JPS6117489A - Production of silicon single crystal - Google Patents

Abstract

PURPOSE:A single crystal is pulled up from the starting material which is melted in a crucible which has inner walls made of nonoxides to enable easy product of silicon single crystals of a large diameter and a low oxygen content. CONSTITUTION:For example, a quartz crucible 10 is covered with Si3N4 layer of about 30mu 11. The Si3N4 layer 11 can be formed, e.g., by the low-temperature plasma method. SiC may be used instead of Si3N4. The resultant Si3N4-coated quartzd crucible 10 is used to pull up a single crystal from the starting material melted in the crucible whereby a single crystal of Si is obtained. Since the starting material is melted in a crucible of nonoxide materials, the dissolution of oxygen from the crucible is prevented, resulting in the formation of a single crystal of low oxygen concentration.

Description

[Detailed description of the invention] 〔Technical field〕 This invention relates to a method for producing silicon single crystals.

[Prior art]

Conventionally, methods for manufacturing silicon single crystals include the Chmichralski method (CZ method), in which the tip of a seed crystal with the desired crystal orientation is attached to a solution of a crystal raw material, and the single crystal is grown while being gradually pulled up. A float zone method in which a polycrystalline silicon rod is held vertically and its lower axis is held by a seed crystal, and the polycrystalline silicon in the contact area is melted using high-frequency boiling, and the melted zone is moved to single-crystallize the silicon. (F
Z method) etc. are known. Among these, the most common CZ
Explain the law.

Figure 1 shows the pulling of a 7-licon single crystal using the C2 method.
FIG. 2 is a sectional view of a main part of the device.

As shown in FIG. 1, a quartz crucible 3 for melting crystal raw materials is placed inside a reaction vessel 1 made of quartz or the like, and a shaft 4
It is configured to be supported by and rotated in the direction of the arrow. A heater 5 made of graphite is placed around the crucible 3 to uniformly heat the crucible 3. When the crystal raw material is dissolved in a non-oxidizing atmosphere such as argon, the silicon seed crystal 7 attached to the holder 6 is immersed in the solution 2.

In order to grow a silicon single crystal using the pulling device configured in this way, the solution 2 in the crucible 3 must be heated to about 1500 ml.
While keeping the temperature at a predetermined temperature of .degree. C., the tip of the seed crystal 7 is immersed and rotated, and at the same time, the crucible 3 is also rotated. Then, by pulling up the holder 6 while rotating it and gradually lowering the temperature of the crucible 3, a silicon single crystal 8 having a desired diameter can be obtained.

However, the silicon single crystal obtained in this way contains 1 and S i 021 melted from the quartz crucible 3.
Generally, carbon contains a high concentration of oxygen of 10 to 20 x 1017/d. When forming a semiconductor element using a silicon substrate containing this high concentration of oxygen,
In the silicon crystal by a heat treatment process of about 1200℃,
This has the disadvantage that crystal defects caused by oxygen occur, deteriorating the electrical characteristics of the device.

To obtain silicon single crystals with low oxygen concentration, magnetic field pulling method (
The MCZ method) and the FZ method are used, but they have the disadvantage that it is difficult to produce a silicon single crystal with a large diameter and is expensive.

[Purpose of the invention]

An object of the present invention is to provide a method for eliminating the above-mentioned drawbacks and easily producing a silicon single crystal having a large diameter and a low oxygen concentration.

[Structure of the invention]

The method for producing a silicon single crystal of the present invention is a method for producing a silicon single crystal in which a single crystal is pulled and grown from a crystal raw material dissolved in a crucible, and the method is a method for producing a silicon single crystal, in which a crucible having at least an inner wall made of a non-oxide is used to produce a silicon single crystal. It dissolves raw materials.

According to the present invention, since the raw crystal material is melted in a non-oxide crucible, there is no dissolution of oxygen from the crucible, and therefore a low-oxygen silicon single crystal can be obtained.

[Explanation of Examples]

Next, embodiments of the present invention will be described using the drawings.

FIG. 2 is a sectional view of a crucible for explaining one embodiment of the present invention.

In FIG. 2, the surface of the quartz crucible 10 has a thickness of about 3
It is covered with a 0 μm silicon nitride (SisN4) layer 11. This 5isN layer 11 can be formed using, for example, a low temperature plasma method. Silicon carbide' (8iC) may be grown and used instead of 8isN.

Using the quartz crucible 10 whose surface was covered with the 8isNa layer 11 in this manner, an apparatus similar to that shown in FIG. 1 was constructed. Then, a silicon single crystal with a diameter of approximately 125 meshes was manufactured using the C2 method, which includes the same steps as the conventional method. The results of measuring the oxygen concentration of multiple manufactured silicon single crystals using an infrared absorption method show that the oxygen concentration is all 1 x 1 (17/
cdt or less, and it was found that there was no dissolution of oxygen from the crucible 10.

As described above, according to the present invention, a silicon single crystal with a low oxygen concentration can be easily manufactured in a process similar to the conventional C2 method, so that a rectifying element and a transistor substrate for high breakdown voltage power can be obtained at low cost. Furthermore, IC substrates with low oxygen concentrations are less likely to generate crystal defects due to heat cycles, and are therefore ineffective in improving IC yield and reliability.

In the above example, a crucible whose surface was covered with 8taNiffi was used, but a crucible made by forming and firing a powder of a ceramic material that does not contain oxygen, such as 8i s Na or 8iC, would also have low oxygen content. A high concentration silicon single crystal can be obtained.

〔Effect of the invention〕

As described in detail above, according to the present invention, silicon single crystals having a large diameter and a low oxygen concentration can be easily manufactured, which is highly effective in manufacturing rectifiers, ICs, and the like.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of an apparatus for explaining the CZ method, and FIG. 2 is a sectional view of a crucible for explaining one embodiment of the present invention. 1...Reaction container, 2...Dissolution liquid, 3.
・・・・・・Crucible, 4・・・・Axis, 5・・・・・・
Heater, 6... Holder, 7... Seed crystal, 8... Silicon single crystal, 10... Crucible, 11... Sj , f'L layer.

Claims (1)

[Claims] A method for producing a silicon single crystal in which the single crystal is grown by pulling it from a crystal raw material dissolved in a crucible, characterized in that the crystal raw material is melted using a crucible whose inner wall is made of a non-oxide. Production method.