JPH04132677A - Production of thin plate-shaped single crystal by melt-pressure method - Google Patents

Abstract

PURPOSE:To enable direct production of the subject wafer state thin plate crystal from a molten liquid by using an apparatus capable of ready take-out of the thin plate crystal, charging the molten liquid into a plate shaped vessel having a gap part of a prescribed thickness under pressure and cooling the molten liquid. CONSTITUTION:A vessel 1 having a structure composed by using a ceramics-based electric insulating material such as quartz or Al2O3 and an electroconductive material such as graphite, stainless steel or copper separately or in combination of two kinds of the materials considering wettability with a molten raw material is used. The vessel 1 has a structure composed of separating plates 2, spacer units 3 and a gap 4 capable of determining the thickness of a thin plate. The lower end part of the vessel is opened and the upper end part thereof is connected through a necked part 5 supporting a seed crystal 7 to a suction pipe 6. The inner surface of the vessel 1 is cleaned by acid pickling, etc., then baked so as to remove wettability with the material for the purpose of ready take-out of a thin plate-shaped crystal. A molten raw material is charged into the vessel 1 having the gap 4 adjusted to a desired thickness under pressure utilizing the difference between the pressure of the inside of the vessel and that of the outside of the vessel followed by cooling from the one end of the vessel 1, thus producing the objective single crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION a. Field of Industrial Application According to the present invention, the I! Films, thin film crystals of high-temperature oxide superconductors, thin crystals (wafers) for semiconductor devices (chips), and solar cell substrates have been produced and are used as substrate materials in fields such as the optical and electronic industries. Ru.

b. Prior Art Thin single crystals of semiconductors, magnetic materials, and oxides are essential basic materials in the production of electronic devices and optical devices. In the case of materials that are highly ductile and malleable, such as metals, or in the case of certain insulators, such as quartz glass, which can be processed near their softening temperature, it is difficult to produce these thin plate-like materials. It's simple.

However, in the case of semiconductors and insulators, the film thickness is approximately 0.
．． It has been impossible to produce thin Ia crystals of 1 μm to 500 μm directly from the melt. Therefore, semiconductor elements used in almost all electronic devices are made of large crystals (bulk crystals, e.g.
By slicing ingots (20cm long) and wafers with a thickness of about 500μm (0.5mm) as a substrate crystal, various processes can be carried out. It has been made. This ingot crystal is usually produced by a pulling method or a method called the Bridgman method. Naturally, when processing into a wafer, more than half of the crystal is wasted as shavings, and only about 30% of the original crystal is actually used as a substrate. Moreover, even when used as a device, the thickness of the substrate that is effectively utilized is several μm. If a semiconductor crystal with a thickness of several 100 μm could be directly produced from a melt, the above-mentioned problems would not occur and raw materials could be used most effectively.

EFG (ed.
ge-definad fil+o-fed grow
th) There is a law. As a result, a ribbon-like product has been obtained, but the thickness is approximately 200 μm (0.2 mm), and it is difficult to reduce the thickness to less than 200 μm (0.2 mm). Application of the back fabrication method is still limited to some materials such as St, and it is only slightly used as a substrate for solar cells.

In this method, the die (template) used to determine the shape of the thin plate crystals must be wetted with the melt, and the liquid must climb up the die due to surface tension, so there are limits to the materials that can be used.

Furthermore, it is possible to directly produce semiconductor thin film crystals by a vapor phase method without using bulk crystals, but this poses various problems. This manufacturing method includes vacuum evaporation method (including molecular beam epitaxy method), CVD (Chemica
There is a Vapor Deposition method, but the film thickness is less than 0.01 μm, and it cannot be used as a substrate.
In addition, in the case of compound semiconductors, it is difficult to control the chemical composition ratio in the case of compound semiconductors. No crystals were obtained.

C1 Problems to be Solved by the Invention As is well known in the art, wafer manufacturing technology starts from a single crystal ingot.

The following problems have been pointed out with this technology: (1) Advanced technology is required to make the ingot, the equipment is expensive, and the power consumption for operation is large.

(2) Highly skilled work and time are required to turn an ingot into a wafer.

The time loss is also large.

(3) In order to cut the ingot and polish it, processing loss of material is unavoidable, and also loss of material required to maintain uniform characteristics depending on the position of the ingot is also unavoidable.

These problems determine the cost of semiconductor wafers, but especially in the case of compound semiconductors, which are expensive raw materials, material loss increases manufacturing costs, and waste of rare *a It has also become However, improvements have been made in all of these items to the extent that they are said to be close to their limits, and further cost reductions cannot be expected.

Therefore, the present invention attempts to solve these problems by directly producing wafer-shaped thin plate crystals from rice liquor.

Means for Solving the d0 Problem The following three technical measures were taken to solve the above problems: (1) The growth container for thin plate crystals has a gap approximately equal to the thickness of the wafer, and its upper and lower ends shall have an open structure to facilitate the intrusion of melt by vacuum suction or press-in method using gas pressure.

(2) In order to prevent wettability between the container material and the thin plate crystals and to facilitate removal from the container after crystallization, the surface of the container material should be cleaned by chemical cleaning or vacuum baking.

(3) The growth container is lowered into the melt from the bottom, and after the entire container is in the melt, the melt can be pressurized or vacuumed from the top of the growth container, so that the melt completely fills the inside of the growth container. Crystallization is carried out by gradually lifting the container out of the melt after filling it with liquid.

In the present invention, by taking such technical measures, the thickness can be reduced to 10/
This made it possible to obtain thin plate-like 11j crystals of several mm from 1.

00 action germanium (Ge) and gallium antimony (GaSb
), the container and the plate-like crystals had no wettability, so there was no interaction with each other, and the crystal could be easily removed from the container. In addition, the crystal plane is a mirror surface because it is protected from the outside world by the container. This means that impurity contamination is prevented, and in the case of compound materials, there is an effect of preventing deviations in composition ratio. In terms of quality, this means that uniformity in in-plane characteristics can be improved, and
The favorable result is that there is little thermal strain.

f. Examples The invention will now be described in detail with reference to the accompanying figures. Figure 1 shows a growth vessel for thin plate-like 1i crystals, (a)
(b) is a container structure made of quartz or borosilicate glass, etc.; A container structure made by machining of boron nitride or the like is illustrated. (a)
, (t)), the container has a structure in which the thickness of the thin plate is determined by the partition plate 2, the spacer part 3, and the gap 4. The lower end of the container 1 is open, but the upper end is connected to a suction vibro through a constriction 5.

The constriction 5 holds a seed crystal 7 for obtaining a single crystal. At this time, if the diameter of the upper end of the seed crystal 7 is approximately 1 to 2 mm larger than the inner diameter of the constricted portion 5, its positioning will be facilitated. Note that after cleaning the inner surface of the growth container by pickling, etc.) If vacuum baking is performed at 000°C for 1 hour or more, the wettability between the material and the container will be lost, making it difficult to take out the thin plate crystals from the growth container. is possible.

FIG. 2 shows an apparatus for producing germanium and gallium antimony thin plate-like single crystals using these growth vessels. Here, an example regarding germanium will be shown.

First, the germanium raw material 2 is placed in the quartz crucible 5 and heating is started by the heater 3, and at the same time, the inside of the metal container is evacuated by opening the valve 2+ (b) by the vacuum pump 22 (11). In addition, a seed crystal 23 is inserted into the constriction of the growth container 11 in advance, and the inside of the metal container 1 is evacuated at 860° C., which is below the melting point of germanium. b)2
1 is closed, valve (a) is opened, and gas cylinder 23 is opened.
An inert gas such as helium or argon is introduced through the exhaust pipe (c) 19 at a pressure of about 0 O Torr. Here, the germanium raw material is heated by the heater 3 and has a melting point of 9.
It is maintained at 9900C which is about 30C higher than 59C. The growth container 11 has a vacuum cock (a) 1 at the top of the suction pipe 12.
The 0th order, which is closed at 4 and is filled with inert gas at approximately ]00 Torr as well as its internal metal container,
The growth container 1 is gradually fixed by the vertical drive unit 3 to a position below the germanium molten M surface in the crucible 5. Here, since the pressure inside the growth container 1 is almost equal, the germanium melt does not penetrate into the inside of the growth container.

Then, the vacuum cock (a) 14 is gradually opened and the gas inside the suction vibrator 12 and the inside of the growth container 11 is exhausted with the vacuum pump (a) 18. By doing this, the growth container 24 in the crucible is Due to the pressure difference inside the metal container 1, the germanium melt will fill the growth container 24. At this time, the raw material melt with low viscosity easily enters the growth chamber 4811 with a small pressure difference, but with high viscosity, the gas pump 22 increases the pressure inside the metal container 1, pressurizes the melt, and presses it in. By doing so, the inside of the growth container 24 can be filled. When the melt in the growth container 24 reaches a position where it touches the seed crystal 23, close the vacuum cock (a, ) 14 and wait for a part of the seed crystal 23 to melt 6. When a part of the seed crystal melts, turn the upper and lower Q ! Part J1] 3, by moving the growth container 24 upward at a rate of several mm per hour, the melt 25 in the growth container solidifies from the part away from the surface of the germanium melt, that is, it solidifies into a single cylinder. , crystallization begins. The growth of the crystal 26 in the growth container continues until the growth volume 9511 runs out of the melt, and the growth container is filled with the thin plate-like single crystal. The obtained germanium plate-shaped single crystal could be easily taken out by cutting off the upper end of the growth container because it did not have wettability with the growth container 24 made of quartz glass.

As another example, gallium antimony was tried.

Most of the manufacturing methods are the same as for germanium, but in this case, the crystals obtained were polycrystalline because they were manufactured without using seed crystals. Although we have mainly described examples of germanium here, the thin plate-shaped single crystal manufacturing method using the melt pressurization method of the present invention can be used for a wide range of materials such as metals, oxides, and organic substances by combining various growth container materials. applicable.

g1 Effects of the invention In conventional wafer manufacturing, large single crystal ingots were made, cut, and polished, but the present invention uses a zero-strand method that enables the production of thin plate-like single crystals with a shape close to that of the product. Single crystals do not require the cutting of ingots, as is the case with wafer processing for electronic materials, resulting in a significant reduction in raw material loss. Therefore, the method according to the present invention not only leads to the effective use of scarce resources, but also has the secondary effect of bringing about an overall reduction in manufacturing costs due to lower raw material costs. Furthermore, this method allows the material melt to be confined within the growth container to minimize contamination from the surroundings, making it possible to achieve high purity single crystals.

[Brief explanation of drawings]

FIG. 1 shows two types of growth containers made of different materials. (a) is the case of quartz glass, and (b) is the case of graphite. The container 1 forms a gap 4 with a partition plate 2 and a spacer portion 3, which is connected to a suction vibro through a constriction 5. FIG. 2 shows an apparatus for manufacturing a thin plate-like single crystal, in which a heater 3 for melting a raw material 2 and a quartz crucible 5 are arranged inside a metal container 1. A seven flange 6 is placed on the top of the metal container 1, and airtightness is maintained by an O ring (a) 7. A small flange 8 is attached to the flange 6, and an O-ring (
b) 9 and O-ring (c) 10 keep the metal container l airtight. A plurality of growth containers 11 are provided in the small flange 8.
is held by the suction pipe 12, and the growth container 1
1 is located at the upper end. Each growth container can be moved up and down independently by a lower drive section 13. At the top of the suction pipe are vacuum cocks (a) 14 and vacuum cocks (b) 15-
Exhaust pipe (a)16. and exhaust pipes (b) 17, each of which is connected to a vacuum pump (a) 18. Further, an exhaust pipe (c) 19 is attached to the 7-lunge 6, which is used for pulp (a) 20. Each is connected to a gas pump 23 and a vacuum pump 22 through a valve (b) 21.

Claims (1)

[Claims] In order to produce a thin plate-shaped single crystal from a material melt, the melt is press-fitted into a plate-shaped container with a gap of a preset thickness using the pressure difference between the inside and outside of the container, and then from one end of the container. A method of producing single crystals by cooling. Silica glass,
Borosilicate glass, aluminum oxide, silicon carbide, boron nitride, ceramic-based electrically insulating materials,
In addition, metal-based electrically conductive materials such as graphite, stainless steel, copper, and platinum are used, and these materials are used alone or in combination to form thin sheets, taking into consideration their wettability with the material melt. It shall have a structure that allows the single crystal to be easily taken out. A method for producing plate-shaped single crystals of metals, semiconductors, insulators, and organic substances from their melts based on these growth containers and production methods.