claims] [1] A gap (
5), a plurality of pixel regions (10) made of PN junctions arranged while maintaining the same pixel regions (10), a light shielding layer (2) made of a metal film formed on the substrate surface excluding the pixel regions (10), and the light shielding layer ( 2) A multi-element type photodetecting element comprising a high concentration region (4) formed in one semiconductor layer (3a) of the above-mentioned PN junction in contact with the semiconductor layer (3a). [2] The above substrate (1) is made of CdTe, CdZnTe, Cd
MnTe, CdTeSe, and the semiconductor layer (3) constituting the pixel region (10) is HgCdTe, HgZnTe,
2. The multi-element type photodetecting element according to claim 1, wherein the metal forming the HgCdZnTe and the light shielding layer (2) is copper, silver or gold. [3] After forming a light-shielding layer (2) made of a metal film on the surface of the substrate (1) except for a plurality of pixel regions (10s), each pixel region (10s) is coated using a liquid phase epitaxial method. 1. A method of manufacturing a photodetecting element, characterized in that one semiconductor layer (3a) of a PN junction is formed, and a PN junction is formed on the surface thereof.