JPH0546708B2 - - Google Patents

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 technology) HgCdTe is known as the most suitable material for high-sensitivity infrared elements, and infrared detection elements using it basically form electrode terminals on HgCdTe crystals with a thickness of about 10 μm, and resist resistance between them. The device is configured to detect changes. The main steps of the conventional manufacturing method of such an infrared detection element are as follows. That is, as shown in FIG. 3a, an HgCdTe crystal 2 is bonded onto an insulating substrate 1 and polished, and then this HgCdTe crystal is etched to a predetermined thickness, usually about 10 μm, and its edges are etched. Make 3 gentle. Next, as shown in FIG. 3b, a conductor 7 is applied to the portions of the HgCdTe crystal 2 other than the area 4 that will be the photosensitive area, that is, the portions 5 and 6 that will form the electrode connection portions and electrode terminals, by a so-called lift-off method. Form. Furthermore, Figure 3c
As shown in FIGS. and d, the HgCdTe crystal 2 and the conductor 7 were collectively etched into the shapes of the photosensitive portion 8, the electrode connection portion 9, and the electrode terminal 10. 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 a resist pattern.

(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, the adhesive layer 11 is generally several μm thick,
Since the stepped portion 12 is an almost vertical step with a height of several micrometers, so-called step breakage is likely to occur, and the electrical connection inevitably becomes insufficient. Such step breakage can usually be improved by film forming methods such as bias sputtering or oblique evaporation, but it makes lift-off difficult. In this way, with conventional manufacturing methods, it has become extremely difficult to simultaneously improve step breakage and lift-off, which not only reduces manufacturing yield but also reduces reliability due to poor conduction during device operation. .

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 high manufacturing yield, and is highly reliable.

(Means for Solving the Problems) The present invention includes a process 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 partially exposing 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 first conductor in the exposed adhesive layer and the region where the electrode terminal is to be formed; A step of forming a second conductor from a region to be an electrode connection part to the first conductor by a lift-off method, and a step of forming the HgCdTe crystal and the first and second conductors into a photosensitive section at once. and a step of etching into the shape of the electrode connection portion and the electrode terminal.

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

FIG. 1 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.
Glue the HgCdTe crystal 22 using
Polish to a thickness of 60μm. As this 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. 1b, using the first resist pattern 24, the dimensions of the areas 25 and 26 where the photosensitive area and the electrode connection area are to be formed are adjusted.
The HgCdTe crystal 12 is shaped by etching.
At this time, a portion of the adhesive 23 is exposed. Subsequently, as shown in FIG. 1c, the entire HgCdTe crystal 12 is etched to a predetermined thickness, usually about 10 μm, and at the same time, the edges 27 are made smooth. As this etching solution, a bromine methanol solution, which is well known as a mirror etching solution, is suitable. next,
In the step of forming the first conductor, as shown in FIG. 1d, after covering the entire HgCdTe crystal 22 with a second resist pattern 28,
Laminate. The conductor material 29 is suitably made of Cr or a stack of Ti and Au, Al, In, etc., and is laminated by a film forming method with good step coverage, such as bias sputtering or oblique evaporation. Next, as shown in FIG. 1e, etching is performed using the third resist pattern 30 as a mask to form the first conductor 32 in the exposed adhesive layer 23 and the electrode terminal formation region 31 around it. At this time, the HgCdTe crystal 22 is protected by the second resist pattern 28, and the characteristics of the HgCdTe crystal 22 are not impaired in this step. Subsequently, as a step of forming a second conductor,
As shown in FIG. 1f, 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 so-called 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. 1g and the plan view of FIG. 1st and 2nd
By etching away the conductors all at once, a photosensitive portion 37, an electrode connection portion 38, and an electrode terminal 39 are formed as shown in FIG. 1I, thereby completing the manufacture of the infrared detection element. Note that the above explanation shows only the main manufacturing steps, and in addition to these steps, for example, in the case of oxidation treatment for passivation of HgCdTe crystal, after the formation of the first conductor, and oxidation treatment of ZnS etc. When forming a dielectric film, it can be performed last.

The infrared film detection element manufactured in this way is shown in Fig. 2a.
As shown in FIG. 2, although the step portion 23' of the adhesive layer 23 is an almost vertical step with a height of several μm, the step coverage of the formed conductor 32 is good, and so-called step breakage does not occur. Not yet. On the other hand, with the conventional manufacturing method shown in Figure 3, it is not possible to provide sufficient step coverage for lift-off, resulting in step breakage as shown in Figure 2b; Although not yet extremely thin, the device became extremely thin, resulting in 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 high, and the method for manufacturing an infrared detection element is highly reliable. It has the effect of providing the following.

[Brief explanation of drawings]

Figures 1 a to i are explanatory diagrams of the main steps of the embodiment of the present invention, Figures 2 a and b are sectional views showing the shape of the stepped portion according to the manufacturing method of the present invention and the conventional manufacturing method, respectively, and Figure 3 a -d are main process diagrams illustrating a conventional manufacturing method. In the figure, 21 is an insulating substrate, 22 is HgCdTe
Crystal, 27 is the end of the HgCdTe crystal, 25 is the area to be the photosensitive part, 26 is the area to be the electrode connection part, 31
37 is a region forming an electrode terminal, 37 is a photosensitive portion, and 38 is a region where an electrode terminal is formed.
39 is an electrode terminal; 23 is an adhesive layer; 24, 28, 30, 33, and 36 are first, second, third, fourth, and fifth resist patterns, respectively; 29 and 34 are finished resist patterns; Filmed conductor material, 32
is the first conductor, and 35 is the second conductor.

Claims (1)

[Claims] 1. A process of bonding an HgCdTe crystal on an insulating substrate and polishing it, shaping the HgCdTe crystal to the dimensions of the area where the photosensitive part and the electrode connection part are to be formed,
A step of partially exposing the adhesive layer and the HgCdTe
a step of etching the 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; and an electrode of the HgCdTe crystal. A step of forming a second conductor from a region to be a connection portion to the first conductor by a lift-off method, and a step of forming the HgCdTe crystal and the first and second conductors at a photosensitive portion 1. A method of manufacturing an infrared detection element, comprising the step of etching into the shape of an electrode connection part and an electrode terminal.