JPS6164173A - Manufacture of infrared detecting element - Google Patents

Abstract

PURPOSE:To improve yield on manufacture by enhancing a step coverage at the stepped section of an adhesive layer. CONSTITUTION:An HgCdTe crystal 22 is bonded onto an insulating substrate 21 by using adhesives 23, and the crystal 22 is abraded, and HgCdTe crystals 12 are shaped to regions 25 and 26 in which a photosensitive section and electrode connecting sections are formed. One parts of adhesives 23 are exposed at that time. The whole HgCdTe crystals 12 are etched, end sections 27 are made gentle, and a process through which first and second conductors are shaped is executed. A laminate consisting of Cr or Ti and Au or Al, In or the like is fitted as a conductor material 29, and these elements are laminated through a film formation method having an excellent step coverage, such as bias sputtering, oblique evaporation, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing an infrared detection element using HgCdTe.

(Prior art) HgCdTe is known as an optimal material for high-sensitivity infrared elements, and infrared detection elements using this are basically formed with electrode terminals on HgCdTe crystals with a thickness of about 10 μm, and The device is configured to detect a change in resistance. The main steps of the conventional manufacturing method of such an infrared detection element are as follows. That is, as shown in FIG. 3(a), K HgCd on the insulating substrate 1
Te crystal 2 is glued and polished, followed by HgC
The dTe crystal is etched to a predetermined thickness, usually about 10 μm, and its edges 3 are made smooth. next,
As shown in FIG. 3(b), a conductor 7t is formed in a portion of the HgCdTe crystal 2 other than the region 4 which is to be a photosensitive portion, that is, in portions 5 and 6 where an electrode connection portion and an electrode terminal are to be formed, by a so-called lift-off method. Furthermore, as shown in FIG. ) was manufactured. The reason why the conductor 7 is formed by the lift-off method is to prevent the material of the conductor 7 from coming into direct contact with the HgCdTe crystal, thereby preventing deterioration of the characteristics of the photosensitive portion 8.

In the figure, 14 indicates 4 turns of Regis).

(Problems to be Solved by the Invention) When forming the conductor 7, the conductor must be formed across the stepped portion 12 at the end of the adhesive layer 11, and electrical connection must be maintained. However, since the adhesive layer 11 is generally several micrometers thick, and the step portion 12 is a nearly vertical step with a height of several micrometers, so-called step breakage is likely to occur, making electrical connection impossible. It has to be inadequate. These steps can usually be improved by film formation methods such as bias sputtering and oblique evaporation.
On the contrary, it makes lift-off difficult. In this way, with conventional manufacturing methods, it is extremely difficult to improve the problem of step breakage and to simultaneously improve the lift-off.This not only lowers the manufacturing yield, but also reduces reliability, such as conduction failure during device operation. was inviting.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an infrared detection element that eliminates the above-mentioned drawbacks, has a good manufacturing yield, and is highly reliable.

(Means for Solving the Problems) The present invention includes a step of bonding an HgCdTe crystal onto an insulating substrate and polishing it, shaping the HgCdTe to the dimensions of a region where a photosensitive part and an electrode connection part are to be formed, and a step of exposing a portion of the adhesive layer; a step of etching and removing the HgCdTe crystal to a predetermined thickness and smoothing its edges; A step of forming a conductor and the Hg
forming a second conductor from a region of the CdTe crystal to be an electrode connection part to the first conductor by a lift-off method;
This method of manufacturing an infrared detecting element is characterized by performing a step of etching the conductor and the conductor together into the shapes of a photosensitive part, an electrode connection part, and an electrode terminal.

(Example) Hereinafter, a method for manufacturing an infrared detection element of the present invention will be explained using the drawings.

Figure fX1 is a sectional view and a plan view showing an embodiment of the manufacturing method of the present invention in the order of steps. First, as shown in the cross-sectional view of FIG.
A gCdTe crystal 22 is bonded and polished to a thickness of 30 to 60 μm. As the insulating substrate 21, sapphire or the like having good thermal conductivity is suitable, and as the adhesive 23, low temperature epoxy or the like can be used. Next, as shown in FIG. 1(b), a first resist pattern 24 is used to form areas 25 and 26 where the photosensitive area and the electrode connection area are to be formed.
The HgCdTe crystal 12 is shaped by etching to the dimensions of . At this time, a portion of the adhesive 23 is exposed. Subsequently, as shown in FIG. 1(C), the entire HgCdTe crystal 12 is etched to a predetermined thickness, usually about 10 Am.
(At the same time, the end portion 27 is made smooth. As this etching liquid, a well-known odorous methanol solution as a specular etching liquid is suitable. Next, as a step of forming the first conductor, as shown in FIG. HgCdT as shown in (d)
After covering the entire e-crystal 22 with the second resist pattern 28, a conductive material 29 is laminated. This conductor material 2
As the material 9, a layered layer of Or or Ti and Au, At, In, etc. is suitable.For example, the layer is laminated by a film forming method such as bias sputtering, oblique evaporation, etc., which has good stability. Next, as shown in FIG. 1(, ), etching is performed using the third resist pattern 30 as a mask, and the first conductor 32 is formed on the exposed adhesive layer 23 and the surrounding area 31 where the electrode terminal is to be formed. Let it form.

At this time, the HgCdTe crystal 22 is the second resist) p4
It is protected by turn 28, and in this process HgC
The characteristics of the dTe crystal 22 are not impaired. Then the second
As a step of forming a conductor, as shown in FIG. 1(f), a conductor material 34 is laminated using the fourth resist pattern 33 formed in the area 25 of the HgCdTe crystal 22 as a photosensitive part as a mask. Unnecessary electrode material on the fourth resist pattern 33 is removed by a lift-off method. As a result, a second conductor 35 is formed extending from the region 26 of the HgCdTe crystal 22 to be the electrode connection portion to the first conductor 32. Here, the second conductor material may be the same as the first conductor material, and may be formed to facilitate lift-off. Next, as shown in the cross-sectional view of Fig. 1 (g) and the plan view of Fig. 1 (h),
, the fifth resist in the shape of the photosensitive part, electrode connection part, and electrode terminal) As a mask for t4 turn 36, remove unnecessary parts of H.
By removing the gCdTe crystal and the first and second conductors all at once, a photosensitive part 37, an electrode connection part 38, and an electrode terminal 39 are formed as shown in FIG. Complete the manufacturing of the detection element. The above explanation shows only the main manufacturing steps. In addition to these steps, for example, in the case of oxidation treatment for passivation of HgCdT@ crystal, after the formation of the first conductor, and ZnS This can be done last when forming a dielectric film such as.

In the infrared detecting element manufactured in this way, although the stepped portion 23' of the adhesive layer 23 is an almost vertical step with a height of several μm, as shown in FIG. The step coverage is good, and there are no so-called step breaks. On the other hand, with the conventional manufacturing method shown in Figure 3, it was not possible to make enough step bags and jackets for lift-off, and the result was a step breakage as shown in Figure 2 (b). In addition, although it did not result in step breakage, it became extremely thin, and there were many failures where the device generated heat and broke during operation. In this way, products manufactured using the manufacturing method of the present invention not only have a significantly higher yield rate than products manufactured using conventional manufacturing methods, but also have almost no failures during operation, greatly improving reliability. It was confirmed that

(Effects of the Invention) As explained above, according to the present invention, the step coverage at the stepped portion of the adhesive layer can be improved, the manufacturing yield is good, and an infrared detection element with high reliability can be manufactured. This has the effect of providing a method.

[Brief explanation of the drawing]

Figures 1 (,) to (i) are explanatory diagrams of the main steps of the embodiment of the present invention, and Figures 2 (,) and (b) illustrate the shape of the stepped portion according to the manufacturing method of the present invention and the conventional manufacturing method, respectively. A cross-sectional view showing,
FIGS. 3(a) to 3(d) are main process diagrams illustrating the conventional manufacturing method. In the figure, 21 is an insulating substrate, 22 is an HgCdTe crystal, 27 is an end of the HgCdTe crystal, 25 is a region to be a photosensitive part, 26 is a region to be an electrode connection part, 31 is a region to form an electrode terminal, and 37 is an end part of the HgCdTe crystal. Photosensitive part, 38 is electrode connection part, 3
9 is an electrode terminal, 23 is an adhesive layer, 24.28.30.3
3 and 36 are the 1st. Second. Third. 4th and 5th
In the i4 turn, 29 and 34 are formed conductor materials, 32 is a first conductor, and 35 is a second conductor. Figure 2 (α) (b, 1

Claims (1)

[Claims] (1) A step of adhering an HgCdTe crystal on an insulating substrate and polishing it, and a step of shaping the HgCdTe crystal to the dimensions of the area where the photosensitive part and the electrode connection part will be formed, and exposing a part of the adhesive layer. a step of etching away the HgCdTe crystal to a predetermined thickness and smoothing its edges; a step of forming a first conductor in the exposed adhesive layer and the region where the electrode terminal is to be formed; H
A step of forming a second conductor from a region of the gCdTe crystal that is to be an electrode connection part to the first conductor by a lift-off method, and a step of photo-sensing the HgCdTe crystal and the first and second conductors at once. 1. A method for manufacturing an infrared detecting element, comprising the steps of etching into the shapes of the electrode terminal, the electrode connecting portion, and the electrode terminal.