JP2611336B2 - High dissociation pressure compound semiconductor processing equipment - Google Patents

Description

The present invention relates to a high-dissociation pressure compound semiconductor processing apparatus for pulling up and growing a high-dissociation pressure compound semiconductor single crystal used as a high-resistance substrate for ICs and a doped substrate for an optical device. About.

[Conventional technology]

Conventionally, as a method of pulling and growing this kind of high dissociation pressure compound semiconductor single crystal, a rotation pulling method (Czochralski method) is known. This rotation pulling method,
It is easy to obtain a <100> oriented circular wafer, which is advantageous for the device manufacturing process. In growing a crystal of a high-dissociation pressure substance such as GaAs (gallium arsenide), it is necessary to prevent the escape of the high-dissociation pressure component, and there are roughly two methods. One is boron oxide (B ₂
One method is to cover the melt surface with a liquid such as O ₃ ) and suppress it with the pressure of an inert gas (LEC method). The other is a high dissociation method in which the melt surface has a controlled pressure during the growth operation. It is covered with a pressure component gas atmosphere. Of these, the former method is currently widely used industrially because the apparatus is simple.

However, the conventional LEC method cannot control stoichiometry (stoichiometry) by controlling the vapor pressure.
Since there is a problem that the temperature gradient just above the solid-liquid interface cannot be reduced, it is difficult to improve the quality of the crystal. On the other hand, as means for specifically realizing the second method, for example,
Japanese Patent Application Laid-Open No. 60-51698 discloses an apparatus for sealing a container in a pulling apparatus and for pulling a crystal in a high dissociation pressure component gas atmosphere in which the pressure is precisely controlled.

In the crystal pulling apparatus, as shown in FIG. 3, the container upper part 1 and the container lower part 2 for sealing the high dissociation pressure component gas can be separated from each other by a material which is not exposed to the high temperature gas atmosphere. A liquid or solid seal 4 is provided at the joint 3 and the lower part 2 of the container is pressed against the upper part 1 of the container by a buffer mechanism 6 supported by a push-up shaft 5 to seal the joint 3. ing. With such a structure, a sufficient sealing property of the container can be obtained, and the container can be repeatedly used. Further, a susceptor 8 is attached to the crucible shaft 7 inside the container.
A crucible 9 fixed via the heater is disposed, and the entire container is heated to about 650 to 1300 by a heater 10 disposed outside.
Further, an arsenic gas pressure control furnace 11 is provided on the upper part 1 of the vessel, and the temperature of the arsenic gas pressure control furnace 11 is controlled to be constant and lower than any other part of the sealed container.
By condensing 12, the arsenic pressure in the sealed container is controlled, and the pulling shaft 13 is pulled up while rotating the crucible shaft 7 and the pulling shaft 13 together, so that the single crystal 15 is separated from the melt 14 in the crucible 9. It is designed to be raised. Note that reference numeral 16
Is a seal made of a liquid (B ₂ O ₃ ), and 17 is a translucent rod.

Unlike the conventionally known quartz sealed container, the crystal pulling device is extremely easy to separate and adhere to the container, making it possible to use it repeatedly, and to manufacture large-diameter ingots. Has become enduring industrial use.

[Problems to be solved by the invention]

By the way, since the apparatus for pulling the crystal has a divided type of sealed container, the container can be used repeatedly, but one of the main points of the technology is a method of sealing the divided portion (joining portion 3). In the case where a liquid is used as a sealing material for the joint 3, a liquid of one or a mixture of boron oxide, barium chloride, sodium fluoride, sodium chloride, potassium chloride, and calcium chloride is conventionally known. (Metz, JAP 33 , 2016 (1962), Mullin
JBetal J. Phys. Chem. Solids 26 , 752 (1965)). These materials are excellent materials because they do not cause contamination of impurity elements from the viewpoint of high crystal purity,
The problem is poor operability. That is, the container is sealed by immersing the lower end of the container upper portion 1 in the liquid seal material held in the liquid seal material holding portion 3, but the seal of this structure has a difference in pressure inside and outside the container. At this time, since the liquid sealing material overflows and loses arsenic, it is necessary to pay close attention to the balance of the pressure inside and outside the container. In particular, there is a problem in that the internal arsenic pressure at the time of temperature rise leading to the melting of the raw material and at the time of temperature fall after completion of the pulling is greatly changed, and it is necessary to change the pressure sufficiently slowly so that the pressure inside and outside the container is always balanced. Among them, there is a problem that if the imbalance between the pressure inside and outside the container at the time of raising the temperature is large, the stoichiometric control may be fatally failed. The second problem of the liquid sealing material is that it is destructive depending on the material because it has good wettability with many materials and has a high coefficient of thermal expansion at a temperature below the freezing point. For example, if pBN (pyrolytic boron nitride) is used as a sealed container material, the pBN of the sealing part should be
Peeling from the material occurs, eventually leading to the destruction of the pBN material. This is a major drawback from the industrial point of view of reducing product prices.

The present invention has been made in view of the above circumstances, and aims to maintain high purity of crystals,
An object of the present invention is to provide a high-dissociation pressure compound semiconductor processing apparatus which has good operability and does not cause destruction at a joint portion of a container.

[Means for solving the problem]

To achieve the above object, the present invention provides a method for sealing silicon oxide, aluminum nitride, or silicon nitride at a joint of a detachable sealed container filled with a high dissociation pressure component gas.
Boron nitride, aluminum oxide, zirconia, silicon carbide,
One or more powders of titanium carbide, titanium nitride and graphite, and a liquid consisting of a mixture of one or more of boron oxide, barium chloride, sodium fluoride, sodium chloride, potassium chloride and calcium chloride It is provided with a configured sealing material.

(Operation)

In the high-dissociation pressure compound semiconductor processing apparatus of the present invention,
Silicon oxide, aluminum nitride, boron nitride having a coefficient of thermal expansion equal to or close to the coefficient of thermal expansion of the sealed container material;
Add a liquid consisting of one or more of boron oxide, barium chloride, sodium fluoride, sodium chloride, potassium chloride, and calcium chloride to aluminum oxide, zirconia, silicon carbide, titanium carbide, titanium nitride, and graphite powder. By using the sealing material, the apparent thermal expansion coefficient after the liquid has solidified can be made substantially equal to that of the above-mentioned sealed container material. Thereby, breakage of the joint of the sealed container can be prevented. Further, the fluidity of the sealing material is also reduced by the added powder, and the escape of the high dissociation pressure component gas due to the overflow of the sealing material can be prevented. That is, at a high temperature, as shown in FIG. 1, when the powder 21 in the sealing material 20 hinders the flow of the liquid 22, and when the temperature becomes low and the liquid 22 in the sealing material 20 solidifies, as shown in FIG. Due to the difference in thermal expansion coefficient between the added powder 21 and the solidified liquid 22, the liquid 22 is finely divided, but the contraction rate of the sealing material 20 can be apparently set to a value substantially equal to the contraction rate of the material of the container lower part 2. Therefore, the joint of the container is not broken.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS.

In order to grow a GaAs single crystal, a pulling device having a seal as shown in FIG. 3 was used. Then, molybdenum is used for the upper container 1 and pB is used for the lower container 2.
N (pyrolytic boron nitride) was used. At this time, in consideration of the thermal expansion coefficient of pBN, boron nitride is used as the powder 21 to be added,
B ₂ O ₃ with (boron oxide) as the liquid mixture 22, and a sealing member 20 of the joint portion 3 shown in FIG. 1 and FIG. 2.

Then, after the arsenic gas pressure was set to 1 atm, the GaAs melt 14 was synthesized in the crucible 9 and the crystal rotation was 10 rpm, the crucible rotation was 10 rpm,
When the lifting was performed at a lifting speed of 5 mm, arsenic did not escape from the sealed container, and peeling of the lower portion 2 made of pBN was also prevented. The grown single crystal 15 was stoichiometric.

In this embodiment, the sealing of the joint 3 of the sealed container has been described. However, the present invention is not limited to this, and can be applied to, for example, a rotary seal.

〔The invention's effect〕

As described above, the present invention relates to a method for sealing silicon oxide, aluminum nitride, boron nitride, aluminum oxide, zirconia at a joint of a detachable sealed container filled with a high dissociation pressure component gas, and sealing the joint. , Consisting of a mixture of one or more powders of silicon carbide, titanium carbide, titanium nitride, graphite, and one or more of boron oxide, barium chloride, sodium fluoride, sodium chloride, potassium chloride, and calcium chloride Since a sealing material made of a liquid is provided, silicon oxide, aluminum nitride, boron nitride, aluminum oxide, zirconia, silicon carbide having a thermal expansion coefficient equal to or close to the thermal expansion coefficient of the sealed container material, Boron oxide, barium chloride, sodium fluoride, sodium chloride Lithium, potassium chloride, by adding a liquid comprising a mixture of one or several of calcium chloride to form a sealing material, the apparent coefficient of thermal expansion after the liquid is solidified, and that of the sealed container material It can be made substantially equal, so that the joint of the sealed container can be prevented from being broken, and the added powder reduces the fluidity of the sealing material, and the leakage of the high dissociation pressure component gas due to the overflow of the sealing material. Therefore, there is an excellent effect that the operability of the sealing material is good and high purity of the crystal can be maintained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a joint of a sealed container showing an embodiment of a high-dissociation pressure compound semiconductor processing apparatus of the present invention, FIG. 2 is a cross-sectional view of the case where the joint of the sealed container is separated, and FIG. It is a conceptual diagram which shows an example of a dissociation pressure compound semiconductor processing apparatus. 1 ... upper container, 2 ... lower container, 3 ... joint, 15 ... single crystal, 20 ... sealing material, 21 ... powder, 22 ... liquid.

Claims (1)

(57) [Claims] 1. A high dissociation pressure compound semiconductor processing apparatus for pulling up a high dissociation pressure compound semiconductor single crystal in a dividable sealed container filled with a high dissociation pressure component gas. Silicon oxide, aluminum nitride, boron nitride, aluminum oxide, zirconia, silicon carbide, titanium carbide, titanium nitride,
A sealing material composed of one or several kinds of graphite powder and a liquid composed of a mixture of one or several kinds of boron oxide, barium chloride, sodium fluoride, sodium chloride, potassium chloride, and calcium chloride is provided. And a high-dissociation pressure compound semiconductor processing apparatus.