Method for reducing accumulation of heavily doped single crystal oxide

Abstract

The invention provides a method for reducing accumulation of heavily-doped single crystal oxides, and belongs to the technical field of heavily-doped crystal pulling control methods, in the whole crystal pulling process, a second discharge part is always opened, during doping, a blowing part and a first discharge part are opened, the blowing part generates a plurality of downward inlet air flows, and the first discharge part is used for discharging the heavily-doped single crystal oxides. And a plurality of air flows generated by the blowing part and a relatively large amount of argon in the furnace generate relatively large air pressure, so that upwards-volatilized gas in the furnace is turned downwards, and then the volatilized gas is discharged through the short-path first discharge part, so that a large amount of oxides are prevented from being adhered to the water-cooled jacket, crystal growth is not influenced, and the service life of the water-cooled jacket is prolonged. Therefore, the leading and releasing times of the heavily doped single crystal are reduced, and the crystallization rate is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heavy doping crystal pulling method, and particularly relates to a method for reducing accumulation of heavy doping single crystal oxide. BACKGROUND

[0002] Heavy doping single crystal silicon has volatility, including arsenic, red phosphorus and antimony, and the volatilization effects of the doping elements are different due to the differences in physical properties of the doping elements, wherein the volatilization amount generated under the same process and time is generally red phosphorus> arsenic> antimony.

[0003] When the size of the produced single crystal is larger, the size of the matched thermal field is increased, and generally, in order to accelerate cooling, a water cooling mechanism, such as a water cooling jacket, is added above the thermal zone, the water cooling jacket is suspended below the isolation valve, and a water cooling screen is additionally installed in the heat shield, so as to accelerate cooling faster; however, due to the characteristic that red phosphorus is easily adhered in the range of 400 DEG C to 600 DEG C, the red phosphorus gas in the doping process is easily adhered to the water cooling jacket with lower temperature, and the adhered red phosphorus gas is in the form of granular oxide, and when the thickness of the oxide adhered to the water cooling mechanism is greater than 1mm after a period of time, the oxide is dropped into the melt along with argon gas in the process of crystal pulling, so as to damage the single crystal structure and become polycrystal, and more seriously, the liquid surface crystallization cannot be used for crystal pulling. SUMMARY

[0004] Therefore, the present application provides a method for reducing accumulation of heavy doping single crystal oxide.

[0005] The present application adopts the technical scheme for solving the technical problems: A method for reducing accumulation of heavy doping single crystal oxide, the method comprises the following steps: performing crystal pulling through a predetermined thermal field, the predetermined thermal field comprises a furnace body, a water cooling jacket, a heat shield, a heat insulation material and an oxide discharging assembly, the oxide discharging assembly comprises a blowing part, a first discharging part and a second discharging part, the water cooling jacket, the heat shield and the heat insulation material are located in the furnace body, the blowing part, the first discharging part and the second discharging part are located outside the furnace body, the furnace body, the water cooling jacket, the heat shield and the heat insulation material are coaxial, the water cooling jacket is located below the first blowing part, the water cooling jacket is located above the heat shield, the heat insulation material is located in the circumferential direction of the heat shield, the first discharging part is located on one side of the heat shield, the second discharging part is located at the bottom of the furnace body, the heat shield is connected with the heat insulation material, the blowing part is connected with the furnace body, and gas is blown into the furnace body, the first discharging part is in communication with the heat insulation material and the furnace body, and the second discharging part is in communication with the bottom of the furnace body, so as to discharge the oxide from the upper part of the furnace body and the bottom of the furnace body. In the whole process of crystal pulling, the second discharging part is always opened, and the blowing part and the first discharging part are opened again during doping, so as to control the gas flow in the furnace, and make the volatilized gas change direction and be taken away.

[0006] Preferably, the blowing part comprises a flange, an air pipe, the flange is internally provided with an annular cavity, the inner side of the flange is uniformly provided with a plurality of argon gas inlets, the air pipe is provided with an inlet valve, the argon gas inlets are arranged in two rows, the two rows of argon gas inlets are staggered, the argon gas inlets are communicated with the annular cavity, and the air pipe is connected with the flange to communicate with the annular cavity. When the first doping is performed, the inlet valve is opened, argon gas is introduced, and the volatile gas in the furnace is diverted.

[0007] Preferably, the argon gas inlets are distributed at 15°-60° on the circumference of the flange, the argon gas inlets are arranged obliquely, the direction of the argon gas inlets is downward, and the angle between the argon gas inlets and the horizontal direction is 30°-45°.

[0008] Preferably, the flow rate of the argon gas is >100 slm.

[0009] Preferably, the first discharge part is two, the first discharge parts are symmetrically arranged on the two sides of the furnace body, the first discharge part comprises a first discharge pipe, a first valve and a first discharge pump, the upper part of the heat insulation material is provided with a first through hole, the furnace body is also provided with a second through hole, the first through hole of the heat insulation material is close to the upper part of the heat shield, the first through hole of the heat insulation material is coaxial with and the same size as the second through hole of the furnace body, one end of the first discharge pipe passes through the second through hole of the furnace body, the first through hole of the heat insulation material and the gap between the heat shield and the heat insulation material to communicate, the first valve is connected with the first discharge pipe, and the other end of the first discharge pipe is connected with the first discharge pump. When the first doping is performed, the first valve is opened, and the oxide is discharged from the upper part of the furnace body through the first discharge pump, and when the first doping is completed, the first valve is closed.

[0010] Preferably, if the supplementary doping is needed, when the supplementary doping amount is greater than 4.5 times the feeding amount, the inlet valve is opened, argon gas is introduced, the volatile gas in the furnace is diverted, and the first valve is opened, and the oxide is discharged from the upper part of the furnace body through the first discharge pump, and when the supplementary doping amount is less than or equal to 4.5 times the feeding amount, the inlet valve and the first valve are closed, and only the second discharge part is used to discharge the oxide.

[0011] Preferably, the second discharge part comprises a second discharge pipe, a second valve and a second discharge pump, one end of the second discharge pipe is communicated with the bottom of the furnace body, the second valve is connected with the second discharge pipe, and the other end of the second discharge pipe is connected with the second discharge pump. During the crystal pulling process, the second valve is always opened, and the oxide is discharged from the lower part of the furnace body.

[0012] Preferably, the doping process, the liquid port distance is less than or equal to 90mm, and the argon flow rate is greater than or equal to 110slm.

[0013] Preferably, the second valve is an angle valve, and the aperture of the angle valve is φ5mm, and the angle valve opening is less than 40°.

[0014] Compared with the prior art, the present application has the beneficial effects that: The present application is characterized in that: a predetermined thermal field is used for crystal pulling, the predetermined thermal field comprises a furnace body, a water cooling jacket, a heat shield, a heat insulation material, and an oxide discharge assembly, the oxide discharge assembly comprises a blowing part, a first discharge part, and a second discharge part, the water cooling jacket, the heat shield, and the heat insulation material are located inside the furnace body, the blowing part, the first discharge part, and the second discharge part are located outside the furnace body, the furnace body, the water cooling jacket, the heat shield, and the heat insulation material are coaxial, the water cooling jacket is located below the first blowing part, the water cooling jacket is located above the heat shield, the heat insulation material is located in the circumferential direction of the heat shield, the first discharge part is located on one side of the heat shield, the second discharge part is located at the bottom of the furnace body, the heat shield is connected with the heat insulation material, the blowing part is connected with the furnace body, the first discharge part is in communication with the heat insulation material and the furnace body, and the second discharge part is in communication with the bottom of the furnace body; during the entire crystal pulling process, the second discharge part is always open, and when doping, the blowing part and the first discharge part are additionally opened, the blowing part generates a plurality of downward gas streams, and the plurality of gas streams generated by the blowing part generate a large gas pressure with a large amount of argon in the furnace, so that the direction of the gas volatilized upward in the furnace is changed to downward, and then the volatilized gas is discharged through the short-path first discharge part, thereby avoiding a large amount of oxide from adhering to the water cooling jacket, and further avoiding affecting the crystal growth, so that the number of ignition of the heavy doping single is reduced, and the crystal formation rate is improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a structure diagram of the predetermined thermal field.

[0016] Figure 2 is a structure diagram of the flange.

[0017] Figure 3 is a structure diagram of the thermal field in the comparative example.

[0018] Figure 4 is a comparison diagram of the ignition number of the embodiment and the comparative example.

[0019] Figure 5 is a comparison diagram of the crystal formation rate of the embodiment and the comparative example.

[0020] In the diagram: Pre-designated hot zone 10, furnace body 100, water-cooled jacket 200, heat shield 300, heat insulation material 400, blowing section 510, flange 511, argon gas inlet 5111, vent pipe 512, inlet valve 5121, first discharge section 520, first discharge pipe 521, first valve 522, first discharge pump 523, second discharge section 530, second discharge pipe 531, second valve 532, second discharge pump 533. Detailed Implementation

[0021] The technical solution and effects of the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] Please refer to Figure 1 and Figure 2 A method for reducing the accumulation of heavily doped single-crystal oxides involves crystal pulling through a predetermined hot zone 10. The predetermined hot zone 10 includes a furnace body 100, a water-cooled jacket 200, a heat shield 300, a heat insulation material 400, and an oxide discharge assembly. The oxide discharge assembly includes a blowing section 510, a first discharge section 520, and a second discharge section 530. The water-cooled jacket 200, heat shield 300, and heat insulation material 400 are all located inside the furnace body 100. The blowing section 510, first discharge section 520, and second discharge section 530 are located outside the furnace body 100. The furnace body 100, water-cooled jacket 200, heat shield 300, and heat insulation material 400 are coaxial. The water-cooled jacket 200 is located below the first blowing section 510. Located above the heat shield 300, which is located inside the heat insulation material 400 and circumferentially around the heat shield 300, the first discharge part 520 is located on one side of the heat shield 300, and the second discharge part 530 is located at the bottom of the furnace body 100. The water cooling jacket 200 is connected to the furnace body 100, the heat shield 300 is connected to the heat insulation material 400, and the blowing part 510 is connected to the furnace body 100 to blow gas into the furnace body 100. The first discharge part 520 is connected to the heat insulation material 400 and the furnace body 100, and the second discharge part 530 is connected to the bottom of the furnace body 100 to discharge oxides from the upper part and the bottom of the furnace body 100. Throughout the crystal pulling process, the second discharge section 530 remains open. During doping, the blowing section 510 and the first discharge section 520 are opened again to control the gas flow inside the furnace, so that the volatile gas is carried away by changing its direction.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: The application is characterized in that the crystal pulling is carried out through a predetermined thermal field 10, the predetermined thermal field 10 comprises a furnace body 100, a water cooling jacket 200, a heat shield 300, a heat insulation material 400, and an oxide discharging assembly, the water cooling jacket 200, the heat shield 300, and the heat insulation material 400 are located in the furnace body 100, the blowing part 510, the first discharging part 520, and the second discharging part 530 are located outside the furnace body 100, the furnace body 100, the water cooling jacket 200, the heat shield 300, and the heat insulation material 400 are coaxial, the water cooling jacket 200 is located below the first blowing part 510, the water cooling jacket 200 is located above the heat shield 300, the heat insulation material 400 is located in the circumference of the heat shield 300, the first discharging part 520 is located on one side of the heat shield 300, the second discharging part 530 is located at the bottom of the furnace body 100, the heat shield 300 is connected with the heat insulation material 400, the blowing part 510 is connected with the furnace body 100, the first discharging part 520 is communicated with the heat insulation material 400 and the furnace body 100, and the second discharging part 530 is communicated with the bottom of the furnace body 100; during the whole crystal pulling process, the second discharging part 530 is always opened, and when doping, the blowing part 510 and the first discharging part 520 are also opened, the blowing part 510 generates a plurality of downward gas flows, and the plurality of gas flows generated by the blowing part 510 and a large amount of argon in the furnace generate a large gas pressure, so that the direction of the gas volatilized upward in the furnace is changed to downward, and then the volatilized gas is discharged through the short-path first discharging part 520, so that the adhesion of the oxide on the water cooling jacket 200 is avoided, the growth of the crystal is not affected, the number of ignition of the heavy doping single is reduced, and the crystal formation rate is improved.

[0024] The whole crystal pulling process comprises material melting, high-temperature treatment, stabilization, first doping, temperature test, crystal growth, or material melting, high-temperature treatment, stabilization, first doping, temperature test, crystal growth, NG remelting, additional doping, temperature test, and crystal growth, during the crystal pulling process, the second discharging part 530 forms a long-path lower exhaust at the bottom of the furnace body 100, and the blowing part 510 and the first discharging part 520 form a short-path upper exhaust, the second discharging part 530 is always opened during the crystal pulling process, and when first doping, the blowing part 510 and the first discharging part 520 are opened, the argon gas blown in through the blowing part 510 changes the direction of the volatile gas, so that the volatile gas is carried by the argon gas and is drawn away by the first discharging part 520 after passing through the liquid surface through the heat shield 300, so as to make up for the loss of suction caused by the long path of the second discharging part 530, and a large amount of volatile gas is carried away, so that the accumulation of the oxide is avoided to affect the growth of the crystal, and when the first doping is completed, the blowing part 510 and the first discharging part 520 are closed, so as to avoid the blocking of the oxide at the position of the first discharging part 520 in the subsequent stage, thereby affecting the subsequent crystal growth.

[0025] Take the heavily doped red phosphorus as an example, because the amount of doping is larger when first doped, the amount of oxide adhered is also the largest, if only the second discharge part 530 is used to discharge the oxide, the argon gas passes through the liquid surface of the heat shield 300 and is sucked away by the second discharge pump 533 at the bottom of the heater, the path is longer, resulting in insufficient suction, a large amount of red phosphorus volatilized during the first doping is difficult to be completely removed, after calculation, at least 40% or more of the volatile gas adheres to the inner wall of the furnace and the water cooling jacket 200, therefore, the first discharge part 520 needs to be designed to increase the new discharge path.

[0026] Further, the blowing part 510 includes a flange 511 and a vent pipe 512, the flange 511 is internally provided with an annular cavity, a plurality of argon gas inlet holes 5111 are uniformly arranged on the inner side of the flange 511, the vent pipe 512 is provided with an inlet valve 5121, the argon gas inlet holes 5111 are arranged in two rows, the two rows of argon gas inlet holes 5111 are staggered, the argon gas inlet holes 5111 are in communication with the annular cavity, the argon gas inlet holes 5111 are in communication with the inside of the furnace body 100, and the vent pipe 512 is connected with the flange 511 to communicate with the annular cavity, so as to blow gas into the furnace body 100; When first doping is performed, the inlet valve 5121 is opened, argon gas is introduced, and the volatile gas in the furnace is diverted.

[0027] Specifically, the flange 511 can be installed in the isolation valve of the single crystal furnace, and the isolation valve is connected with the furnace body 100, for example, the installation method of the second flange 511 in the Chinese invention with the application number 202310899965.8 is consistent.

[0028] Further, the argon gas inlet holes 5111 are distributed on the circumference of the flange 511 at an angle of 15°-60°, the argon gas inlet holes 5111 are arranged obliquely, the direction of the argon gas inlet holes is downward, and the angle between the argon gas inlet holes and the horizontal direction is 30°-45°, so as to form a downward gas pressure area to make the upward volatilization turn downward, the direction of the inlet is too small, and the gas pressure area cannot cover the middle, and the direction of the inlet is too large, and the strength of the gas pressure area is not enough.

[0029] Further, the argon gas inlet holes 5111 are distributed on the circumference of the flange 511 at an angle of 15°-30°.

[0030] Further, the flow rate of the argon gas is >100 slm, so as to increase the flow of the argon gas during doping, change the gas flow in the furnace, and generate a large gas pressure with the argon gas in the furnace itself, so as to force the volatile gas to change direction.

[0031] Further, the first exhaust part 520 is two, the first exhaust part is symmetrically arranged on both sides of the furnace body 100, the first exhaust part 520 includes a first exhaust pipe 521, a first valve 522, a first exhaust pump 523, the upper part of the heat insulation material 400 is provided with a first through hole, the furnace body 100 is also provided with a second through hole, the first through hole of the heat insulation material 400 is close to the upper part of the heat shield 300, the first through hole of the heat insulation material 400 is coaxial with the second through hole of the furnace body 100 and the size is the same, one end of the first exhaust pipe 521 passes through the second through hole of the furnace body 100, the first through hole of the heat insulation material 400 and the gap between the heat shield 300 and the heat insulation material 400 to communicate, the first valve 522 is connected with the first exhaust pipe 521, the other end of the first exhaust pipe 521 is connected with the first exhaust pump 523; By setting a new exhaust path on the original exhaust path, the flow direction of the volatile gas is changed during the doping process.

[0032] When the first doping is carried out, the first valve 522 is opened, and the oxide is discharged from the upper part of the furnace body 100 through the first exhaust pump 523, when the first doping is finished, the first valve 522 is closed, to avoid the oxide from blocking in the first exhaust pipe 521, thereby affecting the subsequent crystal growth.

[0033] Further, if the supplement doping is needed, when the supplement doping amount is greater than 4.5 times the feeding amount, the inlet valve 5121 is opened, argon is introduced, the volatile gas in the furnace is diverted, and the first valve 522 is opened, the oxide is discharged from the upper part of the furnace body 100 through the first exhaust pump 523, when the supplement doping amount is less than or equal to 4.5 times the feeding amount, the inlet valve 5121 and the first valve 522 are closed, and only the second exhaust part 530 is used to discharge the oxide.

[0034] Further, the second exhaust part 530 includes a second exhaust pipe 531, a second valve 532, a second exhaust pump 533, one end of the second exhaust pipe 531 is communicated with the bottom of the furnace body 100, the second valve 532 is connected with the second exhaust pipe 531, the other end of the second exhaust pipe 531 is connected with the second exhaust pump 533; During the crystal pulling process, the second valve 532 is always opened, and the oxide is discharged from the lower part of the furnace body 100.

[0035] Further, during the doping process, the liquid port distance is less than or equal to 90 mm, and the argon flow is greater than or equal to 110 slm, which refers to the flow of argon which is always opened in the furnace.

[0036] Further, the second valve 532 is an angle valve, the aperture of the angle valve is φ5mm, the angle valve opening is <40°, so as to ensure the doping pressure, and the gas has a fast flow rate when passing above the liquid surface, and then the first exhaust pump 523 is opened, and the volatile gas is quickly taken away. Embodiment

[0037] An 8-inch predetermined thermal field 10 as shown in Figure 1 , 2 is used to draw an 8-inch heavily doped red phosphorus crystal rod, the doping amount is 800g, the feeding amount is 160Kg, the crystal drawing parameters are as follows: crystal rotation: 10rpmm; crucible rotation: 2rpm; pressure: 20Kpa; argon: 130slm; MCZ; Gap: 40mm.

[0038] The parameter setting during doping is as follows: doping device: single layer quartz bell jar; Gap: 90mm; pressure: 20Kpa; argon delivered in the gas pipe 512: 130slm, and then material melting, high temperature treatment, stabilization, doping, test temperature, crystal pulling and crystal growth are carried out, and the experiment is carried out for 10 times.

[0039] Comparative example: The same crystal rod as in the embodiment is drawn using a thermal field (without blowing part and first exhaust part) as shown in Figure 3 .

[0040] The crystal drawing parameters are as follows: crystal rotation: 10rpmm; crucible rotation: 2rpm; pressure: 20Kpa; argon: 130slm; MCZ; Gap: 40mm.

[0041] The parameter setting during doping is as follows: doping device: single layer quartz bell jar; Gap: 90mm; pressure: 20Kpa; argon delivered in the gas pipe 512: 130slm, and then material melting, high temperature treatment, stabilization, doping, test temperature, crystal pulling and crystal growth are carried out, and the experiment is carried out for 10 times.

[0042] The ignition and discharge times and the crystal formation rate of the crystal rods drawn by the method of the embodiment and the comparative example are as shown in Figure 4 , 5 , wherein the average ignition and discharge times of the comparative example is 5.1; the average ignition and discharge times of the embodiment is 2.8; the average crystal formation rate of the comparative example is 66.5%; and the average crystal formation rate of the embodiment is 73.4%, it can be seen that the modified thermal field and the control method can effectively reduce the problems of high crystal pulling ignition and discharge times and low crystal formation rate caused by the accumulation of red phosphorus oxides.

[0043] The above disclosure is merely the preferred embodiments of the present application, and of course cannot be used to limit the scope of the present application, and those skilled in the art can understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made according to the claims of the present application, still belong to the scope covered by the present application.

Claims

1. A method of reducing heavy doped single crystal oxide buildup, comprising: The crystal is drawn by a predetermined thermal field, the predetermined thermal field comprises a furnace body, a water cooling jacket, a heat shield, a heat insulation material, and an oxide discharging assembly, the oxide discharging assembly comprises a blowing part, a first discharging part, and a second discharging part, the water cooling jacket, the heat shield, and the heat insulation material are located in the furnace body, the blowing part, the first discharging part, and the second discharging part are located outside the furnace body, the furnace body, the water cooling jacket, the heat shield, and the heat insulation material are coaxial, the water cooling jacket is located below the first blowing part, the water cooling jacket is located above the heat shield, the heat insulation material is located in the circumference of the heat shield, the first discharging part is located on one side of the heat shield, the second discharging part is located at the bottom of the furnace body, the heat shield is connected with the heat insulation material, the blowing part is connected with the furnace body, gas is blown into the furnace body, the first discharging part is communicated with the heat insulation material and the furnace body, and the second discharging part is communicated with the bottom of the furnace body, so as to discharge the oxide from the upper part and the bottom of the furnace body; During the whole crystal drawing process, the second discharging part is always opened, and when doping, the blowing part and the first discharging part are opened again to control the gas flow in the furnace, so that the volatilized gas is converted and carried away.

2. The method of reducing heavy doped single crystal oxide buildup of claim 1, wherein, The blowing part comprises a flange and a gas pipe, an annular cavity is formed in the flange, a plurality of argon gas inlets are uniformly arranged on the inner side of the flange, an inlet valve is arranged on the gas pipe, the argon gas inlets are arranged in two rows, the two rows of argon gas inlets are arranged alternately, the argon gas inlets are communicated with the annular cavity, and the gas pipe is connected with the flange to communicate with the annular cavity. When the first doping is performed, the inlet valve is opened, argon gas is introduced, and the volatile gas in the furnace is diverted.

3. The method of reducing heavy doped single crystal oxide buildup of claim 2, wherein, The argon gas inlets are distributed at an angle of 15°-60° on the circumference of the flange, the argon gas inlets are arranged obliquely, the direction of the argon gas inlets is downward, and the angle between the argon gas inlets and the horizontal direction is 30°-45°.

4. The method of reducing heavy doped single crystal oxide buildup of claim 3, wherein, The flow rate of the argon gas is greater than 100 slm.

5. The method of reducing heavy doped single crystal oxide buildup of claim 1 or 4, wherein, The first discharging part is two, the first discharging parts are symmetrically arranged on the two sides of the furnace body, the first discharging part comprises a first discharging pipe, a first valve, and a first discharging pump, the upper part of the heat insulation material is provided with a first through hole, the furnace body is also provided with a second through hole, the first through hole of the heat insulation material is close to the upper part of the heat shield, the first through hole of the heat insulation material is coaxial with the second through hole of the furnace body and has the same size, one end of the first discharging pipe passes through the second through hole of the furnace body, the first through hole of the heat insulation material, and the gap between the heat shield and the heat insulation material to communicate, the first valve is connected with the first discharging pipe, and the other end of the first discharging pipe is connected with the first discharging pump. When the first doping is performed, the first valve is opened, and the oxide is discharged from the upper part of the furnace body by the first discharging pump, and when the first doping is completed, the first valve is closed.

6. The method of reducing heavy doped single crystal oxide buildup of claim 5, wherein, If the supplement is needed, when the supplement is greater than 4.5 times the feeding amount, open the inlet valve, pass in argon, divert the volatile gas in the furnace, open the first valve, and discharge the oxide from the upper part of the furnace body through the first discharge pump; when the supplement is less than or equal to 4.5 times the feeding amount, close the inlet valve and the first valve, and only discharge the oxide through the second discharge part.

7. The method of reducing heavy doped single crystal oxide buildup of claim 1 or 6, wherein, The second discharge part comprises a second discharge pipe, a second valve and a second discharge pump, one end of the second discharge pipe is communicated with the bottom of the furnace body, the second valve is connected with the second discharge pipe, and the other end of the second discharge pipe is connected with the second discharge pump. During the crystal pulling process, the second valve is always open to discharge the oxide from the lower part of the furnace body.

8. The method of reducing heavy doped single crystal oxide buildup of claim 7, wherein, During the doping process, the distance between the liquid port and the furnace body is less than or equal to 90 mm, and the argon flow is greater than or equal to 110 slm.

9. The method of reducing heavy doped single crystal oxide buildup of claim 8, wherein, The second valve is an angle valve, the aperture of the angle valve is φ5 mm, and the opening of the angle valve is less than 40°.

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