JPS6290981A - Manufacture of infrared detecting element - Google Patents

Abstract

PURPOSE:To manufacture an element without contacting an anodic oxidation film with medicine by forming a specific groove on an infrared detecting element wafer, then forming a metal deposited film, and subjecting to an anodic oxidation with the film as a mask to form the first protective film. CONSTITUTION:A compound semiconductor 2 is formed on a high resistance substrate 1, and a wafer 7 is formed. Then, the wafer 7 is etched to arrive at the substrate 1 or to form a groove 13 of shape deeper than the substrate. Then, a metal deposited film 14 is formed on the wafer 7. Then, the wafer 7 is subjected to a plasma anodic oxidation to form an anodic oxidation film 8 to become the first protective film 4. A ZnS film 9 is formed on the entire surface of the wafer 7. Then, the semiconductor 2 is exposed to form an electrode hole 10 and an element dividing line 12. Subsequently, an electrode 6 is formed, the wafer 7 is eventually cut along the dividing line 12 of the element, and an infrared detecting element is formed. Since the element can be formed without contacting the anodic oxidation film with medicine, the yield of the element is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method of manufacturing an infrared sensing element using the phenomenon of light guide 1.

[Conventional technology]

FIG. 4 is a plan view showing the structure of a conventional light guide "ttm" infrared sensing element, and FIG. 5 is a sectional view thereof.

In these figures, 1 is a high-resistance substrate, 2 is, for example, H
A compound semiconductor such as gCdTe; 3 is a light-receiving surface; 4 is a light-receiving surface 3 formed by an anodic oxide film of the compound semiconductor 2;
5 is a second protective film of the light-receiving surface 3 made of, for example, ZnS, and 6 is an electrode made of, for example, In.

Next, a method for manufacturing a conventional photoconductive infrared sensing element will be explained using FIGS. 6(a), 6(b), and 6(c).

First, a high-resistance compound semiconductor 2 such as 4KHgCdTe is formed to a predetermined thickness by a method such as epitaxial growth, and an infrared sensing element wafer (hereinafter simply referred to as wafer) 7 is fabricated.

Next, an anodic oxide film 8 that will become the first protective film 4 is formed over the entire surface of the wafer 7 by, for example, plasma anodic oxidation.

Plasma anodic oxidation is a method in which a sample is inserted into oxygen plasma generated by high-frequency discharge, and a positive voltage is applied to the sample with respect to other electrodes in the plasma to perform anodic oxidation.

Next, ZnS@9, which will become the second protective film 5, is formed on the entire surface of the anodic oxide film 8 by a method such as sputtering.

Subsequently, the anodic oxidation m8 and a part of the ZnS film 9 are etched using a photolithography method to open an electrode hole 10 as shown in FIG. 6 and expose the compound semiconductor 2.

Next, use a metal mask etc. to select the material that will become the electrode.

For example, place the erotic m11 on the light receiving surface 3 as shown in FIG. 6(b).
is deposited on the area excluding the area where it is planned to be formed.

After that, according to the shape of the element to be manufactured, In111゜Z
nS film9. Anodic oxidation 1118. 201 parts of the compound semi-enveloped body is etched using a photolithography method until it gets lost in the high-resistance substrate 1, thereby forming the dividing line 12 of the element as shown in FIG. 6(c).

Divide the element using the final trap, dicing, etc. & t1
The infrared sensing element as shown in FIG. 4 was manufactured by cutting into individual elements along the lines shown in FIG.

[Problem that the invention seeks to solve]

However, in the above five conventional methods, cracks occur in the first protective film 4 and the second protective film 5 when forming the electrode holes 10 and the parting lines 12 of the element, making it difficult to manufacture an infrared sensing element. The problem was that it was difficult. This is Hg
The Cd Te anodic oxide film 8 is very weak to chemicals.
- Because the resist is a film, the side etching does not stop within a short range, and the problem arises because the etching solution penetrates into the anodic oxide film K below the resist.

This invention was made to solve the above-mentioned problems, and the first protective film, which is an anodic oxide film, can be exposed to infrared rays without coming into contact with chemicals such as resist or etching solution in subsequent steps. It is an object of the present invention to provide a method for manufacturing a sensing element.

[Means for solving problems]

The method for manufacturing an infrared sensing element according to the present invention includes forming a groove on an infrared sensing element wafer that surrounds a light receiving surface and at least one electrode and has a depth that reaches or is deeper than a high-resistance substrate; Forming a metal vapor deposited film in a predetermined shape,
The first protective film is formed by anodizing the infrared sensing element Uni-Hachi using the gold-S vaporized film as a mask, and then the second protective film is formed to cover the first protective film. be.

[Effect]

In this @ Ming, due to the action of the groove and gold Js evaporation layer exchange,
Since the anodic oxide film, which is the first protective film, is selectively formed, the anodic oxide film is not exposed to chemicals such as etching solution in subsequent steps, and the electrode holes can be completely sealed.

Parting lines for elements can be formed.

〔Example〕

FIG. 1 is a plan view showing the structure of a four-electrode infrared sensing element showing an embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3(a), (b), (C ) is a diagram showing the manufacturing process of the infrared sensing element according to the present invention.

In these figures, 1 to 10.12 are the same as shown in FIGS. 4 to 6, 13 is a U-shaped groove, and 14 is a metal heat-4M. The U-shaped groove 13 is formed to surround a region where the light-receiving surface 3 is to be formed and a region where one of the electrodes 6 is to be formed.

The method for manufacturing an infrared sensing element according to the present invention will be described below with reference to FIG.

First, as in the conventional example, Hg is placed on a high-resistance substrate 1.
A wafer γ is manufactured by forming a compound half-layer body 2 made of CdTe or the like to a predetermined thickness by a method such as epitaxial growth.

Next, the sea urchin 8 is etched using the 446 plate method to form a U-shaped groove 13 as shown in Fig. 3(a).Groove 1
3 shall be dug to reach the high resistance substrate 1 or deeper than it.

Next, the sea urchin 7 is exposed to plasma in the same way as in the conventional example. Anodic oxidation is performed to form an anodized film 8 that will become the first insulator 111i14.

At this time, the metal vapor deposited film 14 serves as a mask, so as shown in FIG.
Only on the exposed part of the metal vapor deposited film 14 in b),
Anodic oxidation PA8 of the compound semiconductor 2 is formed.

In the initial stage of anodic oxidation, the anode current mainly flows through the metal vapor deposited film 14 having low resistance, and the compound semiconductor 2 is hardly anodized. However, if a metal that is easily oxidized like In in this example is used, an insulating oxide film is formed on the surface and the anodic oxidation direct current flows through the compound semiconductor 2.
8 can be easily formed.

Furthermore, even if the metal vapor deposited film 14 is completely cultivated, the anodic oxidation flow traces back the compound semiconductor 2 under the metal vapor deposition film 14 and reaches the electrode of the plasma anodization device, so that the anodic oxide film 8 is formed. There is no problem.

As described above, using the metal island 7f film 14 as a mask, the first protection i[! After selectively forming the anodic oxide film 8 that will become the i film 4, a ZnS film 9 that will become the second protective pA 5 is formed over the entire surface of the wafer 7 by sputtering.

Next, as shown in Fig. 3<C) using photolithography, Zn
The S film 9 and the In gold I4# layer film 14 are etched to expose the compound semiconductor 2, and the electrode hole 10 and the element parting line 1 are etched.
form 1. At this time, as shown in FIG. 3(C), the anodic oxide film 8 and the etching solution do not come into contact with each other in the groove 5, and the single electrode hole 10 and the element dividing line 12 are formed, so the problems like those in the conventional array are avoided. It doesn't happen.

Next, using a metal mask, In is evaporated to cover the electrode hole 10 to form the electrode 6, and finally, the device is divided 41.
The wafer 7 is cut along the lines 12 using a dicing machine to manufacture infrared sensing elements as shown in FIG.

In the above embodiment, the In metal @*l1a14 was also etched when forming the electrode holes 10, but it is also possible to selectively etch only the ZnS film 9 and use the exposed deposited film as an electrode.

Furthermore, in the above embodiment, a single-element infrared sensing element was produced by dividing each element at the end, but it is also possible to produce a 7-ray type element or a matrix type element by dividing it into every few elements.

Furthermore, in the above embodiment, the U-shaped groove 13 is formed,
Although a single-element type infrared sensing element has been made, for example, a 7-ray type element can also be made in which comb-shaped grooves are formed and each gap in (2) is an l element.

[Effects of the Invention] As explained above, the present invention uses an infrared sensing element
- On the top, a groove with a depth equal to or deeper than the high-resistance substrate is formed, surrounding the light-receiving surface and at least one of the electrodes, and a metal evaporation film of a predetermined shape is formed, and the metal evaporation,
The first protective film was formed by anodizing the sea urchin using the F film as a mask, and then the second protective film was formed to cover the first protective film. Since the device can be manufactured without bringing the anodic oxide film into contact with chemicals, it has an excellent effect of improving the yield of the device.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the structure of an original 24-electrode infrared sensing element according to an embodiment of the present invention, and FIG.
3(a) to 3(C) are diagrams showing the manufacturing process of the infrared sensing element according to the present invention, and FIG. 4 is a plan view showing the structure of a conventional photoconductive type infrared sensing element. Figure 5 is a sectional view taken along v-vi in Figure 4, and Figures 6 (a) to (C).
) is a diagram showing the manufacturing process of a conventional infrared sensing element. In the figure, 1 is a high-resistance substrate, 2 is a compound semiconductor, and 3 is a high-resistance substrate.
is the light-receiving surface, 4 is the ml protective film, 5 is the m2 protective film, 6 is the polarization, 7 is the wafer, 12 is the element dividing line, 13 is the fold-back groove, 14 is the metal A7! It is a lf film. Note that the same reference numerals in each figure indicate the same or corresponding parts. Agent: Masuka Oiwa (2 others; Figure 1, Figure 2, Figure 3, Figure 4, Figure 5, Figure 6) Procedural amendment (voluntary) 3. Person making the amendment Relationship to the case Patent applicant address Tokyo 2-2-3 Marunouchi, Chiyoda-ku, Tokyo Name (601) Mitsubishi Electric Co., Ltd. Representative Moriya Shiki 4, Agent address 5-5, Mitsubishi Electric Corporation 2-2-3 Marunouchi, Chiyoda-ku, Tokyo (1) Amend 1R13j on page 6, line 13 of specification 8 to "U-shaped groove 13." Figure 3 (Correct C1 as shown in the attached sheet.)

Claims (1)

[Claims] An infrared sensing element wafer is manufactured by forming a compound semiconductor that becomes an infrared sensing element on a high resistance substrate. forming grooves in a matrix;
forming an oxidizable metal vapor deposited film of a predetermined shape on the infrared sensing element wafer; and anodizing the infrared sensing element wafer using the metal vapor deposited film as a mask to form a first protective film on the light receiving surface. a step of forming a second protective film on the first protective film so as to cover the first protective film; and dividing electrodes and elements on the infrared sensing element wafer so as not to come into contact with the first protective film. 1. A method of manufacturing an infrared sensing element, comprising the step of forming a line.