JPH0354184A - Crucible for crystal production - Google Patents

Abstract

PURPOSE:To increase yield of wafer by making horizontal cross sectional shape of a part or whole inner wall of crucible to have one or several linear parts with a circle as a basic shape, or to have polygonal shape. CONSTITUTION:A crucible for crystal production is constructed with a well part 4 keeping seed crystal 7 and having approximately rectangular cylindrical shape, diameter-increasing part 5 having approximately hollow right pyramidal shape arriving to linear body part 6 and linear body part 6 having rectangular cylindrical shape. Seed crystal 7 of GaAs of <100> direction, GaAs raw material and B2O3 as liquid sealant 9 are charged in said crucible for crystal production and melted by heat, then cooled to afford grown single crystal 8.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a crystal manufacturing crucible that defines a crystal shape used in a method of crystal growth by cooling and solidifying a melt in a crucible, such as the vertical Bridgman method or the vertical temperature gradient solidification method. It's about ho. [Prior art] The crystal manufacturing method used in a wide range of crystal manufacturing methods such as the vertical Bridgman method and the vertical temperature gradient solidification method using conventional bolt crystals has a horizontal cross-sectional shape as shown in Fig. 4. It has a circular shape, and as shown in the vertical cross-sectional view of FIG. 4(b), it has a structure in which an elongated well 1 for accommodating seed crystals is provided at the bottom of the crucible. The shape of crystals produced using crystal production methods such as the vertical Bridgman method and vertical temperature gradient solidification method is the same as that of Ruriha, so the horizontal cross-sectional shape of crystals produced using conventional crystal production crucibles is similar to that of crystal production crucibles. It has the same circular shape as the horizontal cross-sectional shape. -2! This kind of circular crystal is used for manufacturing various semiconductor parts! When used as a temporary crystal, the orientation
It is necessary to process and form marks on the crystal that indicate the crystal orientation, called flats. In addition, when a circular crystal is used as a substrate crystal for manufacturing a light-receiving element for a solar cell, the wafer must be processed into a square shape in order to increase the packing density of light-receiving elements per unit area. FIGS. 5 and 6 show the shape of the orientation flat of a typical wafer for manufacturing semiconductor components. FIG. 5 shows the case of a silicon wafer whose crystal plane orientation is the (100) plane, and there is only one orientation flat 2, and the orientation flat plane is the (0 1 1) plane. Figure 6 shows the orientation flat of a (100) gallium arsenide wafer. There are two orientation flats 23, and the orientation flats are the (011) and (011) planes.
011) surface. Crystallographically, silicon crystals and gallium arsenide crystals belong to the same cubic crystal system and have the property of easily folding into the <110> structure. When cutting out a wafer piece of about 5 mm square, chip cutting is performed using this arm-opening property. Therefore, the orientation flat has a very important meaning for the wafer. Orientation ◆The flat shaping method is to first cut a wafer from a manufactured crystal in a rough direction, determine the crystal plane orientation using an X-ray method, and measure the deviation width from the desired crystal orientation. Next, the material is cut again to correct the deviation width, and a crystal block with the desired crystal plane orientation is manufactured. Next, this crystal block is held in an end face grinder to form one or more orientation flat portions at predetermined positions. By cutting this crystal block into thin pieces, the wafers shown in FIGS. 5 and 6 are obtained. FIG. 7 shows the shape of the wafer (100) surface for gallium arsenide solar cells. In this case, the wafer is square in order to increase the filling rate of the solar cell wafer per unit area of the solar cell panel. This rectangular wafer is obtained by thinly cutting a rectangular prism block processed from a cylindrical crystal using the same orientation flat forming method shown in FIGS. 5 and 6. Conventionally, crystal manufacturing machines with a rectangular horizontal cross-sectional shape have not been used to manufacture single crystals because they can only produce polycrystals, but it is difficult to produce single crystals. [Problems to be Solved by the Invention] As described above, since the conventional crystal manufacturing Ruho used had a circular horizontal cross section, the manufactured crystal with a circular cross section can be used as a wafer for IC manufacturing or for solar cell manufacturing. In order to use the wafer as a commercial wafer, it is necessary to process the wafer into a shape suitable for the intended use, and this not only requires special processing equipment and processing time, but also causes maximum crystal processing loss. It accounts for about 40% of the crystal weight, and from the viewpoint of saving resources, saving energy, and lowering the cost of wafers, there was a strong desire for measures to simplify the wafer forming process, such as orientation ◆flat. The purpose of the present invention is to provide a crucible for crystal growth that can significantly reduce crystal processing losses and processing time during wafer forming processing due to the problem of only obtaining crystals with a circular cross section, which was a problem with conventional crystal growth crucibles. Our goal is to provide the following. [Means and effects for solving the problems] In order to achieve the above object, the present invention provides a crystal growth method for obtaining a single crystal with the same orientation as a seed crystal by storing, melting and cooling a crystal raw material and a rice seed crystal. A crucible for producing crystals that specifies the crystal shape used in a crucible, in which the horizontal cross-sectional shape of a part or all of the inner wall of the crucible is basically circular and has one or more straight parts,
The horizontal cross-sectional shape of part or all of the inner wall of the crucible is polygonal, making it suitable for ICs and solar cells by simply cutting the crystal produced in the crucible into a wafer and folding it once. This allows wafers with the same shape to be obtained. [Example] The present invention repeats crystal manufacturing experiments using the vertical Bridgman method and the vertical temperature gradient solidification method using crucibles with various shapes of horizontal cross-sectional shapes of the inner wall of the crystal manufacturing Ruho which defines the crystal shape. The results showed that stable single crystal growth is possible even if the horizontal cross-sectional shape of the inner wall of the crucible is not circular, and that wafers with shapes suitable for ICs and solar cells can be obtained by simply cutting the crystal into wafers. This was done based on experimental results. The experimental method and experimental results will be described below. FIG. 1(a) is a horizontal cross-sectional shape of the straight body of a crucible showing the experimental method, and FIG. 1(b) is a vertical cross-sectional shape of the same crucible. The shape of the crucible for crystal production was designed assuming that square wafers would be obtained. Reference numeral 4 denotes a well portion in the shape of a square tube that holds the volatilization crystals, numeral 5 denotes a hollow quadrangular pyramid-shaped increasing diameter portion extending from the well portion to the straight body portion, and numeral 6 denotes a rectangular straight body portion with a side length of 5 cm. It is. The crucible was made of pyrolytic boron nitride and had a wall thickness of about 1 m. In this crystal manufacturing crucible, <100> oriented GaAs
Seed crystal 7, 100 grams of GaAs raw material, and 70 grams of boron oxide as liquid sealing material 9 were filled, heated, melted, and cooled to produce crystals. 8 is a growing crystal. As a result of such crystal production experiments, stable single crystal production was achieved. That is, as shown in FIGS. 1(a) and 1(b), the liquid sealant 9 covers the inner wall of the crucible for producing crystals, and the growing crystal 8 is covered with the crystal sealant 9, thereby stably forming a single crystal. Manufacture has been completed. In this case, the crystal part corresponding to the flat part of the inner wall of the crucible is flat as the shape of the crucible, but the corner part of the crystal 1
It was found that 0 tends to become rounded due to surface tension, so it does not align with the corner 11 of the brim, but has a minute curvature with a radius of about 1. From these experimental results, we found that there is no need for a cylindrical crucible for producing single crystals, and that single crystals can be stably produced using square crucibles, and that square wafers cut from crystals produced in square crucibles It has the same crystal quality as that produced with a conventional cylindrical melt hoist, and the wafer yield obtained from one crystal is 1.6% higher than when produced with a cylindrical melt hoist using the same weight of raw material. It was found that the small curvature of the crystal corners does not pose a problem when the crystal is made into wafers and used for device fabrication, but rather has the advantage of being easier to handle and less likely to chip. The present invention was made based on the above-mentioned Kinuta crystal manufacturing experiment. As described above, the present invention produces crystals using a crystal growth crucible that matches the desired shape of the wafer.
The most important feature is that it can produce crystals with the least shape loss due to wafer shape processing.

[Embodiment 1] FIG. 2 is a diagram illustrating the first embodiment of the present invention.
This figure shows a crucible for crystal manufacturing used when manufacturing a (100)-plane gallium arsenide crystal of a C manufacturing wafer by the vertical Bridgman method. 12 is a cylindrical well portion that accommodates the seed crystal, 13 is a hollow conical increasing diameter portion extending from the well portion to the straight body portion, and 14 is approximately cylindrical with an inner diameter of 50 mm and has a specified horizontal cross-sectional shape. There is a straight body member that has two parts, a straight part al5 and a straight part bl6, which indicate the direction of. This straight part al
5 is formed in the [011] direction, corresponding to the (100)-plane seed crystal, and the straight portion b is formed in the [011] direction, corresponding to the (100)-plane seed crystal. In this melting pot (
100) seed crystals, 550 grams of gallium arsenic raw materials, and 60 grams of boron oxide as a corrugated body sealing material,
Crystals were produced by heating and melting all of the gallium/arsenic raw materials and part of the gallium/arsenic seed crystals, and then cooling them. When the crystal produced using the crucible shown in Fig. 2 is cut horizontally from the straight body part, it becomes (100) as shown in Fig. 6.
A flat wafer shape can be obtained. Just by cutting the crystal, the orientation flat 23 of the (011) plane and the (011) plane are neatly shaped straight B 5 0 1
+1 (D wafer was obtained, and there was no need for orientation, flat shape or processing.Compared to the case of obtaining a wafer from a crystal produced using conventional Ruriha, the processing time for orientation, fly} formation was reduced. can be omitted, and the yield of wafers obtained from one crystal is increased by 10%.

[Embodiment 2] Fig. 3 is a diagram for explaining the second embodiment of the present invention, in which a (100)i gallium arsenide antagonist crystal is used as a base plate for a photodetector for a solar field. This shows the Ruho used when manufacturing by the method. 17 is a substantially square cylindrical well portion that accommodates seeds; 18 is a hollow quadrangular pyramid-shaped increasing diameter portion extending from the well portion to the straight body portion; 19
is a rectangular cylindrical body with a side of 5 cm. This rutsuho contains (100) gallium/arsenic seed crystals, 1,000 grams of gallium/arsenic raw materials, and 60 grams of boron oxide, which is a liquid sealing material, and contains all the gallium/arsenic raw materials and one part of the gallium/arsenic seed crystals. Crystals were produced by heating, melting, and cooling. When the gallium arsenide crystal manufactured using the rutsuho shown in Fig. 3 is cut horizontally from the straight body part, each side is approximately 5 am (10 m) as shown in Fig. 7.
0) A flat wafer can be obtained. Compared to the case of obtaining square wafers from crystals produced using conventional crucibles with circular cross-sections, the crystal processing time can be significantly reduced and the wafer yield obtained from one crystal is approximately 1.6 doubled. In addition, although the above example shows the case where the crystal is manufactured by the vertical Bridgman method, the case where the crystal is manufactured by the vertical degree gradient solidification method, and other crystals such as indium phosphorous crystals and cadmium tellurium crystals are manufactured by the vertical Bridgman method or the vertical Bridgman method The effects obtained when manufacturing by the temperature gradient solidification method are the same as those in the above embodiments, and no explanation is required. Further, the shape of the well portion for holding the insert crystal and the diameter-increasing portion may be any shape other than those of the above-mentioned embodiments as long as it realizes stable single crystal production. [Effects of the Invention] As explained above, when a wafer is obtained from a crystal produced using the crystal production crucible of the present invention, the crystal shape processing process for obtaining a desired wafer shape can be simplified; There is an advantage that the wafer yield can be greatly increased and the wafer production cost can be significantly reduced.

[Brief explanation of drawings]

FIG. 1 is a horizontal and vertical sectional view showing the state of crystal production according to the present invention, FIG. 2 is a perspective view of a crucible for producing crystals showing the first embodiment of the present invention, and FIG. FIG. 4 is a vertical and horizontal cross-sectional view of a conventional crystal growth crucible with a well for storing seed crystals, and FIG. FIG. 3 is a perspective view of FIG. DESCRIPTION OF SYMBOLS 1... Well part for accommodating the interpolation crystal, 2... (011) plane part of orientation flat, 3... (0 1 1) plane part of orientation flat,
4. Cheek square cylindrical well part, 5... 1 diameter part, 6.
... Straight body part, 7... Seed crystal, 8... Growth crystal, 9
... Bifurcated body sealing material, 10... Corner part of crystal, 11...
・Corner part of crucible, 12...Cylindrical well part, 13・
...Hollow conical increasing diameter part, 14...Cylindrical straight body part,
15... Straight line part a of the crucible, 16... Straight line part b of the crucible 117... Almost square cylindrical well part, 18... Hollow square pyramid-shaped increasing diameter part, 1... Square cylinder The straight body part of the shape.

Claims (2)

[Claims] (1) In a crystal manufacturing crucible that defines the crystal shape used in a crystal growth method in which a crystal raw material and a seed crystal are stored, melted, and cooled to obtain a single crystal with the same orientation as the seed crystal, a part or all of the crucible is used. A crucible for producing crystals, characterized in that the horizontal cross-sectional shape of the inner wall of the crucible is basically circular and has one or more straight sections. (2) In a crystal manufacturing crucible that defines the crystal shape used in a crystal growth method that obtains a single crystal with the same orientation as the seed crystal by accommodating, melting and cooling the crystal raw material and the seed crystal, part or all of the crucible A crucible for producing crystals, characterized in that the horizontal cross-sectional shape of the inner wall thereof is polygonal.