A method for improving radial uniformity of germanium crystal

Abstract

The present application relates to the technical field of CZ monocrystal growth, and discloses a method for improving the radial uniformity of germanium crystal, which comprises the following steps: step one, preparation: polishing, etching, furnace loading and material melting; step two, crystal introduction; step three, necking; step four, shoulder setting; step five, equal-diameter; step six, finishing; and step seven, temperature reduction; the present application increases the high-temperature liquid flow of the solid-liquid interface moving from bottom to top by increasing the rotation of the crystal transfer pot, and increases the pulling speed, so that the solidification speed of the crystal is increased; since the latent heat of crystallization released on the solid-liquid interface is increased, the temperature of the melt near the crystal interface is increased, a part of the crystal at the melting interface is melted, and synchronous dynamic control makes the convex interface tend to be flat; the present application reduces the high-temperature liquid flow of the solid-liquid interface moving from bottom to top by reducing the rotation of the crystal transfer pot, and reduces the growth speed, so that the melt is solidified in a corresponding volume, and synchronous dynamic control makes the concave interface of the crystal tend to be flat.

Description

Technical Field

[0001] This invention relates to the field of CZ single crystal growth technology, specifically a method for improving the radial uniformity of germanium crystals. Background Technology

[0002] The basic principle of single crystal growth using the Czochralski method (hereinafter referred to as the CZ method) is to heat and melt the raw material for crystal growth in a crucible. A certain degree of supercooling is generated inside the melt, creating a nucleation driving force. A seed crystal, fixed at the lower end of a seed crystal rod, is immersed from the upper surface of the melt. After partial melting at the end of the seed crystal immersed in the melt, the seed crystal rod is pulled upwards at a certain speed. The heat generated at the solid-liquid interface during crystallization is transferred through the seed crystal rod. The melt in contact with the seed crystal first obtains a certain degree of supercooling and begins the crystallization process. As the seed crystal rod is slowly pulled up, continuous crystal growth can be achieved by controlling factors such as temperature and pulling speed. The CZ method allows for real-time observation of the crystal growth dynamics, making it easy to monitor the crystal growth. The growth conditions are easy to control. Moreover, during the crystal growth process, the crystal does not contact the crucible wall, which can significantly reduce parasitic nucleation generated between the crystal and the crucible wall. In addition, crystals grown by the Czochralski method have high integrity, fast growth rate, and large crystal size. Crystals with specific crystal orientations can be grown according to the crystal orientation of the seed crystal. Therefore, it is widely used in the field of single crystal growth.

[0003] During the growth of germanium crystals, the flatness of the solid-liquid interface is affected by heat exchange, including the latent heat of phase transition released by the solidification of molten germanium, the thermal conduction of the melt, the upward thermal conduction through the crystal, and the outward radiative heat through the crystal. At the head of the growing crystal, heat is transferred through the seed crystal rod, and the temperature gradient inside the crystal is large, making the longitudinal thermal conduction of the crystal greater than the surface radiative heat. Therefore, the solid-liquid interface is convex to the melt. When the crystal grows to the middle, the longitudinal thermal conduction equals the surface radiative heat, so the interface is flat. At the tail of the crystal, the longitudinal thermal conduction is less than the surface radiative heat, so the solid-liquid interface is concave to the melt.

[0004] The flatness of the solid-liquid interface of a crystal directly affects its radial uniformity, and excellent crystal performance largely depends on good radial uniformity. For example, the uniformity can be calculated using the following formula: RD=2((n2-n1) / (n2+n1)). High-purity germanium crystals require a radial carrier concentration uniformity of 5%-15%, which places extremely stringent requirements on crystal growth control. Summary of the Invention

[0005] The purpose of this invention is to provide a method for improving the radial uniformity of germanium crystals, so as to solve the problems mentioned in the background art. Technical solution

[0006] This invention provides the following technical solution: a method for improving the radial uniformity of germanium crystals, comprising the following steps: Step 1: Preparation Raw material polishing: Remove rough edges and burrs from the raw material surface until smooth, then rinse thoroughly with pure water; Corrosion: Immerse in the corrosion solution until the surface of the germanium material is shiny, remove it, rinse with pure water, and dry the germanium material with high-purity nitrogen gas; Loading the furnace: Fix the germanium material to the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible, then seal the pulling furnace; Chemical melting: Turn on the crystal turner and crucible turner, and control the temperature inside the furnace to completely melt the germanium material; Step 2, crystal introduction: Slowly insert the seed crystal into the melt, adjust the induction heating power in the furnace according to the melt interface, wait until a certain width of aperture appears, and then start crystal introduction; Step 3, necking: Manually increase and control the induction heating power to stabilize the crystal diameter within the standard diameter range; Step 4, Shoulder Formation: Control the induction heating power to cool down evenly, and stop cooling after the crystal diameter gradually increases; Step 5, Equal Diameter: Observe the crystal diameter and manually control the induction heating power; Step Six, Finishing: Control the induction heating power to raise the temperature evenly until all the molten liquid in the quartz crucible is completely drawn out; Step 7, Cooling: Turn off the crystal riser, control the power to cool down to room temperature, turn off the crystal rotation and crucible rotation, and complete the crystal pulling.

[0007] Preferably, in the material processing step of step one, the crystal rotation speed and the crucible rotation speed are the same.

[0008] Preferably, in step two, when starting crystal pulling, the pulling speed is gradually increased and maintained at this pulling speed to control the crystal diameter to be stable.

[0009] Preferably, from step four to the first half of step five, the crystal rotation and crucible rotation are manually increased in a decreasing manner every 30 minutes, and then the crystal rotation and crucible rotation are kept constant thereafter.

[0010] Preferably, from step four to the first half of step five, the pulling speed is manually increased in a decreasing manner every 30 minutes, and then the pulling speed is kept constant thereafter.

[0011] Preferably, from the second half of step five to the completion of step six, the crystal rotation and crucible rotation are manually and incrementally reduced every 30 minutes, and then the crystal rotation and crucible rotation are kept constant thereafter.

[0012] Preferably, from the second half of step five to the completion of step six, the pulling speed is manually and incrementally reduced every 30 minutes, and then the pulling speed is kept constant thereafter.

[0013] Beneficial effects

[0014] Compared with the prior art, the present invention provides a method for improving the radial uniformity of germanium crystals, which has the following beneficial effects: 1. In the part of crystal growth, from the beginning of shoulder formation to the first half of the constant diameter section, the crystal rotation and crucible rotation are manually increased in a decreasing manner every 30 minutes. The increase values ​​are 1.0 r / min, 0.8 r / min, 0.6 r / min, 0.4 r / min and 0.2 r / min respectively. The crystal rotation and crucible rotation are kept constant thereafter.

[0015] From the beginning of shoulder relaxation to the first half of the equal diameter section, manually increase the pulling speed gradually every 30 minutes, with the increase values ​​being 5mm / h, 4mm / h, 3mm / h, 2mm / h, and 1mm / h respectively, and then keep the pulling speed constant thereafter.

[0016] Increasing the rotation of the crystal transfer crucible increases the high-temperature liquid flow moving upwards at the solid-liquid interface, making the convex interface tend to be flatter; increasing the pulling speed increases the crystal solidification rate, and due to the increase in the latent heat of crystallization released at the solid-liquid interface, the temperature of the melt near the interface rises, resulting in the melting of a portion of the crystals at the interface, making the interface tend to be flatter.

[0017] 2. In the later part of crystal growth, from the second half of the constant diameter section to the end, the crystal rotation and crucible rotation are manually and incrementally reduced every 30 minutes. The reduction values ​​are 0.2 r / min, 0.4 r / min, 0.6 r / min, 0.8 r / min and 1.0 r / min respectively. The crystal rotation and crucible rotation are then kept constant.

[0018] From the second half of the equal diameter section to the end, manually decrease the pulling speed every 30 minutes, with the decrease values ​​being 1mm / h, 2mm / h, 3mm / h, 4mm / h, and 5mm / h respectively, and then keep the pulling speed constant thereafter.

[0019] Reducing the rotation of the crystal transfer vessel decreases the high-temperature liquid flow moving upwards at the solid-liquid interface, making the concave interface more flat; reducing the growth rate causes the melt to solidify to a corresponding volume, making the growth interface more flat.

[0020] It should be understood that the foregoing general description and the following detailed description are exemplary and illustrative only, and are not intended to limit this disclosure.

[0021] This application provides an overview of various implementations or examples of the technology described in this disclosure, and is not a full disclosure of the entire scope or all features of the disclosed technology. Detailed Implementation

[0022] The embodiments of the invention provide a clear and complete description of the technical solutions of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention provides a technical solution: a method for improving the radial uniformity of germanium crystals, illustrated by taking a 3-inch diameter germanium single crystal as an example. Example 1

[0024] Step 1: Preparation A. Raw material polishing: Prepare 7 kg of germanium ingot raw material with a carrier concentration ≤ 8.0E+10 / cm³, polish it with a scouring pad to remove the roughness and burrs on the surface of the raw material until the surface is smooth, and rinse it with pure water. B. Corrosion: Place the germanium material in a corrosive liquid of HNO3:HF = 2.5:1 and corrode until the surface is shiny. Remove it, rinse with pure water for 1 hour, and dry the germanium material with high-purity nitrogen. C. Loading the furnace: Prepare a high-purity seed crystal, fix it in the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible. Seal the pulling furnace, evacuate to below 1 Pa, and then purge with high-purity hydrogen for 4 hours. D. Melting: Start the crystal rotation at 3r / min, start the crucible rotation at 3r / min, control the power to raise the temperature to 1000℃ within 3.5h, keep the temperature constant, wait for the germanium material to completely melt, then cool down to 970℃ and keep the temperature constant for 40min. Step 2, crystal pulling: Slowly insert the seed crystal into the melt, adjust the power according to the melt interface, and wait 15 minutes after a certain width of aperture appears before starting crystal pulling: Gradually increase the pulling speed to 25mm / h, maintain this pulling speed for 20 minutes, and control the crystal diameter to be stable at 7mm as the standard. Step 3, necking: Manually increase and control the power to stabilize the crystal diameter at 3.5mm, and pull out a 120mm long neck.

[0025] Step 4, Shoulder Formation: Control the power to cool down evenly at a frequency of 150W / h, allowing the shoulder to form for 1.5 hours. The crystal diameter will gradually grow to 78mm, at which point cooling will be stopped. Step 5, equal diameter: Observe the crystal diameter and manually control the power to keep the crystal diameter at 82mm. The equal diameter process takes 5 hours. From the beginning of the shoulder formation to the first half of the constant diameter section, the crystal rotation and crucible rotation were manually increased in a decreasing manner every 30 minutes, with the increases being 1.0 r / min, 0.8 r / min, 0.6 r / min, 0.4 r / min, and 0.2 r / min respectively. Subsequently, the crystal rotation and crucible rotation were kept constant.

[0026] From the beginning of shoulder relaxation to the first half of the equal diameter section, manually increase the pulling speed gradually every 30 minutes, with the increase values ​​being 5mm / h, 4mm / h, 3mm / h, 2mm / h, and 1mm / h respectively, and then keep the pulling speed constant thereafter.

[0027] Step 6, Finishing: When there is 1.5kg of raw material left in the crucible, control the power to heat up evenly at a frequency of 150w / h, and finish for 1.5h until all the melt in the quartz crucible is completely drawn out. From the second half of the constant diameter section to the end, the crystal rotation and crucible rotation were manually and incrementally reduced every 30 minutes, with reduction values ​​of 0.2 r / min, 0.4 r / min, 0.6 r / min, 0.8 r / min, and 1.0 r / min respectively. The crystal rotation and crucible rotation were then kept constant.

[0028] From the second half of the equal diameter section to the end, manually decrease the pulling speed every 30 minutes, with the decrease values ​​being 1mm / h, 2mm / h, 3mm / h, 4mm / h, and 5mm / h respectively, and then keep the pulling speed constant thereafter.

[0029] Step 7, Cooling: Turn off crystal lifting and control the power to cool down to room temperature. Cooling is divided into three stages: Stage 1: 350W / h, cooling for 1 hour; Stage 2: 550W / h, cooling for 2 hours; Stage 3: 900W / h, cooling for 6 hours, until room temperature is reached. Then turn off crystal rotation and crucible rotation to complete crystal pulling.

[0030] Comparative Example 1: Step 1: Preparation A. Raw material polishing: Prepare 7 kg of germanium ingot raw material with a carrier concentration ≤ 8.0E+10 / cm³, polish it with a scouring pad to remove the roughness and burrs on the surface of the raw material until the surface is smooth, and rinse it with pure water. B. Corrosion: Place the germanium material in a corrosive liquid of HNO3:HF = 2.5:1 and corrode until the surface is shiny. Remove it, rinse with pure water for 1 hour, and dry the germanium material with high-purity nitrogen. C. Loading the furnace: Prepare a high-purity seed crystal, fix it in the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible. Seal the pulling furnace, evacuate to below 1 Pa, and then purge with high-purity hydrogen for 4 hours. D. Melting: Start the crystal rotation at 3r / min, start the crucible rotation at 3r / min, control the power to raise the temperature to 1000℃ within 3.5h, keep the temperature constant, wait for the germanium material to completely melt, then cool down to 970℃ and keep the temperature constant for 40min. Step 2, crystal pulling: Slowly insert the seed crystal into the melt, adjust the power according to the melt interface, and wait 15 minutes after a certain width of aperture appears before starting crystal pulling: pull speed 25mm / h, maintain this pulling speed for 20 minutes, and control the crystal diameter to be stable at 7mm as the standard. Step 3, necking: Manually increase and control the power to stabilize the crystal diameter at 3.5mm, and pull out a 120mm long neck.

[0031] Step 4, Shoulder Formation: Control the power to cool down evenly at a frequency of 150W / h, allowing the shoulder to form for 1.5 hours. The crystal diameter will gradually grow to 78mm, at which point cooling will be stopped. Step 5, equal diameter: Observe the crystal diameter and manually control the power to keep the crystal diameter at 82mm. The equal diameter process takes 5 hours. From the beginning of the shoulder formation to the first half of the constant diameter section, the crystal rotation and crucible rotation are kept constant.

[0032] From the beginning of the shoulder release to the first half of the equal diameter section, maintain a constant pulling speed.

[0033] Step 6, Finishing: When there is 1.5kg of raw material left in the crucible, control the power to heat up evenly at a frequency of 150w / h, and finish for 1.5h until all the molten liquid in the quartz crucible is completely drawn out. From the second half of the equal diameter section to the end, the crystal rotation and crucible rotation are kept constant.

[0034] From the second half of the equal diameter section to the end, maintain a constant pulling speed.

[0035] Step 7, Cooling: Turn off crystal lifting and control the power to cool down to room temperature. Cooling is divided into three stages: Stage 1: 350W / h, cooling for 1 hour; Stage 2: 550W / h, cooling for 2 hours; Stage 3: 900W / h, cooling for 6 hours, until room temperature is reached. Then turn off crystal rotation and crucible rotation to complete crystal pulling.

[0036] Comparative Example 2: Step 1: Preparation A. Raw material polishing: Prepare 7 kg of germanium ingot raw material with a carrier concentration ≤ 8.0E+10 / cm³, polish it with a scouring pad to remove the roughness and burrs on the surface of the raw material until the surface is smooth, and rinse it with pure water. B. Corrosion: Place the germanium material in a corrosive liquid of HNO3:HF = 2.5:1 and corrode until the surface is shiny. Remove it, rinse with pure water for 1 hour, and dry the germanium material with high-purity nitrogen. C. Loading the furnace: Prepare a high-purity seed crystal, fix it in the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible. Seal the pulling furnace, evacuate to below 1 Pa, and then purge with high-purity hydrogen for 4 hours. D. Melting: Start the crystal rotation at 3r / min, start the crucible rotation at 3r / min, control the power to raise the temperature to 1000℃ within 3.5h, keep the temperature constant, wait for the germanium material to completely melt, then cool down to 970℃ and keep the temperature constant for 40min. Step 2, crystal pulling: Slowly insert the seed crystal into the melt, adjust the power according to the melt interface, and wait 15 minutes after a certain width of aperture appears before starting crystal pulling: Gradually increase the pulling speed to 25mm / h, maintain this pulling speed for 20 minutes, and control the crystal diameter to be stable at 7mm as the standard. Step 3, necking: Manually increase and control the power to stabilize the crystal diameter at 3.5mm, and pull out a 120mm long neck.

[0037] Step 4, Shoulder Formation: Control the power to cool down evenly at a frequency of 150W / h, allowing the shoulder to form for 1.5 hours. The crystal diameter will gradually grow to 78mm, at which point cooling will be stopped. Step 5, equal diameter: Observe the crystal diameter and manually control the power to keep the crystal diameter at 82mm. The equal diameter process takes 5 hours. From the beginning of the shoulder formation to the first half of the constant diameter section, the crystal rotation and crucible rotation are constant.

[0038] From the beginning of shoulder relaxation to the first half of the equal diameter section, manually increase the pulling speed gradually every 30 minutes, with the increase values ​​being 5mm / h, 4mm / h, 3mm / h, 2mm / h, and 1mm / h respectively, and then keep the pulling speed constant thereafter.

[0039] Step 6, Finishing: When there is 1.5kg of raw material left in the crucible, control the power to heat up evenly at a frequency of 150w / h, and finish for 1.5h until all the molten liquid in the quartz crucible is completely drawn out. From the second half of the equal diameter section to the end, the crystal rotation and crucible rotation are kept constant.

[0040] From the second half of the equal diameter section to the end, manually decrease the pulling speed every 30 minutes, with the decrease values ​​being 1mm / h, 2mm / h, 3mm / h, 4mm / h, and 5mm / h respectively, and then keep the pulling speed constant thereafter.

[0041] Step 7, Cooling: Turn off crystal lifting and control the power to cool down to room temperature. Cooling is divided into three stages: Stage 1: 350W / h, cooling for 1 hour; Stage 2: 550W / h, cooling for 2 hours; Stage 3: 900W / h, cooling for 6 hours, until room temperature is reached. Then turn off crystal rotation and crucible rotation to complete crystal pulling.

[0042] Comparative Example 3: Step 1: Preparation A. Raw material polishing: Prepare 7 kg of germanium ingot raw material with a carrier concentration ≤ 8.0E+10 / cm³, polish it with a scouring pad to remove the roughness and burrs on the surface of the raw material until the surface is smooth, and rinse it with pure water. B. Corrosion: Place the germanium material in a corrosive liquid of HNO3:HF = 2.5:1 and corrode until the surface is shiny. Remove it, rinse with pure water for 1 hour, and dry the germanium material with high-purity nitrogen. C. Loading the furnace: Prepare a high-purity seed crystal, fix it in the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible. Seal the pulling furnace, evacuate to below 1 Pa, and then purge with high-purity hydrogen for 4 hours. D. Melting: Start the crystal rotation at 3r / min, start the crucible rotation at 3r / min, control the power to raise the temperature to 1000℃ within 3.5h, keep the temperature constant, wait for the germanium material to completely melt, then cool down to 970℃ and keep the temperature constant for 40min. Step 2, crystal pulling: Slowly insert the seed crystal into the melt, adjust the power according to the melt interface, and wait 15 minutes after a certain width of aperture appears before starting crystal pulling: pull speed 25mm / h, maintain this pulling speed for 20 minutes, and control the crystal diameter to be stable at 7mm as the standard. Step 3, necking: Manually increase and control the power to stabilize the crystal diameter at 3.5mm, and pull out a 120mm long neck.

[0043] Step 4, Shoulder Formation: Control the power to cool down evenly at a frequency of 150W / h, allowing the shoulder to form for 1.5 hours. The crystal diameter will gradually grow to 78mm, at which point cooling will be stopped. Step 5, equal diameter: Observe the crystal diameter and manually control the power to keep the crystal diameter at 82mm. The equal diameter process takes 5 hours. From the beginning of the shoulder formation to the first half of the constant diameter section, the crystal rotation and crucible rotation were manually increased in a decreasing manner every 30 minutes, with the increases being 1.0 r / min, 0.8 r / min, 0.6 r / min, 0.4 r / min, and 0.2 r / min respectively. Subsequently, the crystal rotation and crucible rotation were kept constant.

[0044] From the beginning of the shoulder release to the first half of the equal diameter section, maintain a constant pulling speed.

[0045] Step 6, Finishing: When there is 1.5kg of raw material left in the crucible, control the power to heat up evenly at a frequency of 150w / h, and finish for 1.5h until all the molten liquid in the quartz crucible is completely drawn out. From the second half of the constant diameter section to the end, the crystal rotation and crucible rotation were manually and incrementally reduced every 30 minutes, with reduction values ​​of 0.2 r / min, 0.4 r / min, 0.6 r / min, 0.8 r / min, and 1.0 r / min respectively. The crystal rotation and crucible rotation were then kept constant.

[0046] From the second half of the equal diameter section to the end, maintain a constant pulling speed.

[0047] Step 7, Cooling: Turn off crystal lifting and control the power to cool down to room temperature. Cooling is divided into three stages: Stage 1: 350W / h, cooling for 1 hour; Stage 2: 550W / h, cooling for 2 hours; Stage 3: 900W / h, cooling for 6 hours, until room temperature is reached. Then turn off crystal rotation and crucible rotation to complete crystal pulling.

[0048] In Comparative Example 1, except for the crystal rotation speed of 3r / min, the crucible rotation speed of 3r / min, and the pulling speed of 25mm / h throughout the process, all other processes and conditions were completely the same as those in Example 1 for growing germanium single crystals, that is, the crystal rotation, crucible rotation and pulling speed conditions were not changed. In Comparative Example 2, except for the crystal rotation speed of 3r / min throughout the process and the crucible rotation speed of 3r / min after opening, all other processes and conditions were exactly the same as those in Example 1 for growing germanium single crystals, that is, only the pulling speed was changed. In Comparative Example 3, except that the pulling speed was 25 mm / h throughout the process, all other processes and conditions were exactly the same as those in the Example to grow the single crystal, that is, only the crystal rotation and crucible rotation conditions were changed.

[0049] Hall plates and dislocation plates were taken from the same positions at the middle section of the shoulder, the middle section of the constant diameter, and the middle section of the tail section of the germanium crystals produced in Example 1 and the three comparative examples, respectively, and the radial uniformity was calculated. The test results are recorded in the table below:

[0050] As can be seen from the table above, the method for improving the radial uniformity of germanium crystals provided by this invention improves the solid-liquid interface of the germanium crystal by dynamically controlling the pulling speed, crucible rotation, and crystal rotation from the beginning of the shoulder formation to the first half of the equal diameter stage, making the convex interface tend to be flat; and by dynamically controlling the pulling speed, crucible rotation, and crystal rotation from the second half of the equal diameter stage to the end, it improves the solid-liquid interface of the germanium crystal, making the concave interface tend to be flat, thereby greatly improving the radial uniformity of the crystal. It can also be seen that this method of dynamically controlling the pulling speed, crucible rotation, and crystal rotation has no impact on the purity of the crystal, defects (dislocations), etc.

[0051] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above description is illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A method for improving the radial uniformity of germanium crystals, characterized in that: Includes the following steps: Step 1: Preparation Raw material polishing: Remove rough edges and burrs from the raw material surface until smooth, then rinse thoroughly with pure water; Corrosion: Immerse in the corrosion solution until the surface of the germanium material is shiny, remove it, rinse with pure water, and dry the germanium material with high-purity nitrogen gas; Loading the furnace: Fix the germanium material to the seed crystal chuck below the seed crystal rod, and knock the germanium material into small pieces and load it into the quartz crucible, then seal the pulling furnace; Chemical melting: Turn on the crystal turner and crucible turner, and control the temperature inside the furnace to completely melt the germanium material; Step 2, crystal introduction: Slowly insert the seed crystal into the melt, adjust the induction heating power in the furnace according to the melt interface, wait until a certain width of aperture appears, and then start crystal introduction; Step 3, necking: Manually increase and control the induction heating power to stabilize the crystal diameter within the standard diameter range; Step 4, Shoulder Formation: Control the induction heating power to cool down evenly, and stop cooling after the crystal diameter gradually increases; Step 5, Equal Diameter: Observe the crystal diameter and manually control the induction heating power; Step Six, Finishing: Control the induction heating power to raise the temperature evenly until all the molten liquid in the quartz crucible is completely drawn out; Step 7, Cooling: Turn off the crystal riser, control the power to cool down to room temperature, turn off the crystal rotation and crucible rotation, and complete the crystal pulling.

2. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: In the material processing step of step one, the crystal rotation speed is the same as the crucible rotation speed.

3. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: In step two, when starting to pull the crystal, the pulling speed is gradually increased and maintained at this pulling speed to control the crystal diameter to be stable.

4. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: From step four to the first half of step five, the crystal rotation and crucible rotation are manually increased in a decreasing manner every 30 minutes, and then the crystal rotation and crucible rotation are kept constant thereafter.

5. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: From step four to the first half of step five, the pulling speed is manually increased in a decreasing manner every 30 minutes, and then the pulling speed is kept constant thereafter.

6. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: From the latter half of step five to the completion of step six, the crystal rotation and crucible rotation are manually and incrementally reduced every 30 minutes, and then the crystal rotation and crucible rotation are kept constant thereafter.

7. The method for improving the radial uniformity of germanium crystals according to claim 1, characterized in that: From the latter half of step five to the completion of step six, the pulling speed is manually and incrementally reduced every 30 minutes, and then the pulling speed is kept constant thereafter.

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