JPH01283836A - Manufacture of compound semiconductor wafer - Google Patents

Abstract

PURPOSE:To enable a round wafer to be obtained efficiently by removing faulty part such as projection, etc., without damaging the surface so as to process and form it into the round shape for single or many sheets at a time by machine grinding regardless of the shape of a semiconductor substrate. CONSTITUTION:SiO2 films are formed by vapor growth method (CVD method) on both sides of a wafer 1 so that the surface may not be damaged, and fifty sheets of these wafers are piled up with the positions of orientation flats 6 fixed and then adhered with thermosoftening adhesive into cylindrical shape. The periphery of this cylindrical wafer 5 is ground with a cylinder grinding device into the specific cylindrical shape, and further the orientation flat part is ground. After finish of grinding the thermosoftening adhesive is dissolved and removed using trichloroethylene, and further SiO2 film is dissolved and removed by hydrofluoric acid. Hereby, it can improve efficiency, economical efficiency, etc., exceptionally as compared with conventional processing method by manual operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing compound semiconductor wafers, and particularly to a method for processing wafers obtained by liquid phase epitaxial growth.

[Prior art] The liquid phase epitaxial growth method uses, for example, gallium arsenide (
GaAS), gallium aluminum arsenic (GaAj
It is widely used as a growth method for m-v group compound semiconductor wafers such as lAs) and gallium phosphide (GaP), but wafers obtained using this growth method generally have defects such as protrusions on the periphery. easy. Figures 3 and 4 show, for example, a circular GaAS substrate with a (100) plane
This figure shows the situation when the S layer is grown to a thickness of about 50 μm, and a plan view and some partial views are not shown.

In both figures, 1 shows the wafer after epitaxial growth, 2 shows the flat part of the epitaxial layer, 3 shows the protruding part, and 4 shows the substrate.As is clear from these figures, the peripheral part of the wafer 1, especially (010), (010), (001), (00
In the j) direction, protrusions with a height of 100 μm or more may be produced.

These protrusions cause various problems in the subsequent photolithography process. For example, when resist is applied using a spinner, non-uniform areas of the resist concentrate near the protrusions, and the exposure process using a mask aligner is difficult. In some cases, this protrusion comes into contact with the exposure machine and damages the wafer or makes exposure impossible. For this reason, conventionally, after liquid phase epitaxial growth, a shaping operation is performed in which these protrusions are shaved off using a small grinder, file, or the like.

- Generally speaking, circular wafers are much easier to work with than rectangular wafers when automating transportation, small resist work, etc. are taken into account, so wafers are often shaped into circular shapes even if the processing method is cumbersome.

[Problems to be Solved by the Invention] As mentioned above, the protrusions of the wafer that have undergone liquid phase epitaxial growth are scraped off. However, since this is done manually, the finishing accuracy is low, and the process is easily damaged, resulting in problems with the work. It was considered inefficient and uneconomical.

An object of the present invention is to provide a method for manufacturing compound semiconductor wafers that facilitates circular processing of wafers during liquid phase J-bitaxial growth and is advantageous in terms of work efficiency and economy.

[Means for Solving Problem 11] The present invention provides a method for manufacturing a compound semiconductor wafer in which an epitaxial layer is formed on a semiconductor substrate using a liquid phase epitaxial growth method, in which the wafer after the epitaxial layer is formed on the semiconductor substrate. Regardless of the shape, it is characterized by mechanically grinding single or multiple wafers at the same time to remove protrusions and other defects without damaging the surface, and process and shape them into a circle, thereby achieving the objective by efficiently obtaining circular wafers. It was measured.

[Function] In the compound semiconductor wafer manufacturing method of the present invention, when manufacturing a ■-■ group compound semiconductor wafer such as GaAS using a liquid phase epitaxial growth method, for example, a silicon dioxide (Si02) film is formed on both sides of the wafer. When processing multiple wafers at the same time, the wafers are glued together with heat-softening adhesive to form a cylindrical shape, which is then ground to the required diameter to form the cylindrical shape. After that, the orientation flat portion is ground, and then the adhesive and SiO2 film are dissolved and removed to form a circular wafer. Also, when processing a square wafer into a circular wafer, the outer periphery is ground using a chamfering device and processed into a circular shape.
In any of the above cases, the processed wafer does not have protrusions or other defects, and high-quality wafers can be obtained with high efficiency.

[Example] Examples of the present invention will be described below.

Example 1: N-type GaA with a diameter of 54 mm and a thickness of 0.355 W
An epitaxially grown layer was grown to a thickness of 80 μm by doping silicon (S i ) onto the S wafer by a dip-type liquid phase epitaxial growth method.

This wafer has a pn junction formed in the epitaxial layer and is used for an infrared light emitting diode.

FIG. 1 shows a wafer according to this embodiment, where 2 indicates a flat portion and 3 indicates a protruding portion, as in FIG. 3. In addition to the protrusions generated by normal growth, abnormal growth is also formed in the protrusion 3 due to contact between the wafer and the graphite growth container.

5i0211 is formed on both sides of the wafer 1 by vapor phase epitaxy (CVD) to prevent damage to the surface, and 50 of these wafers are stacked with the orientation flat at a constant position and thermally softened. The outer periphery of this cylindrical wafer was ground into a cylindrical shape with a diameter of 50 cm using a cylindrical grinder, and the orientation flat part was further ground into a width of 10 MIR. 1st
In the figure, 5 shows the wafer after processing, and 6 shows the orientation flat part.

After grinding, the heat-softening adhesive is dissolved and removed with trichlorethylene, and the S i O2m is further dissolved and removed with hydrofluoric acid.

Diameter 5 with protrusions and other defects removed in this way
0m+, orientation flat width 10m+ Ga
Fifty As wafers can be obtained at the same time.

In order to create light emitting diodes using this R wafer, a light emitting diode pattern was formed by coating the wafer with photoresist, but the thickness of the photoresist could be made uniform and exposure could be carried out smoothly. , a light emitting diode with good characteristics can be obtained. It was found that the acceptance rate of the products was improved by approximately 20% compared to the case of manual processing, and the processing time per piece was reduced to less than 1/3 compared to the case of manual processing.

Example 2 Length of one side is 45M1 Thickness is 0.3511m
p-type GaA Aj! by liquid phase epitaxial growth method on the p-type GaAS parked in Aj! As (x=1−xx×0.37> layer was formed to a thickness of 20 μm, and n-type Ga1
．． AfJ, As (Y=0.6) layers were continuously grown to a height of 30 μm.

This wafer was used to manufacture red light emitting diodes, but a protrusion was formed on the edge of the wafer.

FIG. 2 shows the wafer in this case, where 7 is a rectangular wafer after epitaxial growth. 2 and 3 indicate a flat portion and a protrusion, respectively, as in FIG.

SiO2 on both sides of this wafer 7! l! J was formed by the CVD method, and then the outer peripheral portion of the wafer 7 was ground using a chamfering device to form a circular wafer having a diameter of 41 mm, and the edges were further chamfered. In FIG. 2, reference numeral 8 indicates the wafer after processing, and reference numeral 9 indicates the orientation flat portion.

In this way, a circular wafer with defective parts such as protrusions removed from the square wafer 7 was obtained, and the characteristics of the light emitting diode obtained from this wafer were also good as in Example 1.

In each of the above embodiments, the shape of the substrate on which epitaxial growth is performed is circular or square.
This does not have to have a specific shape, but may be rectangular or other irregular shapes.

Methods for extracting circular wafers from these substrates include a method of stacking a large number of wafers in a cylindrical shape and grinding them as shown in Example 1, and a method of machining them with a chamfering machine as shown in Example 2. Various other methods can be used, such as a hollowing method using ultrasonic waves and a grinding method using a beveling device. Note that distortion of the wafer that occurs during processing can be removed by etching.

In addition to the 5102 film, a resist film or the like can be used as a protective film for preventing scratches during processing.

[Effects of the Invention] As described above, according to the present invention, the following effects can be obtained.

(1) When growing an epitaxial layer using a liquid phase epitaxial growth method, a circularly shaped wafer can be obtained by removing defects such as protrusions that occur at the edge of the wafer.

(2) Since processing into circular wafers can be performed by mechanical processing, efficiency, economy, etc. can be significantly improved compared to conventional manual processing methods.

(3) Processing and shaping through automation will become a new skill, and it will be possible to mass produce wafers and improve quality and quality, so the performance of various devices manufactured using this technology will be dramatically improved. can.

[Brief explanation of the drawing]

1 and 2 are wafer surface views showing one embodiment of the compound semiconductor wafer manufacturing method of the present invention, FIG. 3 is a wafer surface view after liquid phase epitaxial growth, and FIG. A partial cross-sectional view is shown. 1.7: Wafer after epitaxial growth, 2: Flat
Part 3: Projection part 5.8: Circular wafer after processing.

Claims (1)

[Claims] 1. In a method for manufacturing a compound semiconductor wafer in which an epitaxial layer is formed on a semiconductor substrate using a liquid phase epitaxial growth method, the wafer after the epitaxial layer is formed is mechanically ground regardless of the shape of the semiconductor substrate. A method for manufacturing compound semiconductor wafers, which comprises removing defective parts such as protrusions and shaping a compound semiconductor wafer individually or simultaneously into a circular shape. 2. The method for manufacturing a compound semiconductor wafer according to claim 1, wherein the wafer is processed and shaped after forming a protective film on at least the epitaxial layer surface side during the mechanical grinding. 3. The method for manufacturing a compound semiconductor wafer according to claim 2, wherein the processed and shaped wafer is subjected to etching to remove distortions caused during processing, and then the protective film is removed.