CN-121976284-A - Crystal pulling method of monocrystalline silicon and silicon wafer

CN121976284ACN 121976284 ACN121976284 ACN 121976284ACN-121976284-A

Abstract

The embodiment of the application relates to the field of photovoltaics, and provides a crystal pulling method of monocrystalline silicon and a silicon wafer, wherein the method comprises the steps of vacuumizing a monocrystalline furnace; the method comprises the steps of heating silicon materials in a crucible to a molten state, controlling the flow of inert gas in a single crystal furnace in a re-feeding stage to be the same as the flow of inert gas in a heating process, controlling the working frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the working frequency of the mechanical pump in the heating process, and controlling technological parameters including the rotation speed of the crucible, the furnace pressure of the single crystal furnace and the rotation speed of the single crystal silicon to be unchanged in the process of increasing the equal-diameter length of the single crystal silicon from 0 to a preset length in the equal-diameter stage. The solar cell provided by the embodiment of the application is at least beneficial to solving the problem of low survival rate of first-time casting in the monocrystalline silicon production process in the prior art.

Inventors

OU ZIYANG
LI XIAOLONG
MA JIANQIANG
Chen Zhancang

Assignees

青海晶科能源有限公司

Dates

Publication Date: 20260505
Application Date: 20260204

Claims (10)

1. A method of pulling monocrystalline silicon, comprising: Vacuumizing the single crystal furnace; placing a silicon material into a crucible, and heating the silicon material in the crucible to a molten state; controlling the flow rate of inert gas in the single crystal furnace in a re-feeding stage to be the same as the flow rate of the inert gas in a heating process, and controlling the working frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the working frequency of the mechanical pump in the heating process, wherein the heating process is a process of heating the silicon material to the molten state, and the re-feeding stage is a stage of continuously adding the silicon material into the crucible again after heating the silicon material to the molten state; In the process of increasing the isodiametric length of the monocrystalline silicon from 0 to a preset length in the isodiametric stage, controlling technological parameters to be unchanged, wherein the technological parameters comprise the rotation speed of the crucible, the furnace pressure of the monocrystalline furnace and the rotation speed of the monocrystalline silicon.
2. The method for pulling a silicon single crystal according to claim 1, wherein the predetermined length is 400mm to 600mm.
3. A method for pulling a silicon single crystal as defined in claim 1, wherein, The vacuum-pumping treatment is carried out in the single crystal furnace, which comprises the vacuum-pumping treatment is carried out on the single crystal furnace for 3min-5min, Heating the silicon material in the crucible to a molten state comprises heating the silicon material to the molten state under the conditions that the flow rate of the inert gas is 150slpm-250slpm, the furnace pressure is 12torr-18torr and the working frequency of the mechanical pump is 30% -40% of the maximum frequency of the mechanical pump.
4. The method for pulling silicon single crystal according to claim 1, wherein after the vacuum treatment of the single crystal furnace, before placing the silicon feedstock into a crucible and heating the silicon feedstock in the crucible to a molten state, the method further comprises: And performing leak detection operation on the single crystal furnace, and determining that the single crystal furnace does not meet the leak detection standard under the condition that the leak rate of the vacuum system in the single crystal furnace is detected to be larger than the maximum leak rate.
5. The method for pulling a silicon single crystal according to claim 1, wherein after controlling the operating frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the operating frequency of the mechanical pump in the heating process, the method further comprises, before controlling the process parameters to remain unchanged during the course of increasing the isodiametric length of the silicon single crystal from 0 to a preset length in the isodiametric stage: In the temperature control stage, under the condition that the temperature of the surface of the silicon melt in the crucible reaches a preset temperature, controlling the power of a main heater in the single crystal furnace to be 75-85 kw, wherein the preset temperature is 55-60 ℃, the silicon melt is the silicon material in the molten state, and the temperature control stage is a stage of controlling the temperature of the silicon melt within a preset temperature range; In the temperature adjustment stage, the position of the preheated seed crystal is controlled to be larger than a preset distance, the position of the preheated seed crystal is the distance between the seed crystal and the surface of the silicon melt, the preset distance is 400-600 mm, and the temperature adjustment stage is a stage of finely adjusting the temperature of the silicon melt according to the growth process of the monocrystalline silicon on the basis of temperature control.
6. The method for pulling a silicon single crystal according to claim 1, wherein after controlling the operating frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the operating frequency of the mechanical pump in the heating process, the method further comprises, before controlling the process parameters to remain unchanged during the course of increasing the isodiametric length of the silicon single crystal from 0 to a preset length in the isodiametric stage: in the seeding stage, the seeding length is controlled to be 250mm-270mm.
7. The method for pulling a silicon single crystal according to claim 1, wherein after controlling the operating frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the operating frequency of the mechanical pump in the heating process, the method further comprises, before controlling the process parameters to remain unchanged during the course of increasing the isodiametric length of the silicon single crystal from 0 to a preset length in the isodiametric stage: In the shouldering stage, the shouldering length is controlled to be 200-270 mm, the shouldering pulling speed is controlled to be 70-80 mm/h, the liquid opening distance is controlled to be 35-40 mm, the liquid opening distance is the distance between the surface of silicon melt in the crucible and the top of the crucible, and the silicon melt is the silicon material in the molten state.
8. The method for pulling a silicon single crystal according to claim 1, wherein after controlling the operating frequency of a mechanical pump in the single crystal furnace in the re-feeding stage to be the same as the operating frequency of the mechanical pump in the heating process, the method further comprises, before controlling the process parameters to remain unchanged during the course of increasing the isodiametric length of the silicon single crystal from 0 to a preset length in the isodiametric stage: in the shoulder rotating stage, the shoulder rotating pulling speed is controlled to be 140mm/h-150mm/h.
9. The method of pulling a silicon single crystal of claim 1, wherein the single crystal furnace further comprises a thermal field, the thermal field comprising a thermal field bottom portion and a thermal field top portion, the thermal field bottom portion comprising a bottom soft felt, a bottom solid felt, a lower insulating bucket, a bottom guard wafer, and an electrode, the thermal field top portion comprising an upper insulating bucket, a thermal shield, a heater, a top soft felt, and a top solid felt, the method further comprising, prior to evacuating air within the single crystal furnace: and removing the top part of the thermal field, reserving the bottom part of the thermal field, and cleaning gaps and surfaces in the bottom part of the thermal field.
10. A silicon wafer, characterized in that it is produced by the method for pulling up a single crystal silicon according to any one of claims 1 to 9.

Description

Crystal pulling method of monocrystalline silicon and silicon wafer Technical Field The application relates to the field of photovoltaics, in particular to a crystal pulling method of monocrystalline silicon and a silicon wafer. Background The single crystal industry is vigorously developed, the manufacturing scale of the solar single crystal is larger and larger, meanwhile, the requirement on the yield of the single crystal is higher and higher, under the condition of extremely strong competition, the technological requirements of each procedure in the production process are strictly controlled, the single yield requirement is higher and higher, the first throwing line breaking rate is high under the current large environment for improving the single yield, the influence on the whole furnace yield is great, and the first throwing survival rate is lower. Disclosure of Invention The embodiment of the application provides a crystal pulling method of monocrystalline silicon and a silicon wafer, which are at least beneficial to improving the problem of low survival rate of first-time casting in the production process of the monocrystalline silicon in the prior art. According to some embodiments of the present application, an aspect of the present application provides a method for pulling a silicon single crystal, including performing a vacuum process on a silicon single crystal furnace, placing a silicon material into a crucible, and heating the silicon material in the crucible to a molten state, controlling a flow rate of an inert gas in the silicon single crystal furnace in a re-feeding stage to be the same as a flow rate of the inert gas in a heating process, and controlling an operating frequency of a mechanical pump in the silicon single crystal furnace in the re-feeding stage to be the same as an operating frequency of the mechanical pump in the heating process, wherein the heating process is a process of heating the silicon material to the molten state, and the re-feeding stage is a stage of continuing to add the silicon material into the crucible again after the silicon single crystal material is heated to the molten state, wherein a process parameter is controlled to remain unchanged during an increase of an equal diameter length of the silicon single crystal from 0 to a preset length in an equal diameter stage, and the process parameter includes a rotation speed of the crucible, a furnace pressure of the silicon single crystal furnace, and a rotation speed of the silicon single crystal. In some embodiments, the predetermined length is 400mm-600mm. In some embodiments, the vacuum-pumping treatment is performed in the single crystal furnace, wherein the vacuum-pumping treatment is performed on the single crystal furnace for 3-5 min, and the silicon material in the crucible is heated to a molten state, and the silicon material is heated to the molten state under the conditions that the flow rate of the inert gas is 150slpm-250slpm, the furnace pressure is 12-18 torr, and the working frequency of the mechanical pump is 30-40% of the maximum frequency of the mechanical pump. In some embodiments, after the single crystal furnace is vacuumized, before placing silicon material into a crucible and heating the silicon material in the crucible to a molten state, the method further comprises performing leak detection operation on the single crystal furnace, and determining that the single crystal furnace does not meet leak detection standards if the leak rate of a vacuum system in the single crystal furnace is detected to be greater than a maximum leak rate. In some embodiments, after the operating frequency of the mechanical pump in the single crystal furnace is controlled to be the same as the operating frequency of the mechanical pump in the heating process in the re-feeding stage, before the process parameters are controlled to be unchanged in the process of increasing the equal diameter length of the single crystal silicon from 0 to a preset length in the equal diameter stage, the method further comprises a temperature control stage, in which the power of a main heater in the single crystal furnace is controlled to be 75kw-85kw under the condition that the temperature of the surface of the silicon melt in the crucible reaches a preset temperature, the preset temperature is 55 ℃ to 60 ℃, the silicon melt is the silicon material in the molten state, the temperature control stage is a stage of controlling the temperature of the silicon melt within a preset temperature range, the preheating seed crystal position is controlled to be larger than the preset distance, the preheating seed crystal position is the distance between the seed crystal and the surface of the silicon melt, the preset distance is 400mm-600mm, and the temperature control stage is a stage of finely adjusting the temperature of the silicon melt according to the growth progress of the silicon melt on the basis of the temperature control. In some