JP2612033C - - Google Patents

Description

The present invention relates to a method for growing a silicon single crystal by a CZ method, and more particularly to an improvement capable of effectively suppressing the occurrence of stacking faults. [Prior Art] In a silicon single crystal manufactured by the CZ method, stacking faults occur when various high-temperature treatments are performed in a semiconductor device process, and these stacking faults cause a breakdown voltage failure of a semiconductor device or a carrier. It is known to cause a reduction in the lifetime of the product. Conventionally, it is thought that the main cause of the above stacking faults is oxygen dissolved in single crystals in supersaturation. That is, when the CZ single crystal is subjected to a high-temperature treatment, fine oxygen precipitates such as SiO ₂ are generated from the dissolved oxygen and coarsened, and the interstitial silicon released from the oxygen precipitates causes secondary defects. Stacking faults occur. The present applicants have previously proposed in Japanese Patent Application Laid-Open No. 61-201692 a method for growing a silicon single crystal capable of suppressing generation of oxygen precipitates. In this method, a temperature controller is provided in a predetermined zone of the silicon single crystal being pulled,
The silicon single crystal is maintained at a temperature range of 1100 to 900 ° C. for 3 hours or more over its entire length, thereby suppressing the generation of oxygen precipitates, and consequently, stacking faults during high temperature processing in a semiconductor device process. It was to reduce the occurrence. "Problems to be Solved by the Invention" However, according to subsequent studies by the present inventors, although the growth method certainly suppresses the generation of oxygen precipitates, the stacking fault density after high-temperature treatment is rather increased. Was confirmed. Therefore, the present inventors again conducted a detailed study of the stacking fault generation mechanism, and found that the stacking faults generated in this case were not formed by interstitial silicon released by the coarsening of the oxygen precipitate. Was. Therefore, the present inventors newly tried single crystal growth under various temperature conditions, and set the residence time required for the silicon single crystal to pass through the temperature range of 850 to 1050 ° C. by one.
It was found that when the time was set to 40 minutes or less, the stacking fault density in the single crystal could be reduced. "Means for Solving the Problems" The present invention has been made based on the above-mentioned knowledge, and by means of, for example, providing a temperature control mechanism in a predetermined zone of a silicon single crystal to be pulled, the 850-1
The residence time in the temperature range of 050 ° C. is 140 minutes or less. In addition, when the residence time at 850 to 1050 ° C. exceeds 140 minutes, or when the temperature range shifts up and down even when the residence time is 140 minutes or less, any of the stacking faults generated during the high-temperature treatment is reduced. The density increases, and the conventional problems cannot be solved. "Examples" Next, the effects of the present invention will be demonstrated with examples. The figure shows a silicon single crystal growing apparatus used in the experiment.
Is a rotary shaft, 3 is a quartz crucible for holding the molten silicon Y, 4 is a heater, 5 is a heat retaining cylinder, 6 is a pulling shaft, and 7 is a seed crystal. Numeral 8 is a cooling mechanism that appropriately cools a predetermined zone of the single crystal T being pulled up and controls the cooling rate. Using the above apparatus, at a lifting speed of 1 mm / min, 155 mmφ × 600 m
An m-length silicon single crystal was manufactured. As the cooling mechanism 8, a ring-shaped metal reflector, a water-cooled jacket, or the like was selected and used depending on the temperature. And 600-8
The residence time of the single crystal in each temperature range of 50 ° C., 850 to 1050 ° C., and 1050 to 1400 ° C. was adjusted so as to be uniform over the entire length. Next, wafers were cut out from the eight single crystals thus obtained, and these wafers were heated to 1100 ° C. at a rate of 2 ° C./min, held for 1 hour, and then subjected to a high-temperature treatment of cooling, and the stacking fault density generated on the wafers Was measured. The following table shows the results. As is clear from the results in the above table, in the single crystals manufactured according to Examples 1 and 2,
While the generation of stacking faults on the wafer is extremely small,
In the cases where the residence time in the range is longer than 140 minutes or the temperature range in which the residence time is 140 minutes or less is shifted up and down, stacking faults occur at a high density. [Effects of the Invention] As described above, according to the method for growing a silicon single crystal of the present invention, a high-quality silicon single crystal with few stacking faults is produced even when high-temperature processing is performed in a semiconductor device process. It is possible.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view showing a silicon single crystal growing apparatus used in an embodiment of the present invention. 3 Quartz crucible, 4 Heater, 6 Pull-up shaft, 7 Seed crystal, 8 Cooling mechanism,
T: silicon single crystal.

Claims (1)

Claims: In a method for growing a silicon single crystal in which a seed crystal is immersed in a molten silicon and a single crystal is pulled up, the method comprises the steps of:
A method for growing a silicon single crystal, characterized in that the residence time in only the temperature range of 850 to 1050 ° C out of the respective temperature ranges of 050 to 1400 ° C is 140 minutes or less.