JPH0449271B2 - - Google Patents

Description

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

[Conventional technology]

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

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

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

First, a compound semiconductor 2 such as HgCdTe is formed to a predetermined thickness on a high-resistance substrate 1 by a method such as epitaxial growth, and an infrared sensing element wafer (hereinafter simply referred to as wafer) 7 is manufactured.

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, a ZnS film 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, 1 of the anodic oxide film 8 and ZnS film 9 is
The part was etched using photolithography, and the image shown in Fig. 6a
An electrode hole 10 is made to expose the compound semiconductor 2.

Next, using a metal mask or the like, a material to be an electrode, for example, an In film 11, is deposited on a portion other than the region where the light receiving surface 3 is to be formed, as shown in FIG. 6b.

After that, the In film 1 is
1. Part of the ZnS film 9, anodic oxide film 8, and compound semiconductor 2 is etched using photolithography until it reaches the high-resistance substrate 1, forming a device dividing line 12 as shown in FIG. 6c. .

Finally, the infrared sensing element as shown in FIG. 4 was manufactured by cutting into individual elements along the dividing line 12 of the element using a dicing saw or the like.

[Problem that the invention seeks to solve]

However, in the conventional method as described above, cracks occur in the first protective film 4 and the second protective film 5 when forming the electrode hole 10 and the parting line 12 of the element, making it difficult to manufacture an infrared sensing element. The problem was that it was difficult. This is HgCdTe anodic oxide film 8
This problem arose because the side etching did not stop within a short range and the etching solution penetrated into the anodic oxide film below the resist because the resist was a film that was very sensitive to chemicals.

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:
On an infrared sensing element wafer manufactured by forming a compound semiconductor layer serving as an infrared sensing element on a high resistance substrate, a high resistance forming a continuous groove with a depth reaching or deeper than the substrate, and on the infrared sensing element wafer,
forming an oxidizable metal vapor deposited film in a shape that covers areas other than the grooves and each area of the light receiving surface, and anodizing the infrared sensing element wafer using the metal vapor deposited film as a mask; a step of forming a second protective film on the first protective film so as to cover the first protective film; and a step of not bringing the first protective film into contact with the infrared sensing element wafer. The method includes a step of forming electrodes and dividing lines for the elements.

[Effect]

In this invention, the anodic oxide film, which is the first protective film, is selectively formed by the action of the grooves and the metal vapor deposited film, so the anodic oxide film is not exposed to chemicals such as etching solution in subsequent steps. It is possible to form electrode holes and element dividing lines without using a wafer.

〔Example〕

FIG. 1 is a plan view showing the structure of a photoconductive infrared sensing element according to an embodiment of the present invention, FIG. 2 is a sectional view thereof, and FIGS. 3 a, b, and c are infrared sensing elements according to the present invention. It is a figure showing the manufacturing process of an element.

In these figures, 1 to 10 and 12 are the same as shown in the above-mentioned figures 4 to 6, and 1
3 is a U-shaped groove, and 14 is a metal vapor deposited film. The U-shaped groove 13 is formed so as to surround the region where the light receiving surface 3 is to be formed and the region where one of the electrodes 6 is to be formed.

Hereinafter, a method for manufacturing an infrared sensing element according to the present invention will be explained using FIG. 3.

First, as in the conventional example, a compound semiconductor 2 such as HgCdTe is formed to a predetermined thickness on a high-resistance substrate 1 by a method such as epitaxial growth, and a wafer 7 is manufactured.

Next, the wafer 7 is etched using photolithography to form a U-shaped groove 13 as shown in FIG. 3a. The U-shaped groove 13 is dug to reach or be deeper than the high-resistance substrate 1.

Next, for example, In is vapor-deposited on the wafer 7,
A metal vapor deposited film 14 having a shape as shown in FIG. 3b is formed.

Next, as in the conventional example, the wafer 7 is subjected to plasma anodic oxidation to form an anodic oxide film 8 that will become the first protective film 4.

At this time, the metal vapor deposition film 14 serves as a mask, so
The anodic oxide film 8 of the compound semiconductor 2 is formed only on the exposed portion of the metal vapor deposited film 14 in FIG. 3b.

Note that at the initial stage of anodic oxidation, the anodic oxidation 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 current flows through the compound semiconductor 2, so the anodic oxide film 8 of the compound semiconductor 2 can be easily removed. can be formed into

Furthermore, even if the metal vapor deposited film 14 is completely oxidized, the anodic oxidation current reaches the electrode of the plasma anodization device through the compound semiconductor 2 of the metal vapor deposited film 14, so there is no problem in forming the anodic oxide film 8.

As described above, after selectively forming the anodic oxide film 8 which will become the first protective film 4 using the metal vapor deposited film 14 as a mask, the ZnS film 9 which will become the second protective film 5 is sputtered onto the surface of the wafer 7. Form on the entire surface.

Next, using photolithography, as shown in Figure 3c,
Etching the ZnS film 9 and the metal vapor deposited In film 14,
The compound semiconductor 2 is exposed, and an electrode hole 10 and a device dividing line 12 are formed. At this time, as can be seen from FIG. 3c, the electrode hole 10 and the element dividing line 12 can be formed without the anodic oxide film 8 coming into contact with the etching solution, so that the problem unlike the conventional example does not occur.

Next, using a metal mask, In is evaporated to cover the electrode hole 10 to form the electrode 6, and finally, the wafer 7 is cut along the device parting line 12 using a dicing saw, as shown in FIG. Manufactures infrared sensing elements such as

In addition, in the above embodiment, when forming the electrode hole 10,
Although the In metal vapor deposited film 14 was also etched, it is also possible to selectively etch only the ZnS film 9 and use the exposed vapor 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 an array-type element or matrix-type element can also be produced by dividing every few elements. Furthermore, in the above embodiment, a U-shaped groove 13 was formed to produce a single-element type infrared sensing element, but for example, a comb-shaped groove may be formed and an array type in which one comb gap constitutes one element. You can also make elements.

〔Effect of the invention〕

As explained above, the present invention includes an infrared sensing element wafer, which surrounds a light-receiving surface area and at least one electrode connected to the light-receiving surface area, and extends to a depth that reaches or is deeper than a high-resistance substrate. While forming continuous grooves, an oxidizable metal vapor deposition film is formed in a shape that covers areas other than the grooves and each area of the light-receiving surface, and the wafer is anodized using the metal vapor deposition film as a mask to remove the light-receiving surface area. A first protective film is formed, and then a second protective film is formed to cover the first protective film.
Since the first protective film is formed, the device can be manufactured without bringing the anodic oxide film, which is the first protective film, into contact with chemicals, which has the excellent effect of improving the yield of the device.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the structure of a photoconductive infrared detecting element according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the - line in FIG. 1, and FIGS. 4 is a plan view showing the structure of a conventional photoconductive infrared sensing element, FIG. 5 is a sectional view taken along the - line in FIG. 4, and FIGS. It is a figure which shows the manufacturing process of the conventional infrared detection element. In the figure, 1 is a high-resistance substrate, 2 is a compound semiconductor, 3 is a light-receiving surface, 4 is a first protective film, and 5 is a second protective film.
, 6 is an electrode, 7 is a wafer, 12 is an element dividing line, 13 is a U-shaped groove, and 14 is a metal vapor deposition film. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. On an infrared sensing element wafer manufactured by forming a compound semiconductor layer serving as an infrared sensing element on a high-resistance substrate, a high forming a continuous groove with a depth reaching or deeper than the substrate of the resistor, and depositing an oxidizable metal on the infrared sensing element wafer in a shape that covers areas other than the groove and each area of the light-receiving surface. forming a film; 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 area; and depositing this on the first protective film. forming a second protective film so as to cover the second protective film;
A method for manufacturing an infrared sensing element, comprising the step of forming electrodes and element dividing lines on the infrared sensing element wafer so as not to contact the first protective film.