System and method for reducing oxygen content of Czochralski single crystal

Abstract

The invention belongs to the technical field of semiconductor material preparation, and particularly relates to a system and a method for reducing the oxygen content of a Czochralski single crystal, after material melting, most gas in a single crystal furnace is distributed into a gas collecting cavity through a gas inlet part, the gas in the gas collecting cavity can be exhausted through a gas exhaust part, and the oxygen content of the Czochralski single crystal is reduced through a quartz gas exhaust system. The flow-out speed of gas in the single crystal furnace can be effectively controlled, so that the volatilization rate of Oi is controlled, the exhaust capacity of a vacuum pump is improved, more volatile O elements can be taken away, the O elements are prevented from flowing into the front edge of a solid-liquid interface, finally, the O content is reduced, the oxygen content in a single crystal silicon rod is stably controlled to be lower than 5 ppma, and the oxygen content of the single crystal silicon rod is reduced while the O content is controlled. When the gas collection cavity collects gas, radiant heat absorbed by the surface of the upper half part of the heat insulation assembly and heat brought by fluid flowing can be taken away through gas flowing, a more excellent temperature field is provided, and therefore nucleation and growth of defects in a crystal bar are controlled.

Description

Technical Field

[0001] The present invention belongs to the technical field of semiconductor material preparation, and in particular relates to a system and method for reducing the oxygen content of a CZ single crystal. Background Art

[0002] Single crystal silicon is an important semiconductor material, widely used in the fields of microelectronics and optoelectronics, especially in the manufacture of integrated circuits. The quality of single crystal silicon has a direct impact on the performance of the final product. In the growth process of single crystal silicon, oxygen is one of the most common impurities. It will form a silicon-oxygen complex in the silicon crystal, affecting the electrical properties and mechanical stability of the material. Therefore, the preparation of single crystal silicon with low oxygen content is crucial to improving device performance.

[0003] Oxygen exists in various forms in single crystal silicon. Some oxygen atoms exist in interstitial form, forming Si-O-Si bonds. In the production process of CZ single crystal silicon, the main source of oxygen impurities is the dissolution of quartz crucible. Silicon reacts with quartz crucible at high temperature to generate SiO, of which about 1% will enter the molten silicon. The oxygen content in the prepared single crystal silicon is relatively high, which cannot meet the requirements of single crystal silicon with an oxygen content of less than 5ppma in the IGBT chip manufacturing process. Summary of the invention

[0004] In view of this, the present invention provides a system and method for reducing the oxygen content of Czochralski single crystals to solve the technical problem that the oxygen content of Czochralski single crystal silicon produced in the prior art is relatively high and cannot meet the requirement of single crystal silicon with an oxygen content lower than 5ppma in the IGBT chip manufacturing process.

[0005] To achieve the above objectives, this application adopts the following scheme:

[0006] A system for reducing the oxygen content of a CZ single crystal comprises a single crystal furnace and a heater, and further comprises: a crucible, a heat insulation component, a quartz exhaust system arranged in the single crystal furnace, and a graphite exhaust system arranged at the bottom of the single crystal furnace, wherein:

[0007] The heater is disposed around the crucible and is used to heat and melt the silicon material contained in the crucible;

[0008] The heat insulation component is located above the crucible, and the heat insulation component includes a heat insulation upper section and a heat insulation lower section;

[0009] The quartz exhaust system is arranged above the lower insulation section, and the quartz exhaust system includes an air inlet, an outer ring, an inner ring and at least one exhaust member. A gas collecting chamber is formed between the outer ring and the inner ring. The air inlet is connected to the gas collecting chamber and the exhaust member. Exhaust holes are opened on the single crystal furnace corresponding to the exhaust member. The exhaust holes are connected to a vacuum pump, and the exhaust member is connected to the other end of the vacuum pump. A pressure detection device is arranged at the exhaust hole, and the pressure detection device is used to detect the pressure in the gas collecting chamber.

[0010] Preferably, the air inlet member is arranged to be inclined inwardly along the cavity opening at one end of the gas collecting cavity, and a plurality of evenly distributed air inlet holes are provided on the air inlet member.

[0011] Preferably, the height between the outer ring and the inner ring is 300 mm to 600 mm.

[0012] Preferably, an outer wall of the quartz exhaust system and an inner wall of the thermal insulation component have a first gap, and the first gap is 1 mm to 20 mm.

[0013] Preferably, the interior of the thermally insulating lower section is filled with thermal insulation material.

[0014] Preferably, the upper edge of the crucible is inclined inwardly by 1° to 15° to form a flow guide slope.

[0015] Preferably, it further comprises a thermal insulation material step, wherein the thermal insulation material step is arranged above the heater, and a quartz gas blocking ring is installed above the thermal insulation material step.

[0016] The method for reducing the oxygen content of a CZ single crystal comprises the following steps:

[0017] S10, charging: during charging, the quartz exhaust system as described in any one of the above systems for reducing the oxygen content of the CZ single crystal is closed, and only the graphite exhaust system at the bottom of the single crystal furnace is opened, so that most of the inert gas flows through and is distributed in the inner area of ​​the single crystal furnace;

[0018] S20, regulating the pressure in the single crystal furnace: after the material is oxidized, the quartz exhaust system and the graphite exhaust system are turned on at the same time, and when the pressure in the gas collecting chamber is controlled at a preset pressure, the position of the crucible is adjusted, and the gas path is blocked in cooperation with the thermal insulation material step and the quartz gas blocking ring. After the gas path is blocked, the gas in the single crystal furnace is mainly discharged by the quartz exhaust system until the process flow of preparing the entire single crystal is completed. By controlling the pressure in the gas collecting chamber at a preset pressure, the gas outflow speed can be effectively controlled, thereby controlling the volatilization rate of Oi. While exhausting through the quartz exhaust system, more volatile O elements can be taken away, preventing the O element from flowing into the solid-liquid interface front in the crucible, thereby reducing the O content.

[0019] Preferably, the preset pressure is 1 kPa to 50 kPa.

[0020] Preferably, the lower end of the gas collection chamber is 200 mm to 400 mm away from the melt surface in the crucible. When collecting gas, the flowing gas is cooled faster, so that the area above 800° C. of the crystal rod can be cooled at a faster rate.

[0021] The technical solution adopted in this application can achieve the following beneficial effects:

[0022] The present invention provides a system and method for reducing the oxygen content of a CZ single crystal. After the material is oxidized, most of the gas in the single crystal furnace is distributed to the gas collecting chamber through the gas inlet member. The gas in the gas collecting chamber can be discharged through the exhaust member. The pressure detection device detects the pressure in the gas collecting chamber through the quartz exhaust system, and controls the pressure in the gas collecting chamber within a range of 1 kPa to 50 kPa. The gas outflow speed in the single crystal furnace can be effectively controlled, thereby controlling the volatilization rate of Oi, increasing the exhaust capacity of the vacuum pump, taking away more volatile O elements, and preventing the O elements from flowing into the solid-liquid interface front, thereby finally reducing the O content and stably controlling the oxygen content in the single crystal silicon rod to be below 5 ppma.

[0023] While controlling the O content, the gas collection chamber can, through the flow of gas, take away the radiant heat absorbed by the surface of the upper part of the insulation component and the heat brought by the flow of fluid while collecting the gas, providing a better temperature field, thereby controlling the nucleation and growth of defects in the crystal rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the system structure for reducing the oxygen content of the CZ single crystal in the present application;

[0025] Figure 2 It is a schematic diagram of the structure of the quartz exhaust system in this application;

[0026] Figure 3 It is a line graph of the oxygen content of the single crystal rod in Example 1 and Comparative Example 2 of the present application.

[0027] In the figure: a single crystal furnace 100, an exhaust hole 110, a crucible 200, a heater 400, an insulating upper section 510, an insulating lower section 520, an air inlet member 610, a gas collecting chamber 620, an exhaust member 630, a thermal insulation material step 700, and a graphite exhaust system 800. DETAILED DESCRIPTION

[0028] In order to facilitate the understanding of the present application, the present application will be described more comprehensively below in conjunction with the accompanying drawings. And the preferred implementation of the present application is given. However, the present application can be implemented in many different forms and is not limited to the implementation described herein. On the contrary, the purpose of providing these implementations is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0030] For systems to reduce the oxygen content of CZ single crystals, please refer to Figures 1 to 3 , including a single crystal furnace 100 and a heater 400, and also including: a crucible 200, a heat insulation component, a quartz exhaust system, and a graphite exhaust system 800 arranged at the bottom of the single crystal furnace 100, wherein:

[0031] The heater 400 is disposed around the crucible 200 and is used to heat and melt the silicon material contained in the crucible 200;

[0032] The heat insulation component is located above the crucible 200 , and the heat insulation component includes a heat insulation upper section 510 and a heat insulation lower section 520 ;

[0033] The quartz exhaust system is arranged above the lower insulation section 520, and the quartz exhaust system includes an air inlet 610, an outer ring, an inner ring and at least one exhaust component 630. A gas collecting chamber 620 is formed between the outer ring and the inner ring. The air inlet 610 is connected to the gas collecting chamber 620 and the exhaust component 630. An exhaust hole 110 is opened on the single crystal furnace 100 corresponding to the exhaust component 630. The exhaust hole 110 is connected to a vacuum pump, and the exhaust component 630 is connected to the other end of the vacuum pump. A pressure detection device is provided at the exhaust hole 110, and the pressure detection device is used to detect the pressure in the gas collecting chamber 620.

[0034] In this embodiment, the graphite exhaust system 800 is arranged at the bottom of the single crystal furnace 100, so it can also be called a lower exhaust system. The size of the quartz exhaust system can be determined by those skilled in the art according to the size of the single crystal furnace 100 and actual conditions. The quartz exhaust system can also be called an upper exhaust system. The thermal insulation component can be a heat shield, a reflective shield, a spacer layer, etc., preferably a heat shield, which consists of two inner and outer cylindrical tubes, the outer tube is at the bottom, and the inner tube covers the outer tube; the quartz exhaust system is mainly used to discharge the gas in the single crystal furnace 100, the exhaust member 630 is an exhaust pipe, the exhaust pipe is perpendicular to the ring wall of the outer ring, the number of the exhaust pipes is preferably 4, and the positions corresponding to the exhaust pipes on the single crystal furnace 100 are respectively provided with 4 exhaust holes 110, and the pressure detection device is used to detect the pressure in the gas collection chamber 620, so that by controlling the pressure in the single crystal furnace 100 until it is stable, the gas outflow speed can be effectively controlled, thereby controlling the volatilization rate of Oi, increasing the exhaust capacity of the vacuum pump, and being able to take away more volatile O elements.

[0035] When in use, first, adjust the position of the crucible 200 so that the upper edge of the crucible 200 is flush with the upper edge of the heater 400, keep the gas path unobstructed, add silicon material into the crucible 200, open the graphite exhaust system 800 and the heater 400, and turn on the heater 400 to provide sufficient melting power to ensure that the silicon material in the crucible 200 is completely melted. At the same time, only turn on the graphite exhaust system 800 to ensure that most of the inert gas flows through and is distributed in the internal area of ​​the single crystal furnace 100. The graphite exhaust system 800 also includes a vacuum pump, which can complete the purge of the entire furnace and the thermal field system to remove residual impurities. After the melting is completed, turn on the quartz exhaust system and keep the graphite exhaust system on. The gas system 800 is turned on, and the gas in the single crystal furnace 100 first passes through the air inlet 610, and then is concentrated in the gas collecting chamber 620. The pressure detection device detects the gas in the gas collecting chamber 620, and controls the gas in the gas collecting chamber 620 to be within a range of 1 kPa to 50 kPa, and then is discharged to the outside of the single crystal furnace 100 through the exhaust component 630. When most of the gas in the single crystal furnace 100 is discharged, the crucible 200 and other corresponding components are adjusted so that the upper edge of the crucible 200 reaches the lowest height during the crystal growth process. At this time, the graphite exhaust system 800 is closed, and the quartz exhaust system is used as the main system. After the temperature and pressure in the furnace are stabilized, subsequent operations such as crystal induction and crystal growth are carried out.

[0036] During the crystal growth process, by setting the quartz exhaust system above the crucible 200 and controlling the pressure in the gas collecting chamber 620, more volatile O elements can be taken away while exhausting the gas in the single crystal furnace 100, preventing the O element from flowing into the solid-liquid interface front, and ultimately reducing the O content, effectively controlling O to below 5 ppm.

[0037] In order to optimize the gas flow path, in some specific embodiments, the gas inlet piece 610 is tilted inward along the cavity opening at one end of the gas collecting chamber 620, and a plurality of evenly distributed gas inlet holes are opened on the gas inlet piece 610. The tilt angle is 1° to 15°, and the diameter of the circular hole is 2 mm to 10 mm. The advantage of such a setting is that most of the gas in the single crystal furnace 100 can enter the gas collecting chamber 620 through the gas inlet holes in a short time.

[0038] The height between the outer ring and the inner ring is 300mm to 600mm, that is, the height of the gas collection chamber 620 is 300mm to 600mm. While collecting gas, the gas collection chamber 620 can take away the radiant heat absorbed by the upper surface of the insulation component and the heat brought by the fluid flow through the gas flow.

[0039] To ensure installation margin and ensure that there is no pressure contact between components under high-temperature thermal expansion conditions, in some preferred embodiments, the outer wall of the quartz exhaust system and the inner wall of the insulation component have a first gap, and the first gap is 1 mm to 20 mm.

[0040] In order to ensure that the temperature gradient of the crystal rod growth is within an appropriate range, further, the interior of the thermal insulation lower section 520 is filled with thermal insulation material.

[0041] In order to change the gas flow path and make the gas in the single crystal furnace 100 match the gas inlet portion, in some preferred embodiments, the upper edge of the crucible 200 is inclined inward by 1° to 15° to form a guide slope.

[0042] In some other preferred embodiments, a thermal insulation material step 700 is further included. The thermal insulation material step 700 is arranged above the heater 400. A quartz gas blocking ring is installed above the thermal insulation material step 700. The thermal insulation material step 700 reflects the heat of the heater 400 to ensure stable crystal growth power. A quartz gas blocking ring is installed above the thermal insulation material step 700 to block the air flow channel to reduce downwardly flowing gas and avoid affecting the heat transfer stability of the heater 400. It should be noted that the upper edge of the crucible 200 is always higher than the upper edge of the thermal insulation material step 700 during the crystal growth process.

[0043] The method for reducing the oxygen content of a CZ single crystal comprises the following steps:

[0044] S10, charging: during charging, the quartz exhaust system as described in any one of the above systems for reducing the oxygen content of the CZ single crystal is closed, and only the graphite exhaust system 800 located at the bottom of the single crystal furnace 100 is opened, so that most of the inert gas flows through and is distributed in the inner area of ​​the single crystal furnace 100;

[0045] S20, regulating the pressure in the single crystal furnace 100: after the material is oxidized, the quartz exhaust system and the graphite exhaust system 800 are turned on at the same time, and when the pressure in the gas collecting chamber 620 is controlled at a preset pressure, the position of the crucible 200 is adjusted, and the gas path is blocked in cooperation with the thermal insulation material step 700 and the quartz gas blocking ring. After the gas path is blocked, the gas in the single crystal furnace 100 is mainly discharged by the quartz exhaust system until the process flow of preparing the entire single crystal is completed. By controlling the pressure in the gas collecting chamber 620 at a preset pressure, the gas outflow speed can be effectively controlled, thereby controlling the volatilization rate of Oi. While exhausting through the quartz exhaust system, more volatile O elements can be taken away, preventing the O element from flowing into the solid-liquid interface front in the crucible 200, thereby reducing the O content.

[0046] The method provided by the present invention can be applied to the above-mentioned system for reducing the oxygen content of the CZ single crystal. Specifically, after the material is oxidized, the position of the crucible 200 is first adjusted to block the gas path of the graphite exhaust system 800, improve the gas flow area, and make the gas mainly discharged by the quartz exhaust system. Since the exhaust component 630 is connected to the vacuum pump, the gas in the single crystal furnace 100 can enter the gas inlet component 610, be distributed in the gas collection chamber 620, and be discharged through the exhaust component 630, and can take away the volatile O element when discharged.

[0047] It should be noted that the graphite exhaust system 800 does not assume the main exhaust function, but it still needs to be retained. During the crystal growth stage, pressure control is used to ensure that the lower half of the furnace chamber is in a near-vacuum state, which can improve the heating efficiency while reducing wall oxide accumulation and component oxidation and loss, thereby improving the thermal field without increasing service life.

[0048] In some preferred embodiments, the preset pressure is 1 kPa to 50 kPa. After the gas is collected by the gas collecting chamber 620, the gas is discharged through the exhaust pipe. The efficiency of the gas exhaust is measured by a pressure detection device and controlled by a vacuum pump to always ensure that the pressure in the single crystal furnace 100 is in a negative pressure state, that is, the vacuum pump exhaust effect controls the pressure in the gas collecting chamber 620 to be between 1 kPa and 50 kPa, which can effectively control the gas outflow speed, thereby controlling the volatilization rate of Oi, increasing the exhaust capacity of the vacuum pump, and being able to take away more volatile O elements, preventing the O element from flowing into the solid-liquid interface front, and ultimately reducing the O content, effectively controlling O to below 5 ppm.

[0049] Furthermore, the lower end of the gas collection chamber 620 is 200 mm to 400 mm away from the surface of the melt in the crucible 200. When collecting gas, the flowing gas is cooled down faster, so that the area above 800°C of the crystal rod can be cooled at a faster rate, which can suppress the nucleation rate and growth rate of single crystal defects, thereby providing single crystal products with better quality.

[0050] The following specific experimental examples are used to further illustrate the technical solutions and technical effects of the present invention. It should be noted that the following experimental examples are only for further explaining the present invention and do not limit the technical solutions of the present invention.

[0051] 1. Example 1

[0052] 1.1 Experimental equipment

[0053] The system for reducing the oxygen content of a Czochralski single crystal provided in the present application is used to prepare a single crystal rod.

[0054] 1.2 Experimental methods

[0055] This embodiment combines the system and method for reducing the oxygen content of Czochralski single crystals provided in this application to prepare a single crystal rod by the following steps:

[0056] Step 1: In the stage of material melting, first, the quartz exhaust system is closed, and the crucible 200 is moved down so that the upper edge of the crucible 200 is flush with the upper edge of the heater 400, the gas path is kept unobstructed, raw materials are added to the crucible 200, and the graphite exhaust system 800 and the lower heater 400 are opened. The lower heater 400 is turned on to provide sufficient material melting power to ensure that the silicon material in the crucible 200 is completely melted. When the silicon in the crucible 200 is completely melted, there is a large amount of gas in the single crystal furnace 100, and most of the gas flows through the internal area of ​​the single crystal furnace 100 through the graphite exhaust system 800, and the entire furnace and the thermal field system are purged to remove residual impurities (through the vacuum pump provided on the graphite exhaust system 800);

[0057] Step 2: Turn on the quartz exhaust system and keep the graphite exhaust system 800 turned on. Under the action of the vacuum pump, the gas generated in the crucible 200 enters the gas inlet 610 along the guide slope of the upper edge of the crucible 200, is distributed in the gas collecting chamber 620, and is discharged by the exhaust member 630. The pressure detection device detects the pressure in the gas collecting chamber 620. The pressure in the gas collecting chamber 620 is controlled at 25 kPa. By controlling the pressure in the gas collecting chamber 620, the pressure in the furnace can be kept stable. When the pressure in the furnace is stable, the crucible 200 and other corresponding components are moved upward. The upper edge of the crucible 200 reaches the lowest height in the above-mentioned crystal growth process. After the quartz gas blocking ring and the thermal insulation material step 700 block the gas path, the quartz exhaust system is used as the main exhaust. After stabilizing the pressure in the single crystal furnace 100, subsequent operations such as crystal induction and crystal growth are carried out to prepare a single crystal rod.

[0058] 1.3 Experimental Results

[0059] The single crystal rod prepared in Example 1 is tested for oxygen content by using an oxygen-carbon tester: the position of the single crystal rod is determined, and a single crystal silicon square is obtained after multiple cuttings. The single crystal silicon square is cleaned with deionized water or anhydrous ethanol, and then the single crystal silicon square is tested with an oxygen-carbon tester to obtain the oxygen content. The test results are as follows: Figure 3 As shown. Figure 3 It can be seen that the oxygen content of the single crystal rod prepared in this embodiment 1 is distributed in the range of O5 ppm to 5 ppm, which effectively illustrates that the quartz exhaust system can effectively control the gas outflow rate in the single crystal furnace 100, thereby controlling the volatilization rate of Oi, increasing the exhaust capacity of the vacuum pump, and being able to take away more volatile O elements, preventing O elements from flowing into the solid-liquid interface front, and ultimately reducing the O content;

[0060] In addition, while controlling the O content, the quartz exhaust component can provide a better temperature field, thereby controlling the nucleation and growth of defects in the crystal rod. The original thermal insulation material in the upper half of the insulation component replaces the external gas collection chamber 620. While collecting gas, the gas collection chamber 620 can carry away the radiant heat absorbed by the surface of the upper half of the insulation component and the heat brought by the flow of fluid through the gas flow.

[0061] The lower edge of the gas collection chamber 620 is 300 mm away from the melt surface. When collecting gas, the flowing gas is cooled down faster, so that the area above 800°C of the crystal rod can be cooled at a faster rate, thereby suppressing the nucleation rate and growth rate of single crystal defects, thereby providing single crystal products with better quality.

[0062] 2. Comparative Example 1

[0063] 2.1 Experimental equipment

[0064] The single crystal rod is prepared by using the system for preparing Czochralski single crystal in the prior art (only the graphite exhaust system 800).

[0065] 2.2 Experimental methods

[0066] The difference between this comparative example 1 and the above-mentioned embodiment 1 is that this comparative example 1 combines the system and method for preparing Czochralski single crystals in the prior art to prepare a single crystal rod, thereby preparing a single crystal rod.

[0067] 2.3 Experimental Results

[0068] The single crystal rod prepared in this comparative example 1 is tested for oxygen content by using an oxygen-carbon tester: the position of the single crystal rod is determined, and a single crystal silicon square is obtained after multiple cuttings. The single crystal silicon square is cleaned with deionized water or anhydrous ethanol, and then the single crystal silicon square is tested with an oxygen-carbon tester to obtain the oxygen content. The test results are as follows: Figure 3 As shown. Figure 3It can be seen that the oxygen content of the single crystal rod prepared in this comparative example 1 is distributed between 4.5 ppm and 7.1 ppm, and the oxygen content is significantly higher than the oxygen content of the crystal rod in Example 1.

[0069] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should be included in the protection scope of the present invention.

Claims

1. A system for reducing the oxygen content of a CZ single crystal, comprising a single crystal furnace and a heater, characterized in that: Also includes: The crucible, the heat insulation assembly, the quartz exhaust system arranged in the single crystal furnace, and the graphite exhaust system arranged at the bottom of the single crystal furnace: The heater is disposed around the crucible to heat and melt the silicon material contained in the crucible. The heat insulation component is located above the crucible, and the heat insulation component includes a heat insulation upper section and a heat insulation lower section; The quartz exhaust system is arranged above the lower insulation section, and the quartz exhaust system includes an air inlet, an outer ring, an inner ring and at least one exhaust member. A gas collecting chamber is formed between the outer ring and the inner ring. The air inlet is connected to the gas collecting chamber and the exhaust member. Exhaust holes are opened on the single crystal furnace corresponding to the exhaust member. The exhaust holes are connected to a vacuum pump, and the exhaust member is connected to the other end of the vacuum pump. A pressure detection device is arranged at the exhaust hole, and the pressure detection device is used to detect the pressure in the gas collecting chamber.

2. The system for reducing oxygen content of a CZ single crystal according to claim 1, characterized in that: The air inlet member is arranged inwardly along the cavity opening at one end of the gas collecting cavity, and a plurality of evenly distributed air inlet holes are opened on the air inlet member.

3. The system for reducing oxygen content in a CZ single crystal according to claim 1, characterized in that: The height between the outer ring and the inner ring is 300 mm to 600 mm.

4. The system for reducing oxygen content in a CZ single crystal according to claim 1, characterized in that: An outer wall of the quartz exhaust system and an inner wall of the thermal insulation component have a first gap, and the first gap is 1 mm to 20 mm.

5. The system for reducing oxygen content in a CZ single crystal according to claim 1, characterized in that: The interior of the heat-insulating lower section is filled with heat-insulating material.

6. The system for reducing oxygen content in a CZ single crystal according to claim 1, characterized in that: The upper edge of the crucible is inclined inwardly by 1° to 15° to form a flow guide slope.

7. The system for reducing oxygen content in a CZ single crystal according to claim 1, characterized in that: It also includes a thermal insulation material step, which is arranged above the heater, and a quartz gas blocking ring is installed above the thermal insulation material step.

8. A method for reducing the oxygen content of a CZ single crystal, characterized in that: The following steps are involved: S10, charging: during charging, the quartz exhaust system of the system for reducing the oxygen content of the CZ single crystal as described in any one of claims 1 to 7 is closed, and only the graphite exhaust system at the bottom of the single crystal furnace is opened, so that most of the inert gas flows through and is distributed in the inner area of ​​the single crystal furnace; S20, regulating the pressure in the single crystal furnace: after the material is oxidized, the quartz exhaust system and the graphite exhaust system are turned on at the same time, and when the pressure in the gas collecting chamber is controlled at a preset pressure, the position of the crucible is adjusted, and the gas path is blocked in cooperation with the thermal insulation material step and the quartz gas blocking ring. After the gas path is blocked, the gas in the single crystal furnace is mainly discharged by the quartz exhaust system until the process flow of preparing the entire single crystal is completed. By controlling the pressure in the gas collecting chamber at a preset pressure, the gas outflow speed can be effectively controlled, thereby controlling the volatilization rate of Oi. While exhausting through the quartz exhaust system, more volatile O elements can be taken away, preventing the O element from flowing into the solid-liquid interface front in the crucible, thereby reducing the O content.

9. The method for reducing the oxygen content of a CZ single crystal according to claim 8, characterized in that: The preset pressure is 1 kPa to 50 kPa.

10. The method for reducing the oxygen content of a CZ single crystal according to claim 8, characterized in that: The lower end of the gas collection chamber is 200 mm to 400 mm away from the melt surface in the crucible. When collecting gas, the flowing gas is cooled faster, so that the area above 800° C. of the crystal rod can be cooled at a faster rate.

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