JPH0348465A - Manufacture of infrared detector - Google Patents

Abstract

PURPOSE:To easily form a plurality of compound semiconductor crystal layers having a fixed thickness by removing a compound semiconductor crystal by polishing the crystal to the surface of their supporting substrate after forming a plurality of recessed sections on the surface of the substrate and growing the crystal on the surface of the substrate. CONSTITUTION:A plurality of recessed sections 1a is formed on a sapphire substrate 1, with the depth of the recessed sections 1a being fixed at, for example, 10mum. Then, after an Hg1-xCdxTe crystal 2' is grown on the surface of the sapphire substrate 1 on which the recessed sections 1a are formed, the Hg1-xCdxTe crystal 2' is polished to the upper surface 1b of the sapphire substrate 1 so as to remove the crystal 2'. Thus a plurality of Hg1-xCdxTe crystal layers are formed on the substrate 1.

Description

[Detailed Description of the Invention] Summary Regarding a method for manufacturing an infrared detector using a compound semiconductor crystal, the present invention aims to provide a method for easily forming a plurality of compound semiconductor crystal layers having a constant layer thickness on a supporting substrate, In a method for manufacturing an infrared detector in which a plurality of light receiving parts are arranged on a support substrate, a plurality of recesses are formed on the surface of the support substrate, and a compound semiconductor crystal is formed on the surface of the support substrate in which the recesses are formed. After elongating, the compound semiconductor crystal is polished to the surface of the support substrate to remove the compound semiconductor crystal in a portion other than the recess.

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing an infrared detector using a compound semiconductor crystal.

Infrared sensors can detect the presence, shape, temperature, strength, etc. of a target object without coming into contact with it, so it can be used for weather observation using artificial satellites, crime prevention, disaster prevention, geological and resource surveys, and medical applications using infrared thermography. It is used in many fields such as Such infrared sensors include pyroelectric elements,
There are thermal type sensors using thermomobiles, etc., and photoelectric effect type (quantum type) sensors using semiconductors.Generally, thermal type sensors have no wavelength dependence of sensitivity, but because the sensitivity is low and the response speed is slow, real-time infrared sensors are used. On the other hand, photoelectric effect sensors have high sensitivity and fast response speed, but require cooling of the device to liquid nitrogen temperature.

Photoelectric effect type infrared sensors include photoconductive type, photovoltaic type, M
It is classified as IS type. Among these, photoconductive sensors utilize resistance changes upon irradiation with light, and include those that use intrinsic semiconductors such as cadmium mercury telluride (H g l-X C d It T e ) and PbSSPbSe;
i:. In, Sl: Ga, Ge: HgSGe: Au
Some use extrinsic semiconductors doped with impurities, such as .

Recently, Hgr-xc as mentioned above
Photoconductive infrared sensors using compound semiconductor crystals such as dxTe are being mass-produced, but the manufacturing process is difficult and the yield is low, so there is a need for an easier manufacturing process.

Prior Art Referring to FIG. 4, the structure of a conventional infrared detector is shown. 11 is a sapphire substrate, and on this sapphire substrate 11 an H gr-XC d XTe crystal 12 is adhered with an adhesive 13 .

14 is an infrared light receiving section, and the width of the light receiving section 14 is regulated by forming electrodes 15 and 15 on both sides.

The electrode 15 is made of metal such as In or Au, and is formed by a lift-off method or the like.
x C d x T e It is ohmically connected to the crystal 12 . A bonding wire 16.16 for signal extraction is bonded to this electrode 15.15 by ultrasonic bonding or the like. Although not shown, the surface of the Hg+-CdXTe crystal 12 is protected by forming a passivation film.

The infrared detecting element having such a structure is made of sapphire substrate 11.
When infrared rays are incident on each of the light receiving sections 14, the resistance value between the electrodes 15 and 15 changes depending on the intensity of the infrared rays, and this change is detected as a voltage change.

H g l-X C d ) I Te The thickness of the crystal is
To improve the sensitivity of infrared detectors, thin (for example, 10μ
m) It is necessary to shape the material, and for this reason conventionally the following method has been used to obtain a predetermined thickness. That is, H g l− is grown at a predetermined composition ratio by vapor phase or liquid phase epitaxial method on a crystal growth substrate made of CdTe or the like.
II C dx T. After bonding a plurality of e-crystals with the surface opposite to the crystal preceptor substrate onto the sapphire substrate 11 with an adhesive 13, the crystal precipitator substrate and Hg +-x C
A portion of the d 11 Te crystal was removed by polishing to form a Hg+-XCdXTe crystal 12 with a predetermined thickness (for example, 10 μm).

Problems to be Solved by the Invention As described above, in the past, compound semiconductor crystals were grown to a certain extent on a substrate for crystal lengthening, a plurality of these were bonded to a sapphire substrate, and then polished to form a crystal layer of a predetermined thickness. It is said that However, this crystal layer needs to be formed very thin, for example 10 μm, in order to improve the sensitivity of the infrared detector.
It is difficult to uniformly polish each crystal layer to a constant thickness, which causes a problem in that detection sensitivity varies from device to device.

The present invention has been made in view of these points, and an object of the present invention is to provide a method for easily forming a plurality of compound semiconductor crystal layers having a constant layer thickness on a support substrate.

Means for Solving the Problems The technical problem described above is to form a plurality of recesses with a depth of, for example, 10 μm on the surface of a support substrate made of sapphire or the like, and to form Hgl-XCdwTe or the like on the surface of the support substrate in which the recesses have been formed. This problem can be solved by elongating the compound semiconductor crystal to a certain length, and then polishing the compound semiconductor crystal to the supporting substrate surface to remove the compound semiconductor crystal that has elongated to a certain extent outside the recess.

Function According to the method of the present invention, after a compound semiconductor crystal is grown on a support substrate in which a plurality of recesses are formed, the compound semiconductor crystal is polished.

When a part of the compound semiconductor crystal is removed by polishing and reaches the support substrate surface, the support substrate is hard and cannot be polished any further. As a result, the compound semiconductor crystal remains only in the recess formed in the supporting substrate, and if the recess is set to have a depth of, for example, 10 μm, then a plurality of 10 μm
A compound semiconductor crystal having a thickness of m is easily formed.

Since the compound semiconductor crystal layer is formed on the support substrate using this method, there is no difference in the layer thickness of the compound semiconductor crystal of each element as in conventional construction, and the layer thickness of all the compound semiconductor crystals can be ensured. can be made to a predetermined thickness to improve the characteristics of the infrared detector.

Example Embodiments of the present invention will be described in detail below based on the drawings.

FIGS. 1(A), (B), and (C) are embodiments of the present invention, in which a compound semiconductor (Hgl-MCdwTe) crystal is placed on a supporting substrate (sapphire substrate). It is a figure for explaining the method of shaping. 2 and 3 are a plan view and a sectional side view of an infrared detector constructed using the method of the present invention.

1 is a sapphire substrate, and on this sapphire substrate 1, a H g l-X C d , lTe crystal 2 is formed. This H gr-w C d X T e
The method for forming the crystal 2 will be explained with reference to FIG. 1. First, as shown in FIG. 1(A), a plurality of recesses 1a are formed on the sapphire substrate 1. The depth of this recess 6 portion 1a is, for example, IO μm. Next, as shown in (B), H-g+-CdXTe crystal 2' is grown at a predetermined composition ratio on the surface of the sapphire substrate 1 in which the recess 1a is formed by vapor phase or liquid phase epitaxial method. urge

Then, as shown in (C), this H g +-* C d )l grown on the sapphire substrate 1
By polishing and removing the T e crystal 2' up to the upper surface 1b of the sapphire substrate l, a plurality of H g l with a constant thickness is formed.
-X C d X T e crystal 2 is formed.

Referring to FIGS. 2 and 3, 4 is an infrared receiver, 5 is
, 5 are a pair of electrodes, and by forming the electrodes 5.5 from both sides of each crystal 2, the width of the light receiving portion 4 is regulated. The surface of the Hg+-Cd,ITe crystal 2 is protected by a passivation film 3. The electrode 5 is made of a metal such as InSAu, and H g +-* is formed by a lift-off method or the like.
It is ohmically connected to the C d II Te crystal 2. Although not shown, bonding wires for signal extraction are bonded to these electrodes 5 by ultrasonic bonding or the like. When infrared rays are incident on the light receiving section 4, the resistance value between the electrodes 5.5 changes depending on the intensity of the infrared rays, and this change is detected as a voltage change.

According to this embodiment, after growing the Hg1-,I CdXTe crystal 2' on the sapphire substrate 1 having a plurality of recesses 1a, the Hg1-XCdH7e
A part of the crystal 2' is removed by polishing. Once polishing has been performed up to the upper surface 1b of the sapphire substrate 1, since the sapphire substrate 1 is hard, it cannot be polished any further.
d
) I T e crystal 2 will remain. Since the depth of the recess 1a is, for example, 10 μm, a plurality of Hg l'-X C d H 7 e crystals 2 having a thickness of IO μm are formed.

In this way, Hg+-Cd,
Since the Te crystal 2 is shaped, the layer thickness of each compound semiconductor crystal does not become uneven as in the conventional structure, and the layer thickness of all the Hg+-XCd and Te crystals 2 is ensured to a predetermined thickness. be able to.

Effects of the Invention According to the method of the present invention, a compound semiconductor crystal is grown to a certain extent on a support substrate having a plurality of recesses, and then the compound semiconductor crystal outside the recesses is removed by polishing. , it becomes easy to process the compound semiconductor crystal layer to a predetermined thickness, and the layer thickness of each compound semiconductor crystal can be made constant, which allows for infrared detection with less variation in characteristics. This has the effect of making it possible to provide containers.

[Brief explanation of drawings]

Figure 1 (A). (B) and (C) are diagrams of an embodiment of the present invention, in which a sapphire substrate is coated with Hg. −． FIG. 2 is a plan view of an infrared detector showing an embodiment of the present invention, FIG. 3 is a side sectional view of the same, and FIG. 4 is an explanatory diagram of the prior art. . 1... Sapphire substrate, 1a... Concavity, 2.2'-Hg+ w Cd. Te crystal, 4... Light receiving part, 5... Electrode.

Claims (1)

[Claims] A method for manufacturing an infrared detector in which a plurality of light receiving sections (4) are arranged on a support substrate (1), comprising: forming a plurality of recesses (1a) on the surface of the support substrate (1); After growing a compound semiconductor crystal (2') on the surface of the support substrate (1) on which the recess (1a) is formed, the compound semiconductor crystal (2') is polished to the support substrate surface (1b), A method for manufacturing an infrared detector, characterized in that a portion of the compound semiconductor crystal (2') other than the inside of the recess is removed.