CN115341268A - A Method for Automatically Controlling the Resistivity of Monocrystalline Silicon - Google Patents

Abstract

The invention provides a method for automatically controlling the resistivity of single crystal silicon. Gas doping is carried out in the process of Czochralski single crystal, including: setting the gas doping opening node and gas flow rate; performing single crystal pulling; During the manufacturing process, the contact voltage of the melt in the crucible is obtained, and the single crystal resistivity is automatically calculated according to the contact voltage; the single crystal pulling process is judged, and if the set gas doping opening node condition is met, the gas is controlled to enter the single crystal furnace Doping is performed within the single crystal; at the same time, the flow rate of the gas is controlled according to the calculated resistivity of the single crystal to control the axial resistivity of the single crystal; otherwise, the pulling of the single crystal is continued. The beneficial effect of the present invention is to add an automatic aeration system, set the conditions for the doping gas to start doping, the control system controls the action of the automatic aeration system, and feed the doping gas, according to the contact voltage of the single crystal and the melt of different weights in the crucible Obtain the resistivity of the single crystal, automatically control the change of the flow rate of the doping gas, and control the axial attenuation of the resistivity of the single crystal.

Description

A Method for Automatically Controlling the Resistivity of Monocrystalline Silicon

technical field

The invention belongs to the technical field of photovoltaics, in particular to a method for automatically controlling the resistivity of single crystal silicon.

Background technique

In the prior art, gallium-doped single crystal has the advantage of low light attenuation compared with boron-doped single crystal, which promotes the market demand for gallium-doped single crystal. However, due to the extremely small segregation coefficient of Ga (Ga: 0.008, B: 0.8 ), the resistivity distribution is wider when the same rod length is drawn. At present, solid-phase doping is generally used in the industry for doping. This doping method cannot meet the requirements of single crystal quality during the crystal pulling process, and cannot achieve automatic and continuous compensation.

Contents of the invention

In view of the above problems, the present invention provides a method for automatically controlling the resistivity of single crystal silicon to solve at least one of the above or other former problems existing in the prior art.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a method for automatically controlling the resistivity of single crystal silicon, and gas doping is carried out in the process of Czochralski single crystal, including:

Set gas doping open node and gas flow rate;

Perform single crystal pulling;

During the single crystal pulling process, the contact voltage of the melt in the crucible is obtained, and the single crystal resistivity is automatically calculated according to the contact voltage;

Judging the single crystal pulling process, if the set gas doping start node condition is met, the control gas is input into the single crystal furnace for doping; at the same time, the flow rate of the gas is controlled according to the calculated single crystal resistivity, and the single crystal axis is controlled. resistivity;

Otherwise, no gas is input into the single crystal furnace.

Further, the gas doping turns on the node for the single crystal pulling to enter the shoulder expansion stage or the equal diameter stage.

Further, the gas flow rate is 0-1L/min.

Further, the gas is a mixed gas of phosphine and argon.

Further, controlling the flow change of the gas according to the calculated single crystal resistivity includes:

As the resistivity of the single crystal decreases, the flow rate of the gas gradually increases. When the resistivity of the single crystal decreases by one change in resistivity, the flow rate of the gas increases by one change in flow rate to control the attenuation of the axial resistivity of the single crystal.

Further, the resistivity variation is 0-1Ω·cm/m, and the gas flow variation is 0-1L/min.

Further, the gas is mixed with the argon gas and the first gas according to a certain flow ratio.

Further, the flow ratio of the argon gas to the first gas is 2:1-10:1.

Further, the first gas is a mixed gas of argon and phosphine.

Due to the adoption of the above-mentioned technical scheme, in the crystal pulling process of Czochralski single crystal, the conditions for the doping gas to start doping are set. When the set conditions are met, the control system controls the action of the automatic ventilation system, and the doping gas is introduced into the single crystal furnace; the resistance of the single crystal in different periods is calculated according to the contact voltage between the single crystal and the melt of different weights in the crucible Rate, and according to the change of the resistivity of the single crystal, automatically control the change of the flow rate of the dopant gas, thereby controlling the axial attenuation of the resistivity of the single crystal, so that the attenuation of the axial resistivity of the single crystal is slow; the axis of the single crystal The axial resistivity can be automatically controlled, the head resistivity can be automatically measured, and the axial attenuation of the single crystal resistivity can be automatically controlled according to the head resistivity; the single crystal resistivity can be controlled according to the axial attenuation law of the single crystal resistivity, which can realize The distribution range of single crystal resistivity can be customized according to requirements.

Description of drawings

Fig. 1 is a schematic structural diagram of an automatic ventilation system according to an embodiment of the present invention.

In the picture:

1. The first flow detection device 2. The first switch 3. The second switch

4. Second flow detection device 5. Pressure regulating device 6. Proportioning device

7. Single crystal furnace

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

An embodiment of the present invention relates to a method for automatically controlling the resistivity of single crystal silicon, which is used for gas-phase doping of phosphorus element during the pulling process of gallium-doped single crystal, to suppress the attenuation of single crystal resistivity, and to control the single crystal axis. The axial resistivity of the single crystal can be controlled automatically. During the process of pulling the single crystal, the resistivity of the head is automatically measured, and the flow rate of the doping gas is controlled according to the resistivity of the head to automatically control the resistivity. The axial attenuation, and the automatic ventilation system is easy to develop, and the input cost is low, so that the axial distribution range of single crystal resistivity can be customized. There is no need for manual intervention in the crystal pulling process, and automatic control can be realized throughout the process, with a high degree of automation.

A method for automatically controlling the resistivity of single crystal silicon, gas doping is carried out in the process of Czochralski single crystal, especially refers to the doping of phosphorus element in the process of pulling gallium-doped single crystal to control the segregation of gallium element Speed, controlling the attenuation of the axial resistivity of the single crystal, controlling the distribution range of the axial resistivity of the single crystal, specifically, the method for automatically controlling the resistivity of the single crystal silicon includes:

Set the gas doping start node and gas flow rate: in the single crystal pulling control system, preset the single crystal pulling process, perform single crystal pulling according to the pulling process, and set in the single crystal pulling process The doping gas doping starts the node, controls the start timing of the doping gas doping in the crystal pulling process, and controls the gas flow rate when the doping gas starts doping, and starts the doping gas doping; wherein, the gas doping The opening node is the seeding stage, the shoulder expansion stage or the equal-diameter stage of single crystal pulling, which can be selected according to actual needs, and no specific requirements are made here; the gas flow rate is 0-1L/min, and the gas flow rate can be 0.1L/min , 0.3L/min, 0.5L/min, 0.7L/min, 0.9L/min or 1L/min, choose according to actual needs, no specific requirements here.

Perform single crystal pulling: perform single crystal pulling according to the crystal pulling process preset by the control system. At the same time, the doping start node and gas flow rate of the doping gas are preset in the crystal pulling process, and the conditions are judged during the crystal pulling process , whether doping with doping gas is performed;

During the single crystal pulling process, the contact voltage of the melt in the crucible is obtained, and the single crystal resistivity is automatically calculated according to the contact voltage: during the single crystal pulling process, the weight of the melt in the crucible decreases continuously, and the single crystal and the Different weights of melts will have different voltage changes when they are in contact. The control system measures different voltages, and calculates the resistivity of single crystals in different periods according to the measured voltages. The resistivity of single crystal, so that the resistivity of single crystal can be detected from time to time;

Judging the single crystal pulling process, if the set gas doping start node condition is met, the control gas is input into the single crystal furnace for doping, and at the same time, the flow rate of the gas is controlled according to the calculated single crystal resistivity, and the single crystal axis is controlled. to resistivity. The flow rate changes of the control gas based on the calculated single crystal resistivity include:

As the resistivity of the single crystal decreases, the flow rate of the gas gradually increases, the resistivity of the single crystal decreases by a resistivity change, and the gas flow increases by a flow change, so as to control the attenuation of the axial resistivity of the single crystal, the resistivity change The amount is 0-1Ω·cm/m, and the resistivity change amount can be 0.05Ω·cm/m, 0.1Ω·cm/m, 0.15Ω·cm/m, 0.2Ω·cm/m, 0.25Ω·cm/ m, 0.3Ω·cm/m, 0.35Ω·cm/m, 0.4Ω·cm/m, 0.45Ω·cm/m, 0.5Ω·cm/m, 0.55Ω·cm/m, 0.6Ω·cm/m , 0.65Ω·cm/m, 0.7Ω·cm/m, 0.75Ω·cm/m, 0.8Ω·cm/m, 0.85Ω·cm/m, 0.9Ω·cm/m, 0.95Ω·cm/m or 1Ω·cm/m, choose according to actual needs, no specific requirements are made here; the flow rate change of the gas is 0-1L/min, and the flow rate change of the gas can be 0.01L/min, 0.02L/min, 0.03L /min, 0.04L/min, 0.06L/min, 0.08L/min, 0.1L/min, 0.15L/min, 0.2L/min, 0.25L/min, 0.3L/min, 0.35L/min, 0.4L /min, 0.45L/min, 0.5L/min, 0.55L/min, 0.6L/min, 0.65L/min, 0.7L/min, 0.75L/min, 0.8L/min, 0.85L/min, 0.9L /min, 0.95L/min or 1L/min, choose according to actual needs, no specific requirements here.

The above gas is a mixed gas of phosphine and argon, the gas concentration is 1000-10000ppm, the gas concentration can be 1000ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, 6000ppm, 7000ppm, 8000ppm, 9000ppm or 10000ppm, according to actual needs Make a selection, no specific requirements are made here.

In order to realize the above-mentioned gas-phase doping of phosphorus element automatically in the Czochralski single crystal process, an automatic aeration system is added in the Czochralski single crystal system, so that the mixed gas containing phosphorus can flow as expected under the action of the automatic aeration system. The set program operates to control the timing and time of the introduction of the mixed gas containing phosphorus element, and performs automatic gas phase doping on the Czochralski single crystal.

Specifically, an automatic ventilation system, as shown in Figure 1, includes a first gas path, a second gas path and a proportioning device 6, the first gas path and the second gas path communicate with the proportioning device 6 respectively, the first The gas circuit is used to control the introduction of argon gas, and the second gas circuit is used to introduce the first gas; wherein, one end of the first gas circuit is connected to the proportioning device 6, and the other end of the first gas circuit is connected to the argon storage The device is connected so that the argon gas storage device flows out from the argon gas storage device under the action of the first gas path and enters the proportioning device 6. One end of the second gas path is connected to the proportioning device 6, and the other end of the second gas path One end is connected to the storage device of the first gas, so that the first gas flows out from the storage device of the first gas under the action of the second gas path, and enters the proportioning device 6; the connection between the first gas path and the second gas path The arrangement can realize the directional flow of the argon gas and the first gas, and can realize continuous input of the argon gas and the first gas into the single crystal furnace 7, and input the dopant gas while inputting the protective gas during the crystal pulling process. The crystal is vapor phase doped.

The proportioning device 6 is used for proportioning the flow rate of the argon gas and the flow rate of the first gas, and the gas outlet of the proportioning device 6 is communicated with the single crystal furnace 7, and the gas after the proportioning is passed into the single crystal furnace 7, from The argon gas flowing out of the first gas path and the first gas flowing out of the second gas path are proportioned and mixed in the proportioning device 6, and the mixed gas is input into the single crystal furnace 7 for doping gas and protection Continuous input of gas. Here, the mixed gas formed by mixing the argon gas and the first gas through the proportioning device 6 is the dopant gas. When the proportioning device 6 mixes and proportions the argon gas with the first gas, the ratio of the flow rate of the argon gas to the flow rate of the first gas is 2:1-10:1, and the ratio of the flow rate of the argon gas to the flow rate of the first gas The ratio can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1 or 10:1, choose according to actual needs, no specific requirements here .

Specifically, the above-mentioned first gas circuit includes a first pipeline, a first switch 2 and a first flow detection device 1, and the first switch 2 and the first flow detection device 1 are arranged on the first pipeline to control the flow rate of the first gas circuit. The opening, closing and gas flow rate of the first pipeline are convenient to guide the flow of argon, so that the argon flows along the direction of the first pipeline and enters the proportioning device 6. The first pipeline It is a connecting pipeline, and it is a connecting pipeline resistant to low temperature and high pressure, which can transport argon gas; the setting of the first switch 2 is used to control the opening and closing of the first gas circuit. When the first switch 2 is opened, the argon The gas can flow out from the argon storage device along the first pipeline and flow into the proportioning device 6. When the first switch 2 is closed, the argon gas can flow out from the argon storage device, and the argon cannot flow along the first The pipeline flows into the proportioning device 6, and the first pipeline is in a closed state. The first switch 2 can be a shut-off valve, or a solenoid valve, or other valves capable of opening and closing the pipeline. It is selected according to the needs, and no specific requirements are made here. Preferably, in this embodiment, the first switch 2 is a solenoid valve, which is a commercially available product. It is selected according to actual needs, and no specific requirements are made here.

The above-mentioned first flow detection device 1 is used to detect the flow of argon in the first pipeline, and the first flow detection device 1 is a flow meter. Preferably, in this embodiment, the first flow detection device 1 is a mass The flowmeter is a commercially available product, and it is selected according to actual needs, and no specific requirements are made here.

In this embodiment, preferably, the first switch 2 and the first flow detection device 1 are arranged in sequence along the flow direction of the argon gas.

The above-mentioned second gas circuit includes a second pipeline, a pressure regulating device 5, a second switch 3 and a second flow detection device 4, and the pressure regulating device 5, the second switch 3 and the second flow detection device 4 are all arranged on the second On the pipeline, control the pressure, flow rate and opening and closing of the second gas circuit. The setting of the second pipeline enables the first gas to flow out from the storage device of the first gas, flow along the direction of the second pipeline, and flow into the In the proportioning device 6, the flow of the first gas is guided, and the second pipeline is a connecting pipeline, which is resistant to low temperature and high pressure, and is selected according to actual needs, and no specific requirements are made here.

The setting of the above-mentioned second switch 3 is used to control the opening and closing of the second gas path. When the second switch 3 is turned on, the first gas can flow out from the first gas storage device along the second pipeline and flow into Proportioning device 6, when the second switch 3 is closed, the first gas can flow out from the storage device for the first gas, and the first gas cannot flow along the second pipeline and flow into the proportioning device 6. At this time, the first gas The second pipeline is in a closed state. The second switch 3 can be a shut-off valve, or a solenoid valve, or other valves capable of opening and closing the pipeline. Select according to actual needs. No specific requirements are made here. Preferably, In this embodiment, the second switch 3 is a solenoid valve, which is a commercially available product, and is selected according to actual needs, and no specific requirements are made here.

The above-mentioned second flow detection device 4 is used to detect the flow of the first gas in the second pipeline, and the second flow detection device 4 is a flow meter. Preferably, in this embodiment, the second flow detection device 4 is The mass flowmeter is a commercially available product, which is selected according to actual needs, and no specific requirements are made here.

The above-mentioned pressure regulating device 5 is used to regulate the pressure of the first gas flowing out from the storage device for the first gas. In this embodiment, the pressure of the first gas located in the storage device for the first gas is relatively high. The first gas flowing out from the device is decompressed so that the pressure of the first gas in the second pipeline is less than 0.5 MPa. Therefore, the pressure regulating device 5 is preferably a pressure reducing valve. The first gas flowing out of the storage device is decompressed so that the decompressed first gas flows along the second pipeline. The decompression valve is a commercially available product, which is selected according to actual needs, and no specific requirements are made here.

The above-mentioned first gas is a mixed gas of phosphine and argon.

In this embodiment, preferably, the pressure regulating device 5 , the second flow detection device 4 and the second switch 3 are sequentially arranged along the flow direction of the first gas.

When the automatic ventilation system is in use, the first flow detection device 1, the first switch 2, the second switch 3, the second flow detection device 4, and the pressure regulating device 5 are all connected to the control system of the single crystal furnace. Pulling process, single crystal pulling, the control system controls the action of the first switch 2, opens the first gas path, and continuously feeds argon into the single crystal furnace during the single crystal pulling process, and argon is used as a protective gas , to take away impurities during the crystal pulling process; when the doping gas needs to be introduced, the control system controls the pressure regulating device 5 and the second switch 3 to operate, and performs the introduction of the first gas containing phosphine and argon, And through the first flow detection device 1 and the second flow detection device 4 respectively measure the flow of argon in the first gas path and the flow of the first gas in the second gas path, and according to the first flow detection device 1 and the second flow The detection result of the second flow detection device 4, the control system controls the action of the first switch 2 and the second switch 3, and controls the flow rate of the argon gas and the flow rate of the first gas, so that the argon gas and the first gas flow in the proportioning device according to the required flow rate. 6 for proportioning, the proportioned gas flows out from the proportioning device 6 and enters the single crystal furnace for meteorological doping. At the same time, the flow rate of the protective gas argon is also maintained to ensure the smooth pulling of the single crystal Carry out; wherein, after the first gas flows out from the first gas storage device, it is decompressed under the action of the pressure regulating device 5 to reduce the pressure of the gas, and the decompressed first gas flows in the second gas path; The control system controls the flow rate of the doping gas according to the single crystal pulling process, so that the flow rate of the doping gas increases with the attenuation of the resistivity of the single crystal during the single crystal pulling process, and controls the attenuation of the axial resistivity of the single crystal.

A specific example will be used below to illustrate.

In the Czochralski single crystal process, the control system is preset with a well-edited crystal pulling process program, and the gas doping start node and gas flow rate are set in the program. In this embodiment, the doping gas doping start node is When entering the equal-diameter stage, the dopant gas will be introduced. When the dopant gas starts to be introduced, the flow rate of the dopant gas will be 0.6L/min;

The single crystal is pulled according to the crystal pulling process procedure. In the chemical material stage, crystal seeding stage, shoulder expansion stage, and shoulder turning stage, the control system controls the first gas path of the automatic ventilation system to maintain the ventilation state, and continuously ventilates into the single crystal furnace. Enter the protective gas argon to take away the impurities generated during the Czochralski single crystal process; when the Czochralski single crystal enters the equal-diameter stage, the control system judges that it meets the set doping gas opening node and flow conditions, and the control system controls the automatic ventilation action , the second gas path is kept in a ventilated state, the mixed gas of phosphine and argon is continuously passed into the single crystal furnace, and the Czochralski single crystal is doped with phosphorus;

During the feeding process of phosphine and argon mixed gas, as the length of the single crystal increases, the axial resistivity of the single crystal gradually decays. According to the decay law of the axial resistivity of the single crystal, the phosphine and The flow rate of the mixed gas of argon is gradually increased to suppress the decay rate of the axial resistivity of the single crystal, specifically,

Measure the contact voltage between the single crystal and the melt in the crucible, and calculate the single crystal resistivity according to the relationship between the contact voltage and the single crystal resistivity, wherein,

When the axial resistivity of the single crystal is 0.8Ω·cm/m, the flow rate of the mixed gas of phosphine and argon is 0.12L/min;

When the axial resistivity of the single crystal decreases to 0.7Ω cm/m, the flow rate of the mixed gas of phosphine and argon increases to 0.16L/min;

When the axial resistivity of the single crystal is reduced to 0.65Ω·cm/m, the flow rate of the mixed gas of phosphine and argon is increased to 0.20L/min;

When the axial resistivity of the single crystal decreases to 0.6Ω cm/m, the flow rate of the mixed gas of phosphine and argon increases to 0.24L/min;

When the axial resistivity of the single crystal decreases to 0.54Ω·cm/m, the flow rate of the mixed gas of phosphine and argon increases to 0.28L/min;

When the axial resistivity of the single crystal is reduced to 0.5Ω·cm/m, the flow rate of the mixed gas of phosphine and argon is increased to 0.32L/min;

When the axial resistivity of the single crystal decreases to 0.43Ω·cm/m, the flow rate of the mixed gas of phosphine and argon increases to 0.36L/min;

When the axial resistivity of the single crystal is reduced to 0.4Ω·cm/m, the flow rate of the mixed gas of phosphine and argon is increased to 0.40L/min;

After the end of the isodiametric stage, the mixed gas of phosphine and argon continues to be introduced. At this time, the flow rate of the mixed gas is the mixed flow rate at the end of the isodiametric stage. Keep this flow until the end of the final stage. Phosphine and argon The mixed gas of argon ends the feeding;

Single crystal pulling continues until single crystal pulling is complete.

The flow rate of the mixed gas of phosphine and argon and the change of the axial resistivity of the single crystal are analyzed, as shown in the following table:

From the analysis of the above data, it can be known that in the process of pulling gallium-doped single crystal, the mixed gas containing phosphorus element is passed into the single crystal furnace as the dopant gas, and according to the difference between the single crystal and the melt of different weights in the crucible, The contact voltage is used to calculate the resistivity of the single crystal, so as to know the law of the axial resistivity decay of the single crystal; In , set the node and flow rate at which the doping gas starts to pass in. When the opening conditions are met, the automatic ventilation system is controlled to control the automatic feeding of the doping gas, and the flow rate of the doping gas is controlled to automatically carry out doping with the doping gas. The attenuation rate of the axial resistivity of the single crystal is suppressed. Compared with the existing doping without doping gas, the attenuation rate of the axial resistivity of the single crystal is slowed down and effectively controlled.

Due to the adoption of the above-mentioned technical scheme, in the crystal pulling process of Czochralski single crystal, the conditions for the doping gas to start doping are set. When the set conditions are met, the control system controls the action of the automatic ventilation system, and the doping gas is introduced into the single crystal furnace; the resistance of the single crystal in different periods is calculated according to the contact voltage between the single crystal and the melt of different weights in the crucible Rate, and according to the change of the resistivity of the single crystal, automatically control the change of the flow rate of the dopant gas, thereby controlling the axial attenuation of the resistivity of the single crystal, so that the attenuation of the axial resistivity of the single crystal is slow; the axis of the single crystal The axial resistivity can realize automatic control, automatically measure and calculate the resistivity of the head, and automatically control the axial attenuation of the single crystal resistivity according to the resistivity of the head; the automatic ventilation system is simple in structure, easy to develop, and will not affect the crystal pulling equipment of the single crystal furnace The structure is modified, and the input cost is low; the resistivity of the single crystal is controlled according to the axial attenuation law of the resistivity of the single crystal, and the distribution range of the resistivity of the single crystal can be customized according to the demand.

The embodiments of the present invention have been described in detail above, but the content described is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (10)

1. A method for automatically controlling the resistivity of single crystal silicon, characterized in that: gas doping is carried out in the Czochralski single crystal process, comprising: Set gas doping open node and gas flow rate; Performing single crystal pulling, during the single crystal pulling process, obtaining the contact voltage of the melt in the crucible, and automatically calculating the single crystal resistivity according to the contact voltage; Judging the single crystal pulling process, if the set gas doping start node condition is met, the control gas is input into the single crystal furnace for doping; at the same time, the flow rate of the gas is controlled according to the calculated single crystal resistivity, and the single crystal axis is controlled. resistivity; Otherwise, no gas is input into the single crystal furnace. 2. The method for automatically controlling the resistivity of single crystal silicon according to claim 1, characterized in that: the gas doping start node is when single crystal pulling enters the shoulder expansion stage or the equal diameter stage. 3. The method for automatically controlling the resistivity of single crystal silicon according to claim 2, characterized in that: the gas flow rate is 0-1 L/min. 4. The method for automatically controlling the resistivity of single crystal silicon according to claim 1, wherein the gas is a mixed gas of phosphine and argon. 5. The method for automatically controlling the resistivity of single crystal silicon according to any one of claims 1-4, characterized in that: said control of the flow rate change of the gas according to the calculated resistivity of the single crystal comprises: As the resistivity of the single crystal decreases, the flow rate of the gas gradually increases. When the resistivity of the single crystal decreases by one resistivity variation, the gas flow increases by one flow variation to control the attenuation of the axial resistivity of the single crystal. 6. The method for automatically controlling the resistivity of single crystal silicon according to claim 5, characterized in that: the variation of the resistivity is 0-1Ω·cm/m, and the variation of the flow rate of the gas is 0-1L/m min. 7. The method for automatically controlling the resistivity of single crystal silicon according to any one of claims 1-4 and 6, characterized in that the concentration of the gas is 1000-10000 ppm. 8 . The method for automatically controlling the resistivity of single crystal silicon according to claim 1 , wherein the gas is mixed with argon gas and the first gas according to a certain flow ratio. 9 . The method for automatically controlling the resistivity of single crystal silicon according to claim 8 , wherein the ratio of the flow rate of the argon gas to the first gas is 2:1-10:1. 10. The method for automatically controlling the resistivity of single crystal silicon according to claim 8 or 9, characterized in that the first gas is a mixed gas of argon and phosphine.

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