JPS604597B2 - Manufacturing method of infrared sensing element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an infrared sensing element using a multi-component semiconductor.

Ternary alloy semiconductors containing mercury, such as H&-xCdxTe
Because it has a narrow energy gap, it is used as a material for infrared sensing elements.

In the process of manufacturing this infrared sensing element, the purpose is to prevent the light-receiving surface of the element from immediately coming into contact with the outside air and forming an unstable layer due to moisture in the outside air, or to prevent total reflection of incident infrared rays. Conventionally, zinc sulfide (ZnS) or the like is deposited on the light-receiving surface of an infrared sensing element to form a protective film. However, the protective film formed by vapor deposition of Z resin is
It has poor adhesion to materials such as rudder Te, and has the drawback of peeling or cracking during use of the element.

Further, there were also problems such as the time required for vapor deposition of ZnS and the process of forming the element becoming longer. The present invention solves the above-mentioned problems, and when manufacturing an infrared sensing element made of a multi-component semiconductor, after performing the necessary processing to form an infrared sensing element on a multi-component semiconductor substrate, acetamide is mainly used. It is an object of the present invention to provide a novel method for manufacturing an infrared sensing element, which comprises anodic oxidizing the above-mentioned substrate in a bath containing a component to form a surface protective film on the light-receiving surface of the sensing element.

An embodiment of the present invention will be described in detail below with reference to the drawings.

Figures 1 to 6 show the process for simultaneously manufacturing two infrared sensing elements on a silicon support plate, and Figures 7 onwards show the manufacturing process after each element is separated into one infrared sensing element unit. FIG.

Incidentally, the case where two or more elements are simultaneously formed on the support slope can be realized by the same process. The following will be explained in sequence according to the drawings. As shown in Fig. 1, the 91XCdxTe wafer 1, which has been subjected to necessary surface treatments such as polishing and etching, is bonded to a high resistivity sapphire support plate 3 using an epoxy adhesive 2, and then polished. to make a thin layer. Next, as shown in Fig. 2, the photoresist film 4 is
- Apply onto the real dxTe wafer. Next, as shown in Figure 3, Hg, -xC and Te
The photoresist film at the portion of the wafer (hereinafter simply referred to as wafer) to be etched is removed. Thereafter, the wafer 1 is etched to a predetermined size using an etching solution prepared by diluting simple bromine (Br2) with methyl alcohol (CH30H). After that, the photoresist film on the wafer is removed. Next, the X and Y portions of the adhesive 2 exposed under the wafer in FIG. 3 are removed using a removing agent such as concentrated sulfuric acid to expose the surface of the Si support plate 3 as shown in FIG. Through the above process, the wafer is separated into rectangular shapes that are similar in size to the device forming dimensions, and then, as shown in Figure 5, the wafer is etched to the dimensions required for the final device shape using photolithography technology. do. A plan view of FIG. 5 is shown in FIG. 6. After doing this, the sapphire support plate is cut at the dotted line 1 in FIGS. 5 and 6 in order to separate each element. Next, as shown in Fig. 7 and Fig. 8, metal indium (ln) was added using a metal mask or the like on the electrode forming part AB of the element made of Hg, 1xCdxTe, which was separately molded as one infrared sensing element. A vapor deposition layer 5 is formed. Next, a photoresist film is applied to areas other than the light-receiving surface C shown in FIGS. 7 and 8, and the photoresist film is immersed in an anodizing bath to anodize the light-receiving surface C for about 1 minute. The case for anodic oxidation is mainly composed of N-methylacetamide, and the composition is N-methylacetamide (CH3C○・NQ) 2: ethylene glycol (CH20 days・C ratio OH) 4: water (days) 2
0) Add ammonia water (NH40H) and oxalic acid (
Add a buffer consisting of COO/COOH) to adjust the pH to 6.
It was kept at ~8. According to experiments conducted by the present inventors, when the pH value becomes more acidic or alkaline than the above, the anodic oxide film produced becomes porous and the quality of the film deteriorates. However, when it is carried out within the above-mentioned approximately neutral pH range, a glass-like anodic oxide film of good quality is formed. In this way, as shown in FIGS. 9 and 10, an anodic oxide film 6 of Hg, -xCdxTe is formed on the light-receiving surface of the Hg, -xCdxTe element. Thereafter, the photoresist film deposited on areas other than the light-receiving surface is removed to complete the infrared sensing element. The oxide protective film formed by such anodic oxidation method has better adhesion to the element than the protective film formed by ZnS vapor deposition, and phenomena such as peeling and cracking do not occur during use of the element. .
In addition, in the case of forming a protective film by vapor deposition, the process time is approximately 2
Although it takes time, in the case of forming a protective film by the anodic oxidation method of the present invention, the time is significantly shortened to about 10 minutes. Also HQ-
When forming an xCdxTe element, it is necessary to reduce the influence of heat as much as possible since Hg is particularly easily evaporated by heat.

When forming a ZnS protective film by vapor deposition, the element is heated to some extent by the heater of the vapor deposition layer. However, when the protective film is formed using an anodic oxidation method, there is no risk that the element will be affected by heat. The anodic oxide film thus formed also has the effect of acting as an antireflection film against incident infrared light. Although the above embodiments have been described using a ternary alloy semiconductor containing mercury as an example, the present invention can also be used when manufacturing an infrared sensing element from other alloy semiconductors containing lead.

As described above, when an infrared sensing element is manufactured using an alloy semiconductor of Hg or Pb, if the anodic oxide film of the material forming the element is used as a protective film against the outside air on the light-receiving surface of the sensing element, conventional It has better adhesion to the element than the protective film formed by the vapor deposition method described above, and phenomena such as peeling and cracking do not occur during use of the element, improving the reliability of the infrared sensing element.

Furthermore, in the process of forming the element, there is less influence from heat than when forming a protective film by vapor deposition, so a highly reliable infrared sensing element can be obtained. Furthermore, since the anodic oxide film also has an effect as an anti-reflection film against infrared light, the light-receiving efficiency of the infrared sensing element is also improved by coating the anodic oxide film of the element forming material on the light-receiving surface.

[Brief explanation of the drawing]

1 to 10 are a sectional view and a plan view for explaining the manufacturing process of an infrared sensing element according to the present invention. 1: Hg, 1xC Te substrate, 2: Adhesive, 3: Sapphire support plate, 4: Photoresist film 5: Deposited film for electrode formation 6: Anodic oxide film, A, B: Electrode forming part, C :
Light-receiving surface, 1: Cutting position, X, Y: Exposed part of adhesive. Figure - Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 - Figure 0

Claims (1)

[Claims] 1. When manufacturing an infrared sensing element made of a multi-component semiconductor, after performing the necessary processing to form an infrared detecting element on a multi-component semiconductor substrate, the substrate is anodized in a bath containing acetamide as a main component. . A method of manufacturing an infrared sensing element, comprising: forming a surface protective film on the light receiving surface of the infrared sensing element.