JP2002154894A - Crucible for pulling semiconductor silicon, almost free from vibration at liquid surface - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quartz crucible almost free from the vibration at liquid surface and capable of being practically used. SOLUTION: The vibration at the liquid surface can be suppressed by providing a crucible for pulling a semiconductor silicon, which crucible is such one that the weight loss is <=0.013 g when 0.125 to 0.130 g of silicon is mounted on a cut sample of the crucible, then the sample and silicon are kept at 1,500 deg.C in gaseous Ar for 30 min under normal pressure and the formed SiO2 vapor is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a quartz glass crucible for pulling single crystal silicon. Particularly, the present invention relates to a quartz glass crucible which is most suitable for pulling a large-diameter silicon ingot.

[0002]

2. Description of the Related Art CZ which is a method of manufacturing a silicon single crystal
In the (Czochralski) method, polysilicon is put into quartz glass, melted with a seed crystal after melting, and a single crystal is pulled up. In recent years, however, the amount of polysilicon charged has been increased and pulled up at a time to reduce costs. Have many. As a quartz glass crucible resistant to this method, a crucible having a layer of synthetic quartz glass on its inner surface, which is hardly devitrified, is used.

[0003]

However, when this synthetic quartz crucible is used, a phenomenon occurs in which the liquid surface of silicon vibrates, and in a severe case, there occurs a problem that the seed crystal does not adhere to the liquid surface. This solution level is urgently needed because the liquid level vibration significantly lowers the overall yield.

[0004]

The inventors of the present invention have found that the cause of the liquid level vibration is a reaction between a quartz crucible and silicon.
We have determined that this is due to SiO gas, established an evaluation method, and invented a crucible that reduces liquid level vibration until practically no problem occurs.

[0005]

According to the present invention, 0.125 g to 0.130 g of silicon is placed on a cut crucible sample, and Ar
Provided is a quartz glass crucible characterized by having low liquid level vibration when kept in a gas at 1500 ° C. and normal pressure for 30 minutes, and the weight loss after removing generated SiO 2 vapor is 0.013 g or less. The present inventors have measured the amount of dissolved oxygen by the drop method in cooperation with Prof. Hirakawa of Shinshu University. According to this method, the amount of quartz glass dissolved can be easily obtained. The present inventors separately struggled with the problem due to liquid level vibration of the synthetic crucible. While analyzing the cause, we focused on the gas generated from the interface between the quartz crucible and the silicon melt. The present inventors have linked the two, and have invented a crucible with less liquid surface vibration evaluation and liquid surface vibration. To raise the silicon ingot, add polysilicon to the quartz crucible and raise the temperature from 1500 ° C to 1600 ° C to dissolve it. Recently, there is a tendency to increase the temperature in order to shorten the dissolution time. At this time, quartz glass and silicon are reacting as follows. SiO2 + Si → 2SiO (gas)
Since SiO is a gas, it evaporates from the upper part of silicon, and the amount of gas at this time affects the liquid surface vibration. The difference in the gas amount due to the quartz crucible can be easily known by the drop method. First, put 0.125 g of silicon on the cut crucible sample
0.130g, put in Ar gas, 1500 ℃, hold at normal pressure for 30 minutes,
The weight loss after removing the generated SiO2 vapor is measured. This value is much larger than the actual quartz crucible at the time of pulling up silicon. This is because the contact area is smaller than the evaporation area. However, when this value was obtained for a crucible having a liquid level vibration and a crucible not having the liquid level vibration, it was found that when the weight was reduced to 0.013 g or less, the liquid level vibration did not occur.

[0006]

EXAMPLES Examples of the present invention and comparative examples are shown below. Example 1 A 22 "synthetic quartz crucible was crucible 8 having a different OH content by a conventional method.
Individual pieces were produced. This was cut into 6 mm x 6 mm, washed with HF, dried and weighed. This sample was placed on a quartz plate, and 0.13 g of polysilicon was placed thereon. The inside of this furnace was replaced with argon, the temperature was raised to 1500 ° C. in 2 hours, and after maintaining for 30 minutes, the power was turned off and the product was naturally cooled. The sample was taken out, the attached SiO2 was removed with an ultrasonic cleaner, dried, and weighed. The results are shown in Table 1. Also put 120kg of polysilicon into this crucible, dissolve after holding at 20torr,
The presence or absence of liquid level vibration was examined. The results are also shown in Table 1. table 1

[0007]

According to the present invention, there is provided a quartz crucible which can be practically used with little liquid surface vibration.

Claims (1)

[Claims] 1. Place 0.125 g to 0.130 g of silicon on a cut crucible sample, and in Ar gas at 1500 ° C. and normal pressure.
A crucible for pulling up semiconductor silicon with low liquid surface vibration, characterized in that the weight loss after removing the generated SiO2 vapor for 30 minutes is 0.013g or less.