Method for adjusting wide surface of 111 czochralski silicon rod and product thereof
By using partial crystal seed crystal and inert gas protection technology, the wide surface formation of single crystal silicon rods is optimized, which solves the problem of inaccurate wide surface control in the prior art, and improves the yield and material utilization.
Patent Information
- Application Number
- CN202510349896.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-24
- Publication Date
- 2025-06-06
AI Technical Summary
In the prior art, when using straight-pull method to grow single crystal silicon rods, the process parameters are empirically adjusted to control the wide surface on the single crystal silicon rods is not accurate enough, resulting in a low yield.
The semicrystalline seed crystal is adopted, and its crystallographic orientation has an angle deviation of 1° to 1.5° from the target crystal direction 111, and the raw materials are heated and melted under the protection of inert gas, and the rotation speed and pulling speed of the semicrystalline seed crystal are controlled to optimize the wide surface formation of the single crystal silicon rod.
Through this method, the wide surface size of the single crystal silicon rod can be accurately controlled, the production yield can be improved, material waste can be reduced, and the utilization and production efficiency of single crystal silicon materials can be improved.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of semiconductor technology, and in particular relates to a method for adjusting the width of a 111 Czochralski single crystal silicon rod and a product thereof. Background Art
[0002] Single crystal silicon is one of the most important basic materials in the semiconductor industry and is widely used in integrated circuits, solar cells, optoelectronic devices and other fields. The Czochralski method (CZ method) is currently one of the main methods for preparing single crystal silicon. However, in the process of using the Czochralski method (CZ method) to pull 111 single crystal silicon rods, a wide surface that is naturally formed during the crystal growth process will be produced. The formation of this wide surface has a specific crystallographic reason: when the Czochralski single crystal silicon rod is pulled along <111> When the crystal grows in the direction of rotation, its crystal structure shows three symmetrical {111} crystal planes at the microscopic level. These crystal planes will naturally appear during the growth process and appear in a triangular or hexagonal shape in the cross section. The more prominent {111} crystal plane part appears as the wide face on the crystal rod at the macroscopic level.
[0003] The width of the wide face is a key indicator to measure the size of the wide face. If the wide face is too large, it will increase the difficulty of the subsequent rolling process. That is, after rolling to the specified size (such as 8 inches), there is still a wide face or old skin on the surface of the crystal rod, then the section of the crystal ingot cannot be used, resulting in yield loss and material waste; if the wide face is too small, it will increase the difficulty of judging the state of the crystal during the crystal pulling process. That is, when the 111 crystal rod NG changes from single crystal to polycrystalline, the crystal line and wide face will have broken edges and cross-sections. This phenomenon is helpful to determine whether the crystal is NG on site. However, when the wide face is too small, it will be not conducive to the actual operation in production, and misjudgment will also cause yield loss and material waste.
[0004] At present, when growing (111) oriented single crystal silicon rods by the traditional Czochralski method, the control of the width mainly relies on the experience-based adjustment of process parameters (such as pulling speed, rotation speed, temperature gradient, etc.). However, this method is difficult to accurately control the size of the width and is easily affected by external factors, resulting in large fluctuations in the width, which affects the production yield. Summary of the invention
[0005] In view of this, the present invention provides a method for adjusting the width of a 111 Czochralski single crystal silicon rod and a product thereof, so as to solve the technical problem in the prior art that when growing single crystal silicon rods by the Czochralski method, the process parameters are adjusted empirically to control the width of the single crystal silicon rod in an inaccurate manner, resulting in a low production yield.
[0006] To achieve the above objectives, this application adopts the following scheme: A method for adjusting the width of a 111 CZ silicon rod comprises the following steps: S10: selecting a eutectic seed crystal, whose crystallographic orientation has an angle deviation of 1° to 1.5° from the target crystal direction 111, and polishing its surface to ensure that it is free of damage and contamination; S20: selecting raw materials, placing them in a quartz crucible, and heating them under the protection of an inert gas to completely melt them to obtain a melt; S30: slowly lowering the eccentric seed crystal to the surface of the melt to make the eccentric seed crystal start to grow, controlling the rotation speed of the eccentric seed crystal to 10 rpm to 15 rpm, and the pulling speed to 0.8 mm / min to 1 mm / min, to obtain a single crystal silicon rod.
[0007] Preferably, in S10 , a unimorphic seed crystal is selected, and its crystallographic orientation has an angular deviation of 1.5° from the target crystal direction 111 .
[0008] Preferably, in S10, the diameter of the eutectic seed crystal is 5 mm to 10 mm.
[0009] Preferably, in S20, high-purity polysilicon is used as a raw material, and an appropriate amount of dopant is added to the raw material to meet the electrical performance requirements of the final product.
[0010] Preferably, in S20, the flow rate of the inert gas is 50 slm to 100 slm.
[0011] Preferably, in S30, the crucible rotation speed is 5 rpm to 10 rpm.
[0012] Preferably, in S30, the furnace pressure is 5 KPa to 10 KPa.
[0013] Preferably, in S30, the diameter of the single crystal silicon rod drawn is 150 mm to 250 mm.
[0014] The single crystal silicon rod product is prepared according to the above method of adjusting the wide surface of the 111 Czochralski single crystal silicon rod.
[0015] In the above method for adjusting the wide face of the 111 Czochralski single crystal silicon rod, first, a unimorphic seed crystal with an angle deviation of 1° to 1.5° is selected, and the surface of the unimorphic seed crystal is polished to ensure that it is free of damage and pollution, which helps to reduce defects and impurities on the surface of the seed crystal, thereby reducing the risk of introducing new defects during the growth process. Then, the raw materials are heated and melted under the protection of an inert gas, which can effectively prevent oxidation and contamination of silicon and ensure the purity of the melt. Subsequently, the unimorphic seed crystal is slowly lowered to the surface of the melt to allow the unimorphic seed crystal to begin to grow. During the growth process, the unimorphic seed crystal can guide the single crystal silicon rod to grow along a specific direction (close to but not completely equal to the 111 crystal direction), thereby optimizing the formation of the wide face. This micro- Small angular deviation helps to reduce thermal stress and dislocation during the growth process, making the wide surface smoother and more uniform. The crystal rod grown from the eccentric seed crystal with an angular deviation of 1° to 1.5° has an appropriate wide surface size, with an average wide surface width of 4.2 cm. The average yield of the crystal rod with this wide surface size in subsequent processing is 78.45%. A higher yield can improve the utilization rate and production efficiency of single crystal silicon materials and reduce production costs. Controlling the rotation speed and pulling speed of the eccentric seed crystal within a specific range (10rpm to 15rpm and 0.8mm / min to 1mm / min) during crystal pulling helps to maintain stable growth conditions, reduce fluctuations and defects in the growth process, and thus improve the overall quality of the crystal. DETAILED DESCRIPTION
[0016] In order to facilitate the understanding of the present application, the present application will be described in more detail below. And the preferred embodiments of the present application are given. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly understood.
[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly 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 of the related listed items.
[0018] This embodiment provides a method for adjusting the width of a 111 Czochralski single crystal silicon rod, comprising the following steps: S10: selecting a eutectic seed crystal, whose crystallographic orientation has an angle deviation of 1° to 1.5° from the target crystal direction 111, and polishing its surface to ensure that it is free of damage and contamination; S20: selecting raw materials, placing them in a quartz crucible, and heating them under the protection of an inert gas to completely melt them to obtain a melt; S30: slowly lowering the eccentric seed crystal to the surface of the melt to make the eccentric seed crystal start to grow, controlling the rotation speed of the eccentric seed crystal to 10 rpm to 15 rpm, and the pulling speed to 0.8 mm / min to 1 mm / min, to obtain a single crystal silicon rod.
[0019] During operation, first select an eccentric seed crystal whose crystallographic orientation has an angle deviation of 1° to 1.5° from the target crystal orientation 111. The eccentric seed crystal helps to adjust the wide surface of the single crystal silicon rod through a slight crystal orientation deviation during the subsequent crystal growth process, and polish the surface of the eccentric seed crystal to ensure that the surface of the seed crystal is undamaged and uncontaminated. Polishing can improve the purity of the seed crystal, reduce metal contamination caused by the seed crystal, and ensure good contact between the seed crystal and the molten silicon; then, select high-purity polycrystalline silicon raw material and put it into a quartz crucible. The quartz crucible has high temperature stability and chemical inertness, and is an ideal container for growing single crystal silicon by the Czochralski method. It is heated under the protection of an inert gas (such as argon) to completely melt the polycrystalline silicon raw material to obtain a melt. The use of an inert gas can isolate the air, prevent the melt from being oxidized, and improve the quality of the melt; then, slowly lower the treated eccentric seed crystal to the surface of the melt. The surface is formed so that the seed crystal contacts the molten silicon and starts to grow. During the growth process, the rotation speed and pulling speed of the seed crystal need to be controlled. The rotation speed is controlled between 10rpm and 15rpm, which helps to make the heat and material distribution in the melt more uniform and reduce thermal stress and dislocation during crystal growth. The pulling speed is controlled between 0.8mm / min and 1mm / min to ensure that the crystal grows at a stable rate while ensuring the quality and uniformity of the crystal. Finally, shoulder release, equal diameter and other steps are performed according to the process steps in the prior art to prepare a single crystal silicon rod.
[0020] In the above method for adjusting the wide face of the 111 Czochralski single crystal silicon rod, first, a unimorphic seed crystal with an angle deviation of 1° to 1.5° is selected, and the surface of the unimorphic seed crystal is polished to ensure that it is free of damage and pollution, which helps to reduce defects and impurities on the surface of the seed crystal, thereby reducing the risk of introducing new defects during the growth process. Then, the raw materials are heated and melted under the protection of an inert gas, which can effectively prevent oxidation and contamination of silicon and ensure the purity of the melt. Subsequently, the unimorphic seed crystal is slowly lowered to the surface of the melt to allow the unimorphic seed crystal to begin to grow. During the growth process, the unimorphic seed crystal can guide the single crystal silicon rod to grow along a specific direction (close to but not completely equal to the 111 crystal direction), thereby optimizing the formation of the wide face. This micro- Small angular deviation helps to reduce thermal stress and dislocation during the growth process, making the wide surface smoother and more uniform. The crystal rod grown from the eccentric seed crystal with an angular deviation of 1° to 1.5° has an appropriate wide surface size, with an average wide surface width of 4.2 cm. The average yield of the crystal rod with this wide surface size in subsequent processing is 78.45%. A higher yield can improve the utilization rate and production efficiency of single crystal silicon materials and reduce production costs. Controlling the rotation speed and pulling speed of the eccentric seed crystal within a specific range (10rpm to 15rpm and 0.8mm / min to 1mm / min) during crystal pulling helps to maintain stable growth conditions, reduce fluctuations and defects in the growth process, and thus improve the overall quality of the crystal.
[0021] Preferably, in S10, a unimorphic seed crystal is selected, whose crystallographic orientation has an angle deviation of 1.5° from the target crystal orientation 111, and a 1.5° <111> For the eccentric seed crystal, the width of the wide side of the crystal rod is relatively appropriate, neither too large nor too small, and the yield of the crystal rod is also maintained at a high level. There will be no yield loss due to the inability to process the wide side, and there will be no risk of misjudging whether the crystal rod is NG. The average yield is 78.6%, which is relatively good.
[0022] Wherein, in S10, the diameter of the eutectic seed crystal is 5 mm to 10 mm.
[0023] While reducing the yield of single crystal silicon rods, in order to ensure that the 111 CZ single crystal silicon rods finally produced can meet specific electrical performance requirements, specifically, in S20, high-purity polycrystalline silicon is used as a raw material, and an appropriate amount of dopant is added to the raw material to meet the electrical performance requirements of the final product. By selecting high-purity polycrystalline silicon as a raw material and adding an appropriate amount of dopant, in this embodiment, the dopant is boron, the electrical conductivity and other related electrical properties of the silicon rod can be accurately regulated to meet the needs of different application fields. By accurately controlling the doping concentration and optimizing the crystal growth process, single crystal silicon rods with excellent electrical properties can be obtained. These silicon rods have higher electrical conductivity, lower resistivity and better stability, are suitable for manufacturing high-performance semiconductor devices and integrated circuits and other application fields, and can improve the product qualification rate.
[0024] In order to prevent the silicon rod from being contaminated and oxidized during the growth process and ensure the quality and performance of the final product, further, in S20, the flow rate of the inert gas is 50slm to 100slm. The inert gas (such as argon, helium, etc.) plays a protective role in the growth process of the CZ single crystal silicon rod, and can remove harmful substances such as oxygen and water vapor in the air to prevent the silicon rod from being oxidized or contaminated during the growth process. In this embodiment, by accurately adjusting the flow rate of the inert gas, the atmosphere composition in the growth chamber can be further controlled, which can optimize the crystal growth conditions, reduce defects and improve the crystal quality.
[0025] Furthermore, in S30, the crucible rotation speed is 5rpm to 10rpm, and the rotation of the crucible helps to evenly distribute and flow the molten silicon in the crucible. In this embodiment, by precisely controlling the crucible rotation speed within the range of 5rpm to 10rpm, the convection of the molten silicon can be promoted, and the thermal stress caused by the temperature gradient can be reduced, thereby optimizing the flow and temperature distribution of the molten silicon, improving the crystal quality and wide surface flatness of the single crystal silicon rod, and meeting the demand for high-quality semiconductor materials.
[0026] Furthermore, in S30, the furnace pressure is 5KPa to 10KPa. In this embodiment, the furnace pressure is precisely controlled within the range of 5KPa to 10KPa, which helps to reduce defects such as dislocations and inclusions in the single crystal silicon rod, thereby improving the purity and integrity of the crystal and obtaining high-quality single crystal silicon rods. In addition, the appropriate furnace pressure can also stabilize the growth rate of the crystal, ensuring that the crystal maintains a uniform growth rate during the growth process, thereby obtaining a more uniform and stable crystal structure. Optimizing the furnace pressure can reduce interruptions and defective products during the growth process, and improve production efficiency and product qualification rate. At the same time, high-quality crystals also help reduce waste and costs in subsequent processing.
[0027] Wherein, in said S30, the diameter of the single crystal silicon rod obtained by pulling is 150 mm to 250 mm. In this embodiment, the diameter of the single crystal silicon rod obtained by pulling is 200 mm.
[0028] The single crystal silicon rod product is prepared according to the above method of adjusting the wide surface of the 111 Czochralski single crystal silicon rod.
[0029] 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.
[0030] Comparative Example A 111 Czochralski single crystal silicon rod was pulled using a positive crystal seed crystal. The process conditions for pulling the crystal were as follows: pulling speed 0.9 mm / min, crystal rod rotation speed 12 rpm, crucible rotation speed 80 rpm, furnace pressure 8 KPa, and inert gas flow rate 75 slm. A single crystal silicon rod was pulled, and the average width of the wide surface of the single crystal silicon rod was measured, and the yield was statistically calculated. The results are shown in Table 1. Example 1
[0031] The 111 CZ single crystal silicon rod was pulled using a 0.5 degree eccentric seed crystal. The process conditions for pulling the crystal were: pulling speed 0.9 mm / min, crystal rod rotation speed 12 rpm, crucible rotation speed 80 rpm, furnace pressure 8 KPa, inert gas flow rate 75 slm. The single crystal silicon rod was pulled, the average width of the wide surface of the single crystal silicon rod was measured, and the yield was calculated. The specific results are shown in Table 1 Example 2
[0032] A 111 CZ single crystal silicon rod was pulled using a 1 degree eutectic seed crystal. The process conditions for pulling the crystal were: pulling speed 0.9 mm / min, crystal rod rotation speed 12 rpm, crucible rotation speed 80 rpm, furnace pressure 8 KPa, inert gas flow rate 75 slm, and a single crystal silicon rod was pulled. The average width of the wide side of the single crystal silicon rod was measured, and the yield was calculated. The results are shown in Table 1. Example 3
[0033] A 111 CZ single crystal silicon rod was pulled using a 1.5 degree eccentric seed crystal. The process conditions for pulling the crystal were: pulling speed 0.9 mm / min, crystal rod rotation speed 12 rpm, crucible rotation speed 80 rpm, furnace pressure 8 KPa, inert gas flow rate 75 slm, and a single crystal silicon rod was pulled. The average width of the wide side of the single crystal silicon rod was measured, and the yield was calculated. The results are shown in Table 1. Example 4
[0034] A 111 CZ single crystal silicon rod was pulled using a 2-degree eutectic seed crystal. The process conditions for pulling the crystal were: pulling speed 0.9 mm / min, crystal rod rotation speed 12 rpm, crucible rotation speed 80 rpm, furnace pressure 8 KPa, inert gas flow rate 75 slm, and a single crystal silicon rod was pulled. The average width of the wide side of the single crystal silicon rod was measured, and its yield was statistically calculated. The results are shown in Table 1: Table 1 Data comparison table
[0035] It can be seen from the data in Table 1 that the conventional <111> The positive crystal is pulled towards the seed crystal to pull the single crystal silicon rod, and the wide surface of the crystal rod appears. The wide surface is small in the early stage of equal diameter, about 5cm to 7cm; the wide surface becomes larger as the equal diameter is reached, and the wide surface reaches about 10cm to 11cm at the end of the equal diameter of about 250mm. This makes it impossible to roll and grind the ingot in the later stage of equal diameter, resulting in a significant loss of yield; It can be seen from the data in Table 1 Example 1 that: <111> The polarized seed crystal was used to pull the CZ single crystal silicon rod. The polarized seed crystal with a smaller polarized angle of 0.5 degrees was selected first. The wide width of the crystal rod showed a decreasing trend. In the later stage of equal diameter, there was still a length of the crystal ingot that could not be processed due to the large wide surface, but its length was shortened. The yield rate of the crystal rod was improved compared with the first experiment. From the data in Example 2 in Table 1, it can be seen that: using a slightly larger 1 degree polarization angle <111> For the eccentric seed crystal, the width of the wide surface of the crystal rod is further reduced, and the entire crystal rod can basically be tumbled. However, when the convection in the furnace is unstable and the diameter of the crystal rod fluctuates, the yield of the crystal rod may be slightly reduced.
[0036] From the data in Example 3 in Table 1, it can be seen that the use of a 1.5 degree polarization angle that is larger than 1 degree is selected. <111> In the eccentric seed crystal experiment, the width of the wide surface of the crystal rod is reduced, and the width of the wide surface of the whole rod is relatively uniform. The whole crystal rod can be tumbled. Moreover, when the convection in the furnace is unstable and the diameter of the crystal rod fluctuates slightly, the yield of the crystal rod can be guaranteed to a certain extent. It can be seen from the data in Table 1 Example 4 that when using 2 degrees <111> When the crystal is pulled towards the seed crystal by eccentric crystallization, the wide surface of the crystal rod becomes very small. The wide surface in the early and middle stages of equal diameter even becomes a thin crystal line. Only in the late stage of equal diameter does a very small wide surface appear. Combined with the actual production on site and considering the auxiliary role of the wide surface in determining the crystal state, it is not the optimal condition for the wide surface to be too small or disappear.
[0037] In summary, in Example 3, 1.5 degrees <111> For the eccentric seed crystal, the width of the wide side of the crystal rod is more appropriate, neither too large nor too small, and the yield of the crystal rod is also maintained at a high level. There will be no yield loss due to the inability to process the wide side, and there will be no risk of misjudging whether the crystal rod is NG, and the effect is better.
[0038] 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 method for adjusting the width of a 111 CZ silicon rod, characterized in that: The following steps are involved: S10: selecting a eutectic seed crystal, whose crystallographic orientation has an angle deviation of 1° to 1.5° from the target crystal direction 111, and polishing its surface to ensure that it is free of damage and contamination; S20: selecting raw materials, placing them in a quartz crucible, and heating them under the protection of an inert gas to completely melt them to obtain a melt; S30: slowly lowering the eccentric seed crystal to the surface of the melt to make the eccentric seed crystal start to grow, controlling the rotation speed of the eccentric seed crystal to 10 rpm to 15 rpm, and the pulling speed to 0.8 mm / min to 1 mm / min, to obtain a single crystal silicon rod.
2. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In S10 , a unidirectional seed crystal is selected, and its crystallographic orientation has an angular deviation of 1.5° from the target crystal orientation 111 .
3. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In the S10, the diameter of the eutectic seed crystal is 5 mm to 10 mm.
4. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In S20, high-purity polysilicon is used as a raw material, and an appropriate amount of dopant is added to the raw material to meet the electrical performance requirements of the final product.
5. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In S20, the flow rate of the inert gas is 50 slm to 100 slm.
6. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In the above S30, the crucible rotation speed is 5 rpm to 10 rpm.
7. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In the S30, the furnace pressure is 5 KPa to 10 KPa.
8. The method for adjusting the width of a 111 Czochralski single crystal silicon rod according to claim 1, characterized in that: In the S30, the diameter of the drawn single crystal silicon rod is 150 mm to 250 mm.
9. A single crystal silicon rod product prepared by the method for adjusting the wide surface of a 111 Czochralski single crystal silicon rod according to any one of claims 1 to 8.