JP2635456B2 - Silicon single crystal pulling method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention suppresses the occurrence of pinholes in a single crystal when pulling a silicon single crystal by the Czochralski method, eliminates initial operation troubles, and reduces the carbon concentration in the single crystal. The present invention relates to a method for pulling a silicon single crystal, which can reduce the temperature.

[0002]

2. Description of the Related Art A case of manufacturing a silicon single crystal rod by the Czochralski method will be described. A quartz crucible held by a graphite susceptor is provided substantially at the center of a pulling chamber (metal chamber), and the center of the bottom of the graphite susceptor is provided. Is supported from below by a rotatable and vertically movable support shaft. A raw material polycrystalline silicon is charged into a quartz crucible, and the polycrystalline silicon is heated and melted by a graphite heater surrounded by a heat insulator to form a melt.
The pulling room has an opening in the center of the ceiling, passes through a sub-chamber connected to it, descends a rotatable and vertically movable pulling shaft holding a seed crystal at the tip, and immerses it in the melt When the seed crystal is pulled while rotating the pulling shaft and the quartz crucible, a single crystal rod can be grown below the seed crystal. During this time, a protective gas such as argon gas is introduced from the upper part of the sub-chamber, and is discharged from the outlet at the lower part of the pull-up chamber.

[0003] In recent years, with the increase in the amount of charge, the hot zone (such as a pulling furnace) has been increased in size.
100-300 from operation under furnace pressure of about mbar
Operation under a slightly higher furnace pressure of mbar is becoming mainstream. However, when the furnace internal pressure increases, the following problem occurs.

[0004] Since it is difficult for bubbles contained in the melt to flow out of the melt, the bubbles are taken into the crystal, and a defect such as a pinhole with a hole in the crystal is likely to occur.

[0005] Since the volatilization of impurities and bubbles in the melt is suppressed, the number of dislocations in the crystal caused by the impurities and bubbles increases, and initial troubles increase.

While the temperature is extremely high during melting, carbon from a heater or the like is likely to be generated in the gas. However, when the furnace pressure is high and the gas circulation in the furnace is poor, the carbon is mixed into the melt and enters the crystal. It becomes easy to be taken in, and the carbon concentration in the crystal tends to increase.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and pulls a silicon single crystal for a substrate for manufacturing a semiconductor integrated circuit device by the Czochralski method. It is an object of the present invention to provide a method for pulling a silicon single crystal that can suppress the occurrence of pinholes in the single crystal, eliminate initial operation troubles, and reduce the carbon concentration in the single crystal. And

[0008]

In order to solve the above-mentioned problems, in the method for pulling a silicon single crystal of the present invention, a polycrystalline silicon raw material is melted at a furnace pressure of 5 to 60 mbar, and a furnace having a furnace pressure of 100 mbar or more is melted. The pulling of a silicon single crystal is performed at an internal pressure.

The furnace pressure at the time of pulling the single crystal is 1
Intermediate pressures of 00 to 300 mbar can be employed.

The furnace pressure at the time of pulling the single crystal is 1
A normal pressure of 013 mbar or higher or a higher pressure can also be employed.

If the pressure at the time of melting the above-mentioned polycrystalline silicon raw material is less than 5 mbar, the quartz crucible will be greatly deteriorated, and if it is more than 60 mbar, the object of the present invention cannot be achieved.

[0012]

When the polycrystalline silicon raw material is melted, the gas contained in the raw material itself or the quartz crucible melts into the melt as bubbles. When the furnace pressure during melting is reduced under a reduced pressure of 5 to 60 mbar, the buoyancy of bubbles in the melt increases and the solubility of gas decreases, compared with the case where the furnace pressure is reduced under a furnace pressure of 100 mbar or more. Are easily volatilized, the amount of bubbles contained in the melt during crystal growth is reduced, and the incidence of pinhole defects caused by the inclusion of bubbles in the crystal is reduced.

When the furnace pressure during melting is reduced under a reduced pressure of 5 to 60 mbar, volatilization of not only bubbles but also impurities such as Na is promoted. Accordingly, dislocation of the crystal due to bubbles and impurities is reduced.

The SiO, which is constantly evaporated from the melt surface, is carried by the gas flow of the carrier gas Ar and reacts with the graphite component (especially the heater) which is red-heated to generate CO gas. In a state where the furnace pressure is higher than 100 mbar, the gas flow becomes worse, and the occurrence rate of carbon concentration defects generated by dissolving this CO gas in the silicon melt and incorporating it into the crystal increases.

The CO gas dissolved in the silicon melt is:
The higher the temperature of the graphite part, the more likely it is to generate, and usually most of the CO gas dissolved in the silicon melt is during melting where the temperature of the graphite part is the highest. The furnace pressure during melting, in which CO gas is easily generated, is 5-6.
When performed under reduced pressure of 0 mbar, the gas flow is improved,
Since the incorporation of CO gas into the melt can be suppressed, the defective rate of carbon concentration in the crystal decreases.

In order to carry out the present invention for reasons such as oxygen concentration and crystallinity, the furnace pressure during melting of the polycrystalline silicon raw material should be 5-6.
For 0 mbar, the furnace pressure when pulling a single crystal is 100 to 3
The two combinations of 00 mbar or normal pressure or higher are:
When used for a single crystal silicon substrate for manufacturing a semiconductor integrated circuit device, it is selected for adjustment with the manufacturing method. The effects of the present invention can be achieved in any of the combinations.

[0017]

EXAMPLES The method of the present invention will be described below with reference to examples.

Example 1 35 kg of a polycrystalline silicon raw material was melted at a furnace pressure of 10 mbar, then the furnace pressure was increased to 100 mbar, and the P-type <
A silicon single crystal having a diameter of 100> 6 inches was pulled. The defective lot rate due to pinhole generation for 30 pulled silicon single crystals was 4.8%, the trouble occurrence rate was 0.51 times / piece, and the defect rate of carbon concentration (0.2
ppm was defined as poor) was 0.1%. These values were extremely good compared with Comparative Example 1 corresponding to the prior art described later.

Example 2 35 kg of a polycrystalline silicon raw material was melted at a furnace pressure of 10 mbar, and then the furnace pressure was increased to 1064 mbar.
A silicon single crystal of type <100> 6 inches φ was pulled up. The defective lot rate due to pinhole generation for 30 pulled silicon single crystals was 6.7%. This value was a very good value as compared with Comparative Example 3 corresponding to the prior art described later.

Example 3 35 kg of a polycrystalline silicon raw material was melted at a furnace pressure of 60 mbar, then the furnace pressure was raised to 100 mbar, and a P-type <100> 6 inch φ silicon single crystal was pulled.
The defective lot rate due to the generation of pinholes for 40 pulled silicon single crystals was 7.5%, and the trouble occurrence rate was 0.88 times / piece. This value was a very good value as compared with the prior art.

Comparative Example 1 A silicon single crystal was pulled in the same manner as in Example 1 except that the polycrystalline silicon raw material was melted at 100 mbar.
The defective lot rate due to pinhole generation for 30 pulled silicon single crystals was 10.8%, the trouble occurrence rate was 1.11 times / piece, and the carbon concentration defective rate (0.2 ppm or more was regarded as defective). ) Was 27.6%.

Comparative Example 2 35 kg of a polycrystalline silicon raw material was melted at a furnace pressure of 18 mbar, and the P-type was melted at the same furnace pressure of 18 mbar.
A silicon single crystal having a diameter of 100> 6 inches was pulled. The defective lot ratio of 30 pulled silicon single crystals caused by the generation of pinholes was as good as 1.2%, but the quartz crucible deteriorated severely and could not withstand long-term use.

Comparative Example 3 A furnace pressure of 1064 mbar was applied to 35 kg of a polycrystalline silicon raw material.
Then, while maintaining the same furnace pressure of 1064 mbar, a silicon single crystal of P type <100> 6 inch φ was pulled up. The defective lot rate due to pinhole generation for 30 pulled silicon single crystals is 15.6%
And was bad.

[0024]

As described above, according to the present invention, when pulling a silicon single crystal by the Czochralski method, the generation of pinholes in the single crystal is suppressed, the initial operation trouble is solved, and This has the effect that the carbon concentration can be reduced.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Koji Kanno, inventor, Odakura Osaikura, Nishigo-mura, Nishishirakawa-gun, Fukushima Prefecture 150 Shin-Etsu Semiconductor Co., Ltd. Shirakawa Plant (56) References Kaisho 63-268991 (JP, A)

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the polycrystalline silicon raw material is 5 to 60 mbar.
Melting the silicon single crystal at a furnace internal pressure of 100 mbar and raising the silicon single crystal at a furnace internal pressure of 100 mbar or more. 2. The method according to claim 1, wherein the polycrystalline silicon raw material is 5 to 60 mbar.
Melting the silicon single crystal at a furnace pressure of 100 to 300 mbar, and pulling the silicon single crystal at a medium furnace pressure of 100 to 300 mbar. 3. The method according to claim 1, wherein the polycrystalline silicon material is 5 to 60 mbar.
Melting the silicon single crystal at a furnace internal pressure and pulling the silicon single crystal at a normal internal pressure or higher.