JPS58130194A - Manufacture of silicon single crystal - Google Patents

Abstract

PURPOSE:To obtain a silicon single crystal of high quality without growing the deposited corner by growing a silicon single crystal by a pulling method, separating the crystal from the melt at once, and treating under heat it at a high temp. CONSTITUTION:Polycrystalline silicon is filled into a crucible 1 and melted by heating with a heater 2. By pulling up a seed crystal 3, a single crystal ingot 4 is grown while maintaining the relative position of the heater 2 to the surface of the melt. After finishing the crystal growth, the resulting single crystal ingot 4 is positioned just above the surface of the residual melt 5, and the heater 2 is moved upward to the position 2'. The ingot 4 is heated at 1,200 deg.C- the m.p. of silicon for a prescribed time with the heater 2. The power supply is then cut, and the single crystal is pulled up and rapidly cooled. By the heat treatment a silicon single crystal of high quality suitable for a semiconductor integrated circuit, etc. is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing high quality silicon single crystals used in semiconductor integrated circuits and the like.

Conventionally, a silicon single crystal grown from silicon melted in a quartz crucible by the Czochralski (C''Z) method has been used as a base plate material for integrated circuits and large-scale integrated circuits.This CZ single crystal The problem with using 1 is that the oxygen eluted from the quartz crucible into the silicon melt dissolves into the crystal, and oxygen precipitates during cooling during crystal pulling or heat treatment during the element fabrication process. Yes, this precipitate causes leakage current and is undesirable.

In addition to the OZ method, there is also a floating zone (FZ) method as a method for manufacturing silicon single crystals.

Since the single crystal made by this method has a low oxygen content, it can withstand heat treatment of 100°C or higher with a wafer diameter of 9.
Dislocations easily occur, which is not desirable.

The above is due to the structure of the crystal growth furnace with a built-in heater.
This is thought to be due to the difference in thermal history in the longitudinal direction of the crystal ingot. Therefore, in order to confirm this, the temperature distribution during crystal pulling was measured using a thermocouple. The results are shown in FIG. Normally, the pulling rate during crystal growth is 1 wx/1yr
It can be seen from FIG. 1 that the growing crystal slowly passes through the region of 600 to 800° C., which is the temperature of nucleation of precipitates, and the region of 1,000 to 1,100° C., which is the temperature of nucleus growth.

In fact, when subjected to such low-temperature heat treatment for a long time, a diode made using a crystal cut from the upper part of the ingot has a large leakage current, whereas a diode made using a crystal cut from the upper part of the ingot, which has been subjected to low-temperature heat treatment for a short time, has a large leakage current. The leakage current of it made is small.

On the other hand, silicon wafers are heated to over 1300℃.

It is known that the growth of precipitated nuclei is inhibited by rapid cooling after heat treatment for about 30 minutes, and that oxygen precipitation hardly occurs in subsequent normal heat treatment. 16 like this
In order to maintain a high-purity atmosphere during heat treatment at temperatures as high as 00℃,
When done inside a quartz tube.

Devitrification of quartz tube 1 bent, severe wear and tear.

In view of one or more points, the present invention is characterized in that after crystal growth is performed in a single crystal growth furnace equipped with a built-in heater, high-temperature heat treatment is performed in the same growth furnace while the ingot is in the form of an ingot.

The present invention will be explained in detail below using examples.

Example As shown in FIG. 2, a quartz crucible 1 with a diameter of 606 m and a height of 50 cm was filled with polycrystalline silicon, and after replacing the inside of the furnace with gas A, the polycrystalline silicon was heated and melted with a heater 2. do. While rotating the silicon melt and the seed crystal 6, the seed crystal 3 is pulled up and the single crystal ingot 4 is grown under normal conditions.The melt surface decreases as O precipitates grow, but the relationship between the heater 2 and the melt surface Keep the relative position approximately constant.

After the crystal growth is completed, the heater 2 is located approximately at the dotted line position in the figure.

At this point, the single crystal ingot 4 is placed directly above the liquid level of the residual melt 5, and the heater 2 is moved upward to the highest position relative to the quartz crucible 1, that is, the position 2 indicated by the solid line. ’.

From the results shown in FIG. 1, the temperature of the crystal in the upper part of the ingot ♦ is equal to the temperature of the atmospheric gas, so the power of the heater is adjusted so that the temperature in the upper part of the ingot becomes 1300°C. If the power of the heater 2 is insufficient due to the length of the growing crystal 4, etc., an auxiliary heater 6 is installed above the heater 2 for the growth furnace as shown in FIG. I will do it so that it becomes true. Auxiliary heaters, for example.

It is made of graphite and has a capacity of 3oV and 500A. After heat treatment at this temperature for about 30 minutes, the power to the heater is turned off, and the crystal is pulled up at a speed of 5 to 106 m/win and rapidly cooled. This heat treatment must be carried out at a temperature of 1,200° C. or higher, which is the extinction temperature of defect nuclei caused by oxygen in the silicone, and within a temperature range that does not exceed the melting point of silicon.

The leakage current of the diode manufactured from the wafer cut from the single crystal obtained as described above was extremely small.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the temperature distribution during crystal pulling in a pulling method single crystal growth furnace equipped with a built-in heater, and FIG. 2, FIG. 3, and FIG. Four times. In fig. 1 Crucible 2... Heater 6 Seed crystal 4... Single crystal ingot 5...
Residual melt 6... Junnosuke Nakamura, patent attorney representing the auxiliary heater

Claims (1)

[Claims] 1. In a method for producing a silicon single crystal using a pulling single crystal growth furnace with a built-in heater, the single crystal obtained immediately after single crystal growth is separated from the melt and heated to a temperature of 1200°C or higher and lower than the silicone point. A method for producing a silicon single crystal, characterized by heat treatment at a temperature range for a predetermined period of time.