JPH0367994B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for pulling and growing silicon (Si) single crystal ingots with significantly fewer defects. [Prior Art] Generally, a Si single crystal ingot is held in a quartz crucible 3 supported by a rotating shaft 2 at the lower part of a pulling device 1, and is kept in a heat-insulating state. A seed crystal 8 attached to the tip of a pulling shaft 7 is immersed in Si melt 6 heated by a heater 5 provided between the body 4 and the crucible 3, and while rotating the pulling shaft 7, It is manufactured by growing a Si single crystal ingot 9 by pulling at a speed of 1/min. Therefore, if the length of a Si single crystal ingot immediately after pulling and growing is, for example, 30 cm, the temperature distribution will drop from about 1400°C at the bottom end to about 800°C at the top end, and the pulling speed will be If the speed is approximately 1 mm/min, the manufacturing time will be approximately 300 minutes (approximately 5 hours). [Problems to be solved by the invention] However, since the Si single crystal ingot that has been pulled and grown contains supersaturated impurity oxygen, there are many nuclei that form the source of oxygen precipitates. Therefore, in the semiconductor device process, the
When wafers manufactured from Si single crystal ingots are subjected to various high-temperature treatments, oxygen precipitates are formed on the wafers around the cores, and the formation of these oxygen precipitates is caused by dislocations. This causes defects such as stacking faults and stacking faults, and these defects lead to serious property deterioration such as poor insulation of semiconductor devices and shortened carrier lifetime. [Means for Solving the Problems] Therefore, from the above-mentioned viewpoint, the present inventors have developed a method for obtaining wafers with fewer defects in the semiconductor device process, especially regarding Si single crystal ingots that are the raw material for the wafers. As a result of research, we found that from the Si melt held in the crucible in the pulling device,
When pulling and growing a Si single-crystal ingot, the Si single-crystal ingot being pulled and grown is exposed to temperatures ranging from 1100℃ to 900℃ within the temperature drop distribution.
℃ (hereinafter referred to as the controlled lowering temperature range) over a period of 3 hours or more (by the way, in the conventional pulling growth method,
(It takes about 2 hours to lower the temperature from 1100℃ to 900℃), the number of nuclei that cause oxygen precipitates in the subsequent process in Si single crystal ingots is reduced, and as a result, Si single crystal ingots are reduced. Even when the crystal wafer is exposed to various high-temperature treatments in the semiconductor device process, the presence of the nuclei is suppressed, so the generation of oxygen precipitates formed based on the nuclei is reduced.
Therefore, it has been found that the occurrence of defects is significantly reduced. This invention was made based on the above-mentioned findings, and the reason for setting the controlled decreasing temperature range to 1100 to 900°C and setting the holding time in this controlled decreasing temperature range to 3 hours or more was based on empirical results based on various experimental results. Therefore, from 1100℃ to 900℃
℃ in less than 3 hours, or even if the holding time is 3 hours or more, even if the controlled temperature drop range deviates to the higher or lower side, oxygen precipitation may occur in the Si single crystal ingot. Therefore, it is not possible to sufficiently reduce the number of nuclei that cause defects, and the effect of suppressing the occurrence of defects in the semiconductor device process cannot be obtained. [Example] Next, the method of the present invention will be specifically explained with reference to Examples. Using the Si single crystal manufacturing equipment shown in Figure 1,
When pulling and growing a Si single crystal ingot with diameter: 130 mmφ x length: 500 mm at a pulling speed of 1 mm/min, the Si single crystal being pulled and grown as shown in the same schematic diagram in Figure 2. Temperature of ingot 9: zone above the 1200℃ position,
That is, a multi-stage variable heater 10 is provided as a temperature control device at a location where the lower end is located 100 mm above the upper end of the quartz crucible 3, and with respect to the Si single crystal ingot 9 being pulled and grown by the multi-stage variable heater 10, Temperature control was performed under the conditions shown in Table 1 (as a result, the Si single crystal ingot 9 was uniformly subjected to predetermined temperature control over its entire length), and the Si single crystal ingot 9 After the lower end of the is subjected to said temperature control,
By pulling this up and cooling it, methods 1 to 3 of the present invention
and Comparative Methods 1 to 3 were carried out, respectively. If no temperature control treatment is applied to the Si single crystal ingot that is being pulled and grown, the temperature of the Si single crystal ingot immediately after the end of pulling and growing will be approximately 1400°C along its length; :about
The temperature distribution was 900°C, and the upper end: approximately 600°C. Next, samples were taken from the upper end, center, and lower end of the Si single crystal ingots obtained by methods 1 to 3 of the present invention and comparative methods 1 to 3, and subjected to various high-temperature treatments in the semiconductor device process. Assuming that

〔Effect of the invention〕

From the results shown in Table 1, in the Si single crystal ingots produced by methods 1 to 3 of the present invention, the number of nuclei, which are the source of oxygen precipitates during the semiconductor device process, is significantly reduced. As a result, the generation of oxygen precipitates in the semiconductor device process has been significantly suppressed.
While this reduces the occurrence of defects, as seen in Comparative Methods 1 to 3, when the temperature control conditions deviate from the scope of the present invention, oxygen precipitates may occur. Nucleus reduction becomes insufficient,
It is clear that the generation of oxygen precipitates during high-temperature treatment cannot be suppressed, and that the generation of defects in Si single crystal wafers cannot be sufficiently suppressed. As described above, according to the method of the present invention, it is possible to produce a Si single crystal ingot with extremely few nuclei, which are the source of oxygen precipitates in the semiconductor device process. Si single-crystal wafers manufactured from Si single-crystal ingots have industrially useful effects such as extremely low occurrence of defects.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a conventional pulling growth method for a Si single crystal ingot, and FIG. 2 is a schematic diagram showing an embodiment of the pulling growth method of the present invention. 1... Pulling device, 2... Rotating shaft, 3... Quartz crucible, 4... Heat insulator, 5... Heater, 6... Si
Melt, 7... Pulling axis, 8... Seed crystal, 9... Si
Crystal ingot, 10...Multi-stage variable heater.

Claims (1)

[Scope of Claims] 1. In a method of pulling and growing a silicon single crystal ingot from a silicon melt held in a crucible in a pulling device, the silicon single crystal ingot being pulled and grown is given a drop in its temperature distribution. From 1100℃
Silicon with low defect generation, which is characterized by reducing the number of nuclei that cause oxygen precipitates in the semiconductor device process by controlling the temperature by gradually lowering the temperature to 900°C over three hours or more. A method for pulling and growing single crystal ingots.