A method for producing phosphorus and antimony co-doped N-type BC crystal rods based on multi-section furnace pressure and argon flow collaborative regulation process
Patent Information
- Application Number
- CN202611118473.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-09-29
AI Technical Summary
[0005]现有技术中存在的问题是：常规固定炉压等径生长制备的磷、锑共掺杂N型BC晶棒的电阻率波动大，晶棒头部和尾部电阻率的差值很难低于10%，且晶棒中氧含量很难控制在10.5ppma以下（氧含量超标（大于10.5ppma）会增加晶棒中氧的沉积风险，形成“氧环”，降低电池的少子寿命、短路电流、填充因子FF，最终导致转换效率下降，电池片滑档）
（1）常规N型单晶硅棒切片得到的N型硅片用于BC电池片的生产，但光电转换效率偏低，良率偏低，量产难度大。本发明提出的多段式炉压与氩气流协同调控工艺，针对磷、锑共掺杂的N型单晶硅棒生长特性，将等径生长过程划分为多个连续阶段，并对每个阶段的炉压、氩气流量和提拉速度进行差异化设定。这种分段式的操作方式能够在晶棒不同长度位置，对锑元素的挥发速率进行针对性调节。在晶棒生长前期配合较低的炉压和流量，抑制锑元素过度挥发；在中期逐步提高炉压和流量，匹配因分凝效应带来的杂质浓度变化；在后期调整参数，补偿分凝加剧带来的影响。通过该协同作用，能够有效抵消杂质分凝效应与挥发效应的差异，将制备所得整根晶棒头尾电阻率的差值压缩至10%以内，极大地提升了晶棒电阻率集中度，本发明所获N型BC硅片完美匹配BC电池工艺的电阻率集中性难题，且有效控制硅片中氧含量小于10.5ppma，有效提升了硅片的产品良率，大大提升了BC电池片的光电转换效率；
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Abstract
Description
Technical Field
[0001] This invention relates to the field of N-type single crystal silicon rod technology, and specifically to a method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a multi-stage furnace pressure and argon gas flow coordinated control process. Background Technology
[0002] Back-contact solar cells, a high-efficiency crystalline silicon solar cell technology, have their PN junctions and metal electrodes all located on the back of the cell, with no grid lines on the front. Because the front is unobstructed, light absorption is maximized, effectively improving conversion efficiency. Simultaneously, the all-black front appearance meets the aesthetic requirements of distributed photovoltaic (PV) applications such as building-integrated photovoltaics (BIPV). Furthermore, this type of cell also offers advantages in temperature coefficient, low-light performance, and degradation rate.
[0003] Back-contact solar cells place stringent requirements on the N-type silicon substrate used, necessitating a narrow resistivity range and high resistivity concentration. To meet this requirement, N-type silicon wafers co-doped with phosphorus and antimony are currently widely used. During single-crystal growth, resistivity is affected by both impurity segregation and volatilization effects. Impurity segregation results in lower resistivity at the tail end and higher resistivity at the head end of the crystal rod, while impurity volatilization results in higher resistivity at the tail end and lower resistivity at the head end. By utilizing these two opposing mechanisms, the resistivity difference between the head and tail ends can be reduced across the entire crystal rod, thereby increasing the resistivity concentration.
[0004] In current production processes, single-crystal furnaces primarily regulate the antimony volatilization rate by controlling the furnace pressure, thereby altering the impurity concentration in the melt and the final resistivity of the crystal rod. However, existing processes mostly employ fixed furnace pressures for growth, making it impossible to differentiate the antimony volatilization rate at different lengths of the crystal rod, such as the head, middle, and tail. To compensate for uneven doping, most processes currently rely on retaining a high crucible weight exceeding 35% of the total feed amount. This operating mode results in low raw material utilization and high production costs, making it difficult to meet the practical requirements of centralized control over silicon wafer resistivity in the mass production stage of back-contact solar cells. Summary of the Invention
[0005] The existing technology has the following problems: the resistivity of phosphorus and antimony co-doped N-type BC ingots prepared by conventional fixed furnace pressure constant diameter growth has large fluctuations, and the difference in resistivity between the head and tail of the ingot is difficult to be less than 10%. Furthermore, it is difficult to control the oxygen content in the ingot below 10.5 ppma (excessive oxygen content (greater than 10.5 ppma) increases the risk of oxygen deposition in the ingot, forming an "oxygen ring," reducing the minority carrier lifetime, short-circuit current, and fill factor FF of the battery, ultimately leading to a decrease in conversion efficiency and cell slippage). To address these problems, this invention provides a method for producing phosphorus and antimony co-doped N-type BC ingots based on a segmented furnace pressure and argon gas flow synergistic control process, comprising the following preparation steps: Phosphorus and antimony co-doped polycrystalline silicon melt enters the constant diameter growth stage through crystal pulling, shoulder formation, and shoulder rotation. During crystal pulling, shoulder formation, and shoulder rotation, the constant crucible rotation is 5-6 rpm, the furnace pressure is 6-7 Torr, and the argon flow rate is 90-100 slpm. During constant diameter growth: During the 0-80mm diameter stage, after the constant-pressure crucible is raised to the top crucible, crystal pulling begins once the liquid level in the crucible drops to the distance between the crystal pulling liquid outlet and the top crucible. The crystal rod pulling speed is 79-82mm / h, the furnace pressure is maintained at 5 Torr, and the argon flow rate is 90 slpm. During the 80-200mm diameter stage, the crystal pulling speed is 82-88mm / h, the furnace pressure is maintained at 5-6 Torr, and the argon flow rate is 90-98 slpm; During the 200-500mm diameter stage, the crystal pulling speed is 88-94mm / h, the furnace pressure is maintained at 6-6.5 Torr, and the argon flow rate is 98-105 slpm; In the 500-3000mm diameter stage, the crystal pulling speed is 95-97mm / h, the furnace pressure is maintained at 7 Torr, and the argon flow rate is 110 slpm; In the constant diameter section, the ingot pulling speed is 92-95 mm / h, the furnace pressure is maintained at 5.8 Torr, and the argon flow rate is 110 slpm; After the constant diameter growth is completed, a finishing operation is performed to obtain a phosphorus and antimony co-doped N-type BC crystal rod.
[0006] Preferably, the finishing operations after the equal diameter growth process include the following steps: Preferably, the preparation method of phosphorus and antimony co-doped silicon melt includes the following steps: (1) The high-purity polycrystalline silicon and phosphorus dopant were precisely weighed and placed in a high-purity quartz crucible and placed in the main chamber of a Kex 1600 single crystal furnace. They were heated and completely melted under the protection of high-purity argon to obtain phosphorus-doped melt. The furnace pressure was 5 torr, the furnace pressure deviation was ±4 torr, and the melting power was 95 KW ±0.1 KW. (2) Then, the antimony-containing master alloy dopant is added in batches and multiple times to the phosphorus-doped melt obtained in step (1) through the sub-chamber of the single crystal furnace. Before adding the antimony dopant, the gas in the sub-chamber of the single crystal furnace needs to be replaced with high-purity argon gas, and the pressure in the sub-chamber of the single crystal furnace needs to be adjusted to be consistent with the pressure in the main chamber of the single crystal furnace. Then, it is heated and melted evenly to obtain phosphorus and antimony co-doped polycrystalline silicon melt.
[0007] Preferably, the phosphorus dopant is a black N-type phosphorus-doped alloy with a resistivity of 0.001-0.005 Ω·cm.
[0008] Preferably, the antimony dopant is high-purity antimony with a purity of 7N and a particle size of 1-3mm.
[0009] Preferably, the purity of the high-purity polycrystalline silicon is 6N-9N.
[0010] Preferably, the furnace temperature during the constant diameter growth stage is 1450±10℃.
[0011] Preferably, the resistivity of the phosphorus and antimony co-doped N-type BC crystal rod is 10-50 Ω·cm.
[0012] Beneficial effects: (1) Conventional N-type silicon wafers obtained by slicing N-type monocrystalline silicon rods are used for the production of BC solar cells, but the photoelectric conversion efficiency is low, the yield is low, and mass production is difficult. The multi-stage furnace pressure and argon flow coordinated control process proposed in this invention is designed for the growth characteristics of phosphorus and antimony co-doped N-type monocrystalline silicon rods. The constant diameter growth process is divided into multiple continuous stages, and the furnace pressure, argon flow rate and pulling speed of each stage are set differently. This segmented operation method can specifically adjust the volatilization rate of antimony at different length positions of the crystal rod. In the early stage of crystal rod growth, a lower furnace pressure and flow rate are used to suppress excessive volatilization of antimony; in the middle stage, the furnace pressure and flow rate are gradually increased to match the changes in impurity concentration caused by segregation effect; in the later stage, the parameters are adjusted to compensate for the impact of intensified segregation. Through this synergistic effect, the difference between the impurity segregation effect and the volatilization effect can be effectively offset, compressing the difference in resistivity between the head and tail of the prepared crystal rod to less than 10%, which greatly improves the resistivity concentration of the crystal rod. The N-type BC silicon wafer obtained by this invention perfectly matches the resistivity concentration problem of BC cell process, and effectively controls the oxygen content in the silicon wafer to less than 10.5 ppma, which effectively improves the product yield of silicon wafer and greatly improves the photoelectric conversion efficiency of BC cell. (2) In the crystal pulling process, the present invention does not require a large amount of residual melt to offset the problem of uneven doping. Compared with the existing process, which requires a high crucible retention of more than 35% of the feed amount, the process of the present invention can significantly reduce this proportion. The direct effect of this improvement is that the raw material utilization rate of a single furnace is significantly improved, and more qualified crystal rods can be produced in a single feed, reducing the waste of polycrystalline silicon raw materials and the subsequent recycling process, which is of great help to reduce the production cost of BC battery substrate materials.
[0013] (3) In the method of this invention, by setting multiple process steps at different points in the equal diameter stage, the parameter settings are more in line with the actual situation of physical volatilization and segregation, rather than maintaining a single fixed static furnace pressure. This reduces the dependence of process control on human experience and makes the resistivity of the crystal rods in each batch more consistent. Combined with the stepwise antimony addition strategy in the melting process of high-purity polycrystalline silicon, the initial uniform distribution of dopants in the melt is further guaranteed. The phosphorus and antimony co-doped BC crystal rods produced exhibit more consistent conductivity after being sliced into solar cells, which can meet the stringent requirements for controlling the resistivity of silicon wafer substrate in the mass production of back contact cells. Detailed Implementation
[0014] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.
[0015] The high-purity polycrystalline silicon material used in the following embodiments of the present invention has a purity of 9N.
[0016] The phosphorus dopant is a black N-type phosphorus-doped alloy with a resistivity of 0.001 Ω·cm, purchased from Chuxiong Chuanzhi Electronic Materials Co., Ltd. The antimony dopant is high-purity antimony, model Sb-07, also purchased from Chuxiong Chuanzhi Electronic Materials Co., Ltd. Example 1 A method for preparing a phosphorus-antimony co-doped N-type single-crystal silicon rod (11 inches (277 mm) in diameter, with a target resistivity of 12 Ω·cm) is as follows: (1) 500 kg of high-purity polycrystalline silicon material and 20 g of phosphorus dopant were precisely weighed and placed in a high-purity quartz crucible and placed in the main chamber of Liancheng Kaikes 380PV-1600 single crystal furnace. The mixture was heated and completely melted under the protection of high-purity argon gas to obtain phosphorus-doped melt. The furnace pressure was 5 torr and the melting power was 95 KW. (2) Then, antimony dopant is added in five portions (each time the amount added is 110 kg) to the phosphorus-doped melt obtained in step (1) through the sub-chamber of the single crystal furnace. Before adding the antimony dopant, the gas in the sub-chamber of the single crystal furnace needs to be replaced with high-purity argon gas, and the pressure in the sub-chamber of the single crystal furnace needs to be adjusted to be consistent with the pressure in the main chamber of the single crystal furnace. Then, it is heated and melted evenly to obtain phosphorus and antimony co-doped polycrystalline silicon melt. (3) The phosphorus and antimony co-doped polycrystalline silicon melt enters the constant diameter growth stage through crystal pulling, shoulder forming, and shoulder turning. During crystal pulling, shoulder forming, and shoulder turning, the constant crucible rotation is 6 rpm, the furnace pressure is 7 Torr, and the argon flow rate is 100 slpm. The process parameters for constant diameter growth are shown in Table 1: Table 1
[0017] (4) After the constant diameter growth is completed, the finishing work is carried out. The furnace pressure is maintained at 5.8 Torr, the power is increased to 21 kW, and the argon flow rate is maintained at 110 slpm to obtain a conical crystal rod tail with a length of about 150 mm and an end diameter of 100 mm. At the same time, phosphorus and antimony co-doped N-type BC single crystal silicon rods are obtained.
[0018] The technical parameters of the phosphorus and antimony co-doped N-type single crystal silicon rod obtained in Example 1 are shown in Table 2: As can be seen from the test data in Table 2, the resistivity deviation at the head and tail of the phosphorus and antimony co-doped single crystal silicon rod obtained in Example 1 is 1.02 Ω·cm, and the resistivity fluctuation is 6.89%, which is less than 10%.
[0019] Table 2
[0020] Comparative Example 1 is the same as Example 1, except that the process parameters for the equal diameter growth process in Comparative Example 1 are shown in Table 3: Table 3
[0021] Comparative Example 2 is the same as Example 1, except that the process parameters for the equal diameter growth process in Comparative Example 2 are shown in Table 4: Table 4
[0022] Comparative Example 3 is the same as Example 1, except that the process parameters for the equal diameter growth process in Comparative Example 3 are shown in Table 5: Table 5
[0023] The test results show that the technical parameters of the phosphorus and antimony co-doped single crystal silicon rods obtained in Comparative Example 1, Comparative Example 2, and Comparative Example 3 are shown in Table 6: Table 6 .
[0024] Example 2 A method for preparing a phosphorus-antimony co-doped N-type single-crystal silicon rod (3735 mm in length, 301 mm in diameter, and target resistivity of 1.14 Ω·cm) is as follows: (1) 500 kg of high-purity polycrystalline silicon material and 120 g of phosphorus dopant were precisely weighed and placed in a high-purity quartz crucible and placed in the main chamber of a single crystal furnace. The crucible was heated and completely melted under the protection of high-purity argon gas to obtain phosphorus-doped melt. The furnace pressure was 5 torr and the melting power was 95 KW. (2) Then, antimony dopant is added in five portions (about 130 kg each time) through the sub-chamber of the single crystal furnace to the phosphorus-doped melt obtained in step (1). Before adding the antimony dopant, the gas in the sub-chamber of the single crystal furnace needs to be replaced with high-purity argon gas, and the pressure in the sub-chamber of the single crystal furnace needs to be adjusted to be consistent with the pressure in the main chamber of the single crystal furnace. Then, it is heated and melted evenly to obtain phosphorus and antimony co-doped polycrystalline silicon melt. (3) The phosphorus and antimony co-doped polycrystalline silicon melt enters the constant diameter growth stage through crystal pulling, shoulder forming, and shoulder turning. During crystal pulling, shoulder forming, and shoulder turning, the constant crucible rotation is 5 rpm, the furnace pressure is 6 Torr, and the argon flow rate is 90 slpm. The process parameters for constant diameter growth are shown in Table 7: Table 7
[0025] (4) After the constant diameter growth is completed, the finishing work is carried out. The furnace pressure is maintained at 5.8 Torr, the power is increased to 21 kW, and the argon flow rate is maintained at 110 slpm to obtain a conical crystal rod tail with a length of about 300 mm and an end diameter of 110 mm. At the same time, phosphorus and antimony co-doped N-type BC single crystal silicon rods are obtained.
[0026] The technical parameters of the phosphorus and antimony co-doped N-type single crystal silicon rod obtained in Example 2 are shown in Table 8:
[0027] Table 8
[0028] As can be seen from the test data in Table 8, the resistivity deviation at the head and tail of the phosphorus and antimony co-doped single crystal silicon rod obtained in Example 1 is 0.07 Ω·cm, and the resistivity fluctuation is 5.69%, which is less than 10%.
[0029] Comparative Example 4 is the same as Example 2, except that the process parameters for the equal diameter growth process in Comparative Example 4 are shown in Table 9: Table 9
[0030] Comparative Example 5 is the same as Example 2, except that the process parameters for the equal diameter growth process in Comparative Example 5 are shown in Table 10: Table 10
[0031] Comparative Example 6 is the same as Example 2, except that the process parameters for the equal diameter growth process in Comparative Example 6 are shown in Table 11: Table 11
[0032] The test results show that the technical parameters of the phosphorus and antimony co-doped single crystal silicon rods obtained in Comparative Examples 4, 5, and 6 are shown in Table 12: Table 12
[0033] Application performance testing The crystal rods obtained in Examples 1 and 2 of the present invention were sliced to form silicon wafers.
[0034] The silicon wafer obtained in Example 1 had a thickness of 130 μm and dimensions of 183.75 mm × 210 mm. It was used to form photovoltaic BC cells using the BC cell process (cleaning, polishing, oxidation – phosphorus diffusion – boron diffusion – front-side ALD – back-side PECVD – silver-free electroplating – inspection and sorting). The photoelectric conversion efficiency of the obtained photovoltaic cells was tested according to the cell production line. The test results are shown in Table 13.
[0035] The silicon wafer obtained in Example 2 had a thickness of 130 μm and a size of 210 mm × 210 mm. It was used to form photovoltaic cells according to the BC cell process (cleaning, polishing, oxidation – phosphorus diffusion – boron diffusion – front ALD – back PECVD – silver-free electroplating – inspection and sorting). The photoelectric conversion efficiency of the obtained photovoltaic cells was tested according to the cell production line. The test results are shown in Table 13.
[0036] Comparative Example 1 uses a conventional photovoltaic cell, a TOPCon TNC-G12R cell fabricated from an N-type silicon wafer manufactured by Huayao Optoelectronics Technology Co., Ltd., with a thickness of 150 μm and dimensions of 183.75 mm × 210 μm. The photoelectric conversion efficiency of the photovoltaic cell in Comparative Example 1 was tested. The test results are shown in Table 13.
[0037] Table 13
[0038] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.
Claims
1. A method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process, characterized in that, The preparation steps include the following: Phosphorus and antimony co-doped polycrystalline silicon melt enters the constant diameter growth stage through crystal pulling, shoulder formation, and shoulder rotation. During crystal pulling, shoulder formation, and shoulder rotation, the constant crucible rotation is 5-6 rpm, the furnace pressure is 6-7 Torr, and the argon flow rate is 90-100 slpm. During constant diameter growth: During the 0-80mm diameter stage, after the constant-pressure crucible is raised to the top crucible, crystal pulling begins once the liquid level in the crucible drops to the distance between the crystal pulling liquid outlet and the top crucible. The crystal rod pulling speed is 79-82mm / h, the furnace pressure is maintained at 5 Torr, and the argon flow rate is 90 slpm. During the 80-200mm diameter stage, the crystal pulling speed is 82-88mm / h, the furnace pressure is maintained at 6 Torr, and the argon flow rate is 90-98 slpm; In the 200-500mm diameter stage, the crystal pulling speed is 88-94mm / h, the furnace pressure is maintained at 7 Torr, and the argon flow rate is 98-105 slpm; During the 500-3000mm diameter stage, the crystal pulling speed is 95-97mm / h, the furnace pressure is maintained at 7 Torr, and the argon flow rate is 110 slpm; In the constant diameter section, the ingot pulling speed is 92-95 mm / h, the furnace pressure is maintained at 5.8 Torr, and the argon flow rate is 110 slpm; After the constant diameter growth is completed, a finishing operation is performed to obtain phosphorus and antimony co-doped BC crystal rods.
2. The method for producing phosphorus and antimony co-doped BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 1, characterized in that, The preparation method of phosphorus and antimony co-doped silicon melt includes the following steps: (1) The high-purity polycrystalline silicon and phosphorus dopant were precisely weighed and placed in a high-purity quartz crucible and placed in the main chamber of a single crystal furnace. They were heated and completely melted under the protection of high-purity argon to obtain phosphorus-doped melt. The furnace pressure was 5 torr, the furnace pressure deviation was ±4 torr, and the melting power was 95 KW ±0.1 KW. (2) Then, antimony dopant is added in batches and weighed in multiple batches to the phosphorus-doped molten material obtained in step (1) through the sub-chamber of the single crystal furnace. Before adding the antimony dopant, the gas in the sub-chamber of the single crystal furnace needs to be replaced with high-purity argon gas, and the pressure in the sub-chamber of the single crystal furnace needs to be adjusted to be consistent with the pressure in the main chamber of the single crystal furnace. Then, it is heated and melted evenly to obtain phosphorus and antimony co-doped polycrystalline silicon molten material.
3. The method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 2, characterized in that, The phosphorus dopant is a black N-type phosphorus-doped alloy with a resistivity of 0.001-0.005 Ω·cm.
4. The method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 2, characterized in that, The antimony dopant is high-purity antimony, with a purity of 7N and a particle size of 1-3mm.
5. The method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 2, characterized in that, The purity of high-purity polycrystalline silicon is 6N-9N.
6. The method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 1, characterized in that, The furnace temperature during the constant diameter growth stage is 1450±10℃.
7. The method for producing phosphorus and antimony co-doped N-type BC crystal rods based on a segmented furnace pressure and argon gas flow synergistic control process according to claim 1, characterized in that, The resistivity of phosphorus and antimony co-doped N-type BC crystal rods is 10-50 Ω·cm, and the oxygen content of the crystal rods is less than 10.5 ppma.