JP2002160911A - METHOD FOR MANUFACTURING InP POLYCRYSTAL - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an InP polycrystal with high productivity and high purity. SOLUTION: In the method for manufacturing the InP polycrystal by a horizontal boat method, a graphite vessel with an impurity concentration of 400 ppm or less is used as a vessel where In is accommodated, a transfer speed of the graphite vessel is set on the range of 20 to 50 mm/h and a high-frequency induction heating is used for heating the graphite vessel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing an InP polycrystal used as a raw material for producing an InP single crystal or the like.

[0002]

2. Description of the Related Art Since red phosphorus used for producing InP crystals has a high vapor pressure, it is difficult to directly grow InP single crystals using red phosphorus. For this reason, it is common practice to first produce an InP polycrystal using red phosphorus and produce an InP single crystal using the InP polycrystal as a raw material.
The horizontal boat method is mainly used for the synthesis of InP polycrystal. The indium and red phosphorus put in the boat are vacuum-sealed in a quartz ampule and placed in a high-pressure horizontal boat furnace.
The red phosphorus portion in the quartz ampule is heated to increase the phosphorus vapor pressure in the quartz ampule. At this time, the outside of the quartz ampule inside the horizontal boat furnace was
It is pressurized with an inert gas or the like so that the vapor pressure of red phosphorus in the quartz ampule and the external pressure of the ampule are balanced.
A part of the boat containing indium is heated to near the melting point of InP, and the indium reacts with the phosphorus vapor to form InP.
Produce polycrystals. At this time, move the quartz ampoule,
It is common to produce InP polycrystals by passing a high temperature portion from the end of the boat containing indium.

[0003]

In order to produce a high-purity InP single crystal, it is necessary to use a high-purity InP polycrystal as a raw material. However, conventionally, quartz has been used as a boat in the production of InP polycrystals by the horizontal boat method. However, Si contained in quartz tends to be mixed as impurities into the InP crystals, and the purity of the produced InP polycrystals is reduced. Was. Also, in order to prevent Si from being mixed into the InP polycrystal,
Although the use of an h-BN boat has been used, this can prevent the incorporation of Si, but may introduce other impurities contained in the h-BN, and the h-BN boat is insulative. Therefore, induction heating such as high frequency cannot be used,
Since the heating temperature distribution of the boat becomes non-uniform, there is a problem that the composition ratio of In and P deteriorates. Also h-B
Since the boat made of N is more expensive than quartz or the like, the production cost of the InP polycrystal has been increased.

An object of the present invention is to solve the above problems and to provide a method for producing an InP polycrystal having high purity and low production cost.

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, it has been found that the use of a graphite vessel for a boat for containing In prevents the incorporation of impurities into the InP polycrystal. It has been found that high-purity InP polycrystals can be produced, and that graphite can be induction-heated, so that the raw materials can be uniformly heated and high-quality, low-cost InP polycrystals can be produced. Completed. That is, according to the present invention, [1] In contained in a container made of graphite (hereinafter referred to as a graphite container) is enclosed in one ampule together with a phosphorus-containing substance, and the ampule is placed in a synthesis furnace having a temperature distribution inside. While heating the graphite container in the ampoule while moving it through the high temperature area in the synthesis furnace.
A method for producing an InP polycrystal for producing a P polycrystal, [2] a method for producing an InP polycrystal according to [1], wherein the impurity concentration of the graphite container is 400 ppm or less;
[3] The method for producing an InP polycrystal according to [1] or [2], wherein the impurity concentration of the graphite container is 20 ppm or less, [4] The impurity concentration of the graphite container is 5 ppm.
Any one of [1] to [3], characterized in that:
Item 5. The method for producing an InP polycrystal according to item [5], wherein the moving speed of the graphite container in the high temperature region in the synthesis furnace is 20 to 50 mm /
The method for producing an InP polycrystal according to any one of [1] to [4], wherein the high frequency induction heating is used for heating the graphite container. The present invention relates to a method for producing an InP polycrystal according to any one of [1] to [5].

[0005]

DETAILED DESCRIPTION OF THE INVENTION The InP polycrystal of the present invention is manufactured by a horizontal boat method. More specifically, a substance containing phosphorus and In contained in a graphite container are placed in, for example, a quartz ampoule, and this is heated from the outside to cause a reaction between In and P to produce I.
Produce nP polycrystal. When graphite is used for the In storage container for the production of InP polycrystal, conventionally used quartz or h
-Pb is easier to purify the InP crystal compared to -BN.
The concentration of impurities mixed in the nP crystal can be reduced. The graphite container used in the present invention is preferably of high purity, specifically, a graphite container having an impurity concentration of 400 ppm or less, more preferably an impurity concentration of 2% after a purification treatment.
0 ppm or less graphite container, most preferably impurity concentration 5
Use a graphite container of less than ppm.

As the phosphorus-containing substance, yellow phosphorus, metallic phosphorus, red phosphorus and the like can be used, and among them, red phosphorus is particularly preferable.

FIG. 1 is a schematic view showing an example of a quartz ampule used in the present invention. Inside the quartz ampule 1, a red phosphorus ingot 3 is placed, and further, quartz wool 4 is placed for the purpose of a diffusion barrier for maintaining a phosphorus vapor pressure in the synthesis reaction section. The size of the quartz ampule is preferably 80 to
120 mm, and the length is 700-1200.
mm, the thickness is in the range of 3 to 5 mm, and the amount of red phosphorus contained in the quartz ampoule is preferably 600 to
Within the range of 1200 g, the amount of quartz wool is preferably
It is in the range of 5 to 20 g.

Next, the In ingot 5 is put into a graphite container 6, covered with a graphite lid 7, put into a quartz ampule 1, a quartz cap 2 is fitted to the open end side of the quartz ampule 1, and connected to a vacuum pump. While the inside is evacuated, the quartz cap 2 and the quartz ampule 1 are sealed with a burner to produce a quartz ampule.

The graphite container contained in the quartz ampoule is preferably cylindrical and has a size preferably of 50 mm diameter.
１００100 mm, and the length is 300〜600.
mm, the thickness is in the range of 4-8 mm. Further, the amount of the In ingot to be put in the graphite container is preferably in the range of 2000 to 4000 g.

The quartz ampoule is put into, for example, a furnace shown in FIG. 2 and heated to react In and P to produce an InP polycrystal. In the furnace shown in FIG. 2, it is preferable that the heating furnace 9, the heating furnace 10, and the high-frequency induction heating furnace 11 form a temperature distribution as shown in FIG. The horizontal axis in FIG. 3 indicates each part in the synthesis furnace 8. That is, Ti on the horizontal axis in FIG.
n indicates the position of the heating furnace 1 (FIG. 9), Tm indicates the position of the high-frequency induction heating furnace 11, and Tp indicates the heating furnace 2 (FIG. 1).
0). The temperature on the vertical axis in FIG. 3 is an arbitrary value, and the higher the temperature, the higher the temperature. That is, T on the vertical axis of FIG.
“in” indicates the heating temperature of the heating furnace 9, “Tm” indicates the induction heating temperature of the graphite container 6 by the high-frequency induction heating furnace 11, and “Tp” indicates the heating temperature of the heating furnace 10.

By heating the red phosphorus in the heating furnace 10, the inside of the quartz ampoule is filled with a predetermined phosphorus vapor pressure, and the high-frequency induction heating furnace 11 heats In to a temperature around the melting point of InP (about 1062 ° C.). InP polycrystal is synthesized.
At this time, the temperature of the heating furnace 9 needs to be set higher than that of the heating furnace 10 so that the phosphorus vapor does not re-aggregate. The Tin temperature in this case is preferably 600 to 800 ° C.
, More preferably within the range of 650 to 750 ° C, the Tm temperature is preferably within the range of 1000 to 1300 ° C, more preferably within the range of 1050 to 1200 ° C, and the Tp temperature is preferably It is in the range of 550-590 ° C, more preferably in the range of 560-580 ° C. The Tm can be heated by resistance heating or the like without using high-frequency induction heating. However, when the graphite container of the present invention is used, the high-frequency induction heating allows the inside of the container to be heated more uniformly and high purity. Is preferable because it enables highly efficient production of InP polycrystal.

In the furnace, it is preferable to keep the pressure difference constant by the pressure controller 14 so as not to generate a pressure difference inside and outside the quartz ampule.
It is within the range of 25 MPa, and it is preferable to use nitrogen gas for controlling the pressure.

The actual crystal growth is performed in the following procedure. FIG.
1. A quartz ampoule enclosing the raw material shown in FIG. 1 is installed in the furnace shown in FIG. 1, and the heating furnace 9, the heating furnace 10, and the high-frequency induction heating furnace 11 are formed with the temperature distribution shown in FIG.
The quartz ampoule in FIG. 2 is moved by the drive shaft 12 in the direction of the arrow shown in FIG. 2, and the right to left ends of the graphite container in the quartz ampule are heated by passing through a high-frequency furnace part. The moving speed of the quartz ampule depends on the capacity of the furnace, the size of the quartz ampule, and the amount of the raw material in the ampoule, but is preferably in the range of 20 to 50 mm / hour, more preferably in the range of 20 to 30 mm / hour. Is within. When the moving speed is higher than the above range, an unsynthesized portion of In and P is found in a part of the obtained polycrystal, and the purity of the product is deteriorated. On the other hand, if the moving speed is slower than the above range, it takes a long time to perform synthesis, and the productivity is reduced.

After the graphite container is heated up to the left end, the movement of the quartz ampule is stopped, and the inside of the furnace is gradually cooled. After that, the furnace pressure was set to the atmospheric pressure, the furnace was opened, and the quartz ampule was taken out. The quartz cap portion of the quartz ampule is cut, the graphite container is taken out, and the synthesized InP polycrystalline ingot is taken out of the graphite container.

[0015]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

(Embodiment) FIG.
A red phosphorus ingot 3 having a weight of 0.8 kg and a purity of 99.999% was placed in a quartz ampoule 1 having a size of 8 mm, an inner diameter of 72 mm and a length of 1000 mm, and about 10 g of quartz wool 4 was further added. Next, an indium ingot 5 weighing 2.4 kg was placed therein, and a cylindrical graphite container 6 having both ends sealed with caps 7 was placed therein. The impurity concentration of the graphite container is 5 ppm or less by the purification treatment, and the size of the graphite container is 65 m in diameter.
m, inner diameter 75 mm, and length 490 mm. A quartz cap 2 was fitted to the open end side of the quartz ampule, and the quartz cap and the quartz ampule were sealed with a burner while connected to a vacuum pump and the inside of the quartz ampule was evacuated.

Next, the quartz ampoule was placed in the furnace shown in FIG.
1 has a temperature distribution as shown in FIG. In addition, Tin was set to 650 ° C., Tm was set to 1200 ° C., and Tp was set to 570 ° C., and the inside of the furnace was set to 19 MPa so that the pressure inside and outside the quartz ampoule was almost constant by nitrogen gas. Fig. 2 quartz ampule
The quartz ampule was moved at a speed of 22 mm / hour in the direction indicated by the arrow in the middle, the movement was stopped when the quartz ampoule was passed from the right end to the left end through the high-frequency induction heating furnace part, and the inside of the furnace was gradually cooled and depressurized. After the furnace pressure was set to atmospheric pressure, the furnace was opened and the quartz ampule was taken out. The quartz cap portion of the quartz ampule was cut, the graphite container was taken out, and the synthesized InP polycrystalline ingot was taken out of the graphite container.

The obtained InP polycrystalline ingot was cut into a plurality of pieces, and the cut surface was visually checked. As a result, InP was synthesized in almost the entire region except for a few mm of the end of the ingot, and no unsynthesized portion was observed. FIG. 4 shows the result of an impurity analysis performed on a sample collected from the present polycrystal, and an InP polycrystal having a low impurity concentration was obtained.

Comparative Example Using the same apparatus and raw materials as in the example, only the indium container was changed from a graphite container to a p-BN container. Polycrystalline synthesis was performed at the same temperature distribution as in the example and at a driving speed of 22 mm / hour. In obtained
The P polycrystalline ingot was cut into a plurality of pieces, and the cut surface was visually checked. As a result, an unsynthesized portion of InP was found in about 40% of the sections. This is presumably because the use of a boat made of p-BN resulted in insufficient heating of the boat and the reaction between In and P did not proceed sufficiently. In addition, FIG. 4 shows the result of an impurity analysis performed on a sample collected from the present polycrystal, and the impurity concentrations of Al, Si, and As were higher than those of the example. These are considered to be impurities mixed from the p-BN boat.

[0020]

According to the present invention, a high-purity InP polycrystal can be produced with high productivity. In particular, according to the present invention, the melting of the In ingot can be performed by high-frequency induction heating, and uniform heating can be performed even when the moving speed of the quartz ampule is increased, so that higher productivity can be realized. Was.

[Brief description of the drawings]

FIG. 1 shows a cross-sectional view of a quartz ampule of the present invention.

FIG. 2 shows an example of a sectional view of an apparatus for carrying out the present invention.

FIG. 3 shows a temperature distribution in the synthesis furnace shown in FIG.

FIG. 4 is a graph showing impurity concentrations in InP crystals obtained in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Quartz ampoule 2 Quartz cap 3 Red phosphorus ingot 4 Quartz wool 5 Indium ingot 6 Graphite container (body) 7 Graphite container (lid) 8 Synthesis furnace 9 Heating furnace 10 Heating furnace 11 High frequency induction heating furnace 12 Drive shaft 13 Thermocouple 14 Pressure Control device

Claims (6)

[Claims] 1. In a container containing graphite (hereinafter referred to as a graphite container), In is enclosed in one ampule together with a phosphorus-containing substance, and the ampule is placed in a synthesis furnace having a temperature distribution therein. A method for producing an InP polycrystal, which produces an InP polycrystal while heating and moving a graphite container portion in an ampule through a high-temperature region in a synthesis furnace. 2. The method according to claim 1, wherein the impurity concentration of the graphite container is set to 400 ppm or less. 3. The InP according to claim 1, wherein the impurity concentration of the graphite container is 20 ppm or less.
Polycrystalline manufacturing method. 4. The method for producing an InP polycrystal according to claim 1, wherein the impurity concentration of the graphite container is 5 ppm or less. 5. The InP multi-layer according to claim 1, wherein a moving speed of the graphite container in the high temperature region in the synthesis furnace is within a range of 20 to 50 mm / hour. Method for producing crystals. 6. The method for producing an InP polycrystal according to claim 1, wherein high-frequency induction heating is used for heating the graphite container.