Method for prolonging service life of boron diffusion quartz device

Abstract

The invention belongs to the technical field of battery manufacturing, and particularly relates to a method for prolonging the service life of a boron diffusion quartz device, which comprises the following steps: S1, pretreatment: carrying out RCA standard cleaning on a silicon wafer; s2, wafer loading and furnace tube pretreatment: loading the cleaned silicon wafer to a quartz boat, feeding the quartz boat into a tubular diffusion furnace, and carrying out nitrogen purging to remove residual air in the furnace tube; s3, raising the temperature, carrying out closed tube leakage detection, and after stabilization, detecting the sealing performance of the furnace tube in a nitrogen pressure maintaining mode; s4, pre-oxidation: forming a thin oxidation film layer on the surface of the silicon wafer; s5, boron source deposition; s6, carrying out propelling treatment; s7, post-oxidation is carried out, and a BSG layer is prepared; s8, back pressure purging and cooling are carried out; and S9, taking the sheet. The core oxidation temperature can be reduced from 1040 DEG C to 1000 DEG C or below and is far away from the softening temperature of a quartz material, softening deformation of devices such as a quartz furnace tube and a quartz boat is remarkably reduced, the service life of the devices is prolonged, and the accessory replacement and production line shutdown cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of battery manufacturing technology, specifically relating to a method for extending the service life of boron-deposited quartz devices. Background Technology

[0002] As a core component of clean and renewable energy, photovoltaic energy occupies a key position in the global energy structure transformation. TOPCON cells, with their advantages of high conversion efficiency and long lifespan, have become one of the mainstream technologies in the current photovoltaic cell field. In the TOPCON cell manufacturing process, the boron diffusion process is the core step in forming the PN junction. Its core objective is to achieve uniform doping of boron atoms on the surface of the N-type silicon wafer and to prepare a boron-doped silicon oxide layer (BSG layer) with a thickness of ≥90nm. This BSG layer needs to effectively protect the front boron-doped layer from corrosion in the subsequent RCA edge-wrap plating process, which directly affects the electrical performance and structural stability of the cell.

[0003] However, existing boron diffusion processes have core technological limitations that severely restrict production line stability and production cost control:

[0004] Quartz devices suffer from rapid wear and tear, resulting in high production line maintenance costs. Traditional boron diffusion processes, to meet the requirements for preparing BSG layers larger than 90nm, require a high-temperature environment of 1040℃, introducing a large amount of oxygen at 28000 sccm and maintaining a reaction time of 4200s. This temperature is close to the softening temperature of quartz material. Sustained high temperatures can cause irreversible softening and deformation of quartz devices. Deformation of the quartz furnace tube disrupts the uniformity of the airflow within the furnace, leading to decreased consistency in boron diffusion. Deformation of the quartz boat can easily cause wafer jamming and breakage during loading and unloading, reducing product yield. Deformed quartz devices require frequent replacement, increasing not only the cost of spare parts but also extending production line downtime and limiting production efficiency.

[0005] Therefore, developing a boron diffusion process that can reduce the loss of quartz devices has significant industrial application value and technological innovation significance. Summary of the Invention

[0006] The purpose of this invention is to provide a method for extending the service life of boron-doped quartz devices. This method can reduce the core oxidation temperature from 1040℃ to below 1000℃, which is far from the softening temperature of quartz materials. This significantly reduces the softening and deformation of devices such as quartz furnace tubes and quartz boats, extending their service life and reducing the cost of parts replacement and production line downtime. At the same time, by using progressive flow control and segmented switching, it ensures uniform boron atom doping and a BSG layer thickness of ≥90nm, ensuring that the battery's electrical performance and structural stability are no less than those of traditional processes.

[0007] The specific technical solution adopted by this invention is as follows:

[0008] A method for extending the service life of boron-deposited quartz devices includes the following steps:

[0009] S1: Pre-treatment, RCA standard cleaning of silicon wafers;

[0010] S2: Wafer loading and furnace tube pretreatment: The cleaned silicon wafers are loaded into a quartz boat and sent into a tube diffusion furnace for nitrogen purging to remove residual air in the furnace tube.

[0011] S3: Heat up and perform a closed-tube leak test. After stabilization, test the furnace tube sealing performance using nitrogen pressure testing.

[0012] S4: Pre-oxidation, forming a thin oxide film on the silicon wafer surface;

[0013] S5: Boron source deposition;

[0014] S6: Propulsion processing;

[0015] S7: Post-oxidation to prepare the BSG layer;

[0016] S8: Back pressure purging and cooling;

[0017] S9: Take the film.

[0018] S2 includes:

[0019] S21: Wafer loading, loading the silicon wafers face up into the quartz boat;

[0020] S22: Furnace tube pretreatment. The quartz boat is sent into the effective reaction zone of the furnace tube and aligned in the center. After the furnace door is closed, nitrogen gas is introduced for purging.

[0021] S3 specifically includes:

[0022] S31: Temperature control, nitrogen gas is introduced during the heating process to maintain the furnace pressure at 150mbar;

[0023] S32: Temperature is stable, and it remains stable for 30 seconds after reaching 825℃ to ensure a uniform temperature field inside the furnace tube;

[0024] S33: Closed-pipe leak detection.

[0025] S4 specifically includes:

[0026] S41: Atmosphere configuration, adjust the furnace pressure to 170mbar, control the oxygen to nitrogen flow ratio to 1:5 through the gas mixer, mix for 30s to ensure gas uniformity;

[0027] S42: Pre-oxidation treatment, maintaining 825℃, 170mbar pressure and the above atmosphere, for 300s to form an oxide film with a thickness of 5-8nm on the silicon wafer surface.

[0028] S5 employs progressive flow control, which includes the following steps:

[0029] S51: Deposition of low-concentration boron source, maintaining furnace temperature at 825℃ and pressure at 170mbar, introducing oxygen at 400sccm and nitrogen at 1700sccm, stabilizing for 30s, then introducing boron trichloride, and depositing for 180s.

[0030] S52: Deposition of medium-concentration boron source, heating to 835℃ at a rate of 3℃ / min and stabilizing for 20s, maintaining constant gas flow rate, deposition for 180s;

[0031] S53: High-concentration boron source deposition, heating to 845℃ at a rate of 3℃ / min and stabilizing for 20s, maintaining the above gas environment, deposition for 180s, so that the boron atom penetration depth reaches 50-60nm, forming a PN junction.

[0032] S6 specifically includes:

[0033] S61: Atmosphere switching, close the boron source channel, and switch to a pure nitrogen reducing atmosphere;

[0034] S62: Temperature control, heating to 900℃ at a rate of 4℃ / min and stabilizing for 30s, maintaining furnace pressure of 170mbar and stable nitrogen flow rate;

[0035] S63: Propulsion processing, maintaining 900℃, pure nitrogen atmosphere and 170mbar pressure, processing for 750s, to achieve a PN junction depth of 80-100nm.

[0036] Specifically, S7 includes:

[0037] S71: Atmosphere switching, close the nitrogen channel and switch to high-purity oxygen;

[0038] S72: Temperature control, heating to 1000℃ at a rate of 5℃ / min and stabilizing for 30s, while simultaneously increasing the oxygen flow rate to 28000sccm and the furnace pressure to 900mbar;

[0039] S73: Post-oxidation treatment, maintaining the above temperature, pressure and oxygen flow rate, for 4800s.

[0040] S8 specifically includes:

[0041] S81: Back pressure control, stop heating, maintain oxygen flow rate of 28000sccm, and gradually reduce pressure to atmospheric pressure;

[0042] S82: Nitrogen purging, switch to nitrogen supply, purge for 300 seconds to remove residual gas;

[0043] S83: Cooling treatment, nitrogen gas is continuously introduced to maintain a slight positive pressure inside the furnace, and the temperature is naturally reduced to below 300℃.

[0044] S5 employs pulsed gas supply control, and the tubular diffusion furnace is equipped with a pulsed gas supply controller. Step S5 specifically includes the following steps:

[0045] S51: Temperature control, heating to 840℃ at a rate of 3℃ / min and stabilizing for 20s to ensure uniform temperature inside the furnace;

[0046] S52: Pulse parameter setting, start the pulse air supply controller, set the pulse frequency to 0.5Hz, and each pulse cycle includes 12 seconds of air supply time and 6 seconds of interval time;

[0047] S53: Pulse gas supply deposition, oxygen, nitrogen and high-purity boron trichloride are introduced, furnace pressure is maintained at 170 mbar, deposition time is 540 s, and a uniform boron-rich layer is formed.

[0048] S6 specifically includes:

[0049] S61: Atmosphere switching, close the boron source channel, and switch to a pure nitrogen reducing atmosphere;

[0050] S62: Temperature control, heating to 900℃ at a rate of 4℃ / min and stabilizing for 30s, maintaining furnace pressure of 170mbar and stable nitrogen flow rate;

[0051] S63: Adjust the pulse gas supply frequency to 0.2Hz, with each pulse cycle including 15 seconds of gas supply time and 10 seconds of interval time.

[0052] The technical effects achieved by this invention are as follows:

[0053] This invention optimizes boron diffusion process parameters and gas control strategies to reduce the core oxidation temperature from 1040℃ to below 1000℃, far from the softening temperature of quartz materials. This significantly reduces the softening and deformation of components such as quartz furnace tubes and quartz boats, extending their service life and reducing replacement costs and production line downtime. Simultaneously, through progressive flow control and segmented switching, it ensures uniform boron atom doping and a BSG layer thickness ≥90nm, ensuring that the battery's electrical performance and structural stability are no less than those of traditional processes. This invention balances production line stability, cost control, and product quality, demonstrating significant application value. Attached Figure Description

[0054] Figure 1 This is a flowchart of the present invention;

[0055] Figure 2 This is a schematic diagram showing the process tracking experimental data of the first embodiment of the present invention, with efficiency on par with the production line and no abnormalities in yield.

[0056] Figure 3 This is a schematic diagram showing the process pilot test data of the first embodiment of the present invention, with efficiency comparable to that of the production line; Detailed Implementation

[0057] To make the objectives and advantages of this invention clearer, the invention will be specifically described below with reference to embodiments. It should be understood that the following text is merely used to describe one or more specific embodiments of the invention and does not strictly limit the scope of protection specifically claimed by the invention.

[0058] Example 1:

[0059] like Figures 1-3 As shown, a method for extending the service life of boron-derived quartz devices is based on the diffusion dynamics of boron atoms in silicon. The diffusion coefficient of boron atoms is exponentially positively correlated with temperature, while the adsorption and deposition efficiency of boron atoms is directly related to the concentration of boron source.

[0060] In traditional constant flow processes, a single combination of temperature and concentration cannot simultaneously achieve both uniform surface adhesion and deep internal penetration. While low-concentration boron sources can reduce agglomeration, their diffusion efficiency is low, making it difficult to form a sufficiently thick doped layer. High-concentration boron sources, although diffusing quickly, tend to lead to excessively high surface concentration and atomic agglomeration. This embodiment, however, achieves the following:

[0061] In the low-temperature and low-concentration stage, low-activity boron atoms are slowly adsorbed to form a uniform boron-rich buffer layer, avoiding the direct accumulation of high-concentration boron atoms in the later stage.

[0062] In the intermediate temperature and intermediate concentration stage, increasing the temperature enhances the activity of boron atoms, and simultaneously increases the concentration of the boron source, thus constructing a continuous concentration gradient and laying the foundation for deep diffusion.

[0063] During the high temperature and high concentration stage, the diffusion coefficient of boron atoms is maximized, and the diffusion channels are rapidly filled by a high concentration of boron source to form a dense and uniform PN junction.

[0064] Meanwhile, by combining the atmosphere segmentation switching strategy, the optimal gas environment is matched at different process stages to achieve the functional objectives of buffer layer preparation, doping reaction, deep diffusion, and dense oxide layer formation, thereby further optimizing the process effect.

[0065] It includes the following steps:

[0066] S1: Pre-treatment, RCA standard cleaning of silicon wafers;

[0067] S11: SC-1 cleaning, removes organic contaminants and some metallic impurities;

[0068] Prepare a cleaning solution with the following volume ratio:

[0069] NH4OH(28%):H2O2(30%):H2O=1:1:5

[0070] The cleaning solution temperature is 75℃±2℃;

[0071] Immerse the silicon wafer in the cleaning solution and ultrasonically clean it for 10 minutes. Remove the silicon wafer and rinse it for 5 minutes to ensure that there is no cleaning solution residue on the surface.

[0072] S12: HF etching to remove the natural oxide layer;

[0073] Prepare a etchant solution with the following volume ratio:

[0074] HF (40%):H2O = 1:50

[0075] The temperature of the corrosive solution is 25℃±1℃;

[0076] Immerse the silicon wafer in the etching solution for 30 seconds to remove the 5-10 nm thick natural oxide layer on the surface, rinse for 3 minutes, and then blow dry to ensure that the silicon wafer surface is dry and free of watermarks.

[0077] S13: SC-2 cleaning to remove residual metal impurities;

[0078] Prepare a cleaning solution with the following volume ratio:

[0079] HCl(37%):H2O2(30%):H2O=1:1:6

[0080] The temperature of the cleaning solution is 80℃±2℃;

[0081] Immerse the silicon wafer in the cleaning solution for 15 minutes, rinse for 5 minutes, and then blow dry to complete the cleaning process.

[0082] S2: Load the silicon wafers and pre-treat the furnace tubes;

[0083] S21: Wafer loading. Using a vacuum pen, the cleaned N-type silicon wafers are loaded one by one into the quartz boat, with the front side of the wafers facing up and the edges aligned with the slots in the quartz boat, ensuring uniform wafer spacing and no tilting or overlapping. After loading, the wafers are inspected with an optical microscope to ensure that there are no new wafer chipping or scratches.

[0084] S22: Furnace tube pretreatment, start the tubular diffusion furnace, open the furnace door, and send the quartz boat loaded with silicon wafers into the effective reaction zone of the furnace tube through the transfer device. Align the center of the quartz boat with the center of the furnace tube heating zone, close the furnace door, start nitrogen purging, and remove residual air in the furnace tube.

[0085] S3: Heat the furnace tubes and perform a closed-tube leak test;

[0086] S31: Temperature control, start the temperature control system, set the heating rate to 5℃ / min, target temperature to 825℃, during the heating process, nitrogen gas is continuously introduced to maintain the furnace pressure at 150mbar to prevent oxidation of the silicon wafer surface;

[0087] S32: Temperature stability. After reaching 825℃, maintain the temperature stability for 30 seconds to ensure a uniform temperature field inside the furnace tube.

[0088] S33: Closed-pipe leak test. Close the nitrogen inlet valve and exhaust valve, and start the leak test procedure. Introduce nitrogen into the furnace tube to a pressure of 200 mbar, close the inlet valve, and maintain the pressure for 120 seconds. Collect pressure data in real time through the pressure sensor. If the pressure fluctuation within 120 seconds is ≤ ±5 mbar, the leak test is qualified. If the pressure drop exceeds 5 mbar, check the sealing parts such as the furnace door gasket and gas pipeline interface. Replace the damaged seals and retest the leak until it is qualified.

[0089] S4: Pre-oxidation, forming an oxide film on the silicon wafer surface;

[0090] S41: Atmosphere configuration. After leak testing is passed, open the nitrogen exhaust valve and adjust the furnace pressure to 170 mbar. Adjust the oxygen to nitrogen flow ratio to 1:5 using the gas mixer, turn on the gas mixer, and mix for 30 seconds to ensure uniform gas mixing.

[0091] S42: Pre-oxidation treatment. Maintain the above temperature, pressure, and atmosphere conditions and perform pre-oxidation treatment for 300s. The core purpose of pre-oxidation is to form a thin oxide film with a thickness of 5-8nm on the silicon wafer surface. This oxide film serves as a buffer layer for subsequent boron doping, which can reduce the corrosion of the silicon wafer surface by the boron source and improve the adsorption uniformity of boron atoms.

[0092] S5: Boron source deposition is performed using progressive flow control and segmented atmosphere switching. The boron source is high-purity boron trichloride gas.

[0093] This step is the core stage of boron diffusion, lasting a total of 540 seconds, and is carried out in three stages. The furnace pressure is maintained at a constant 170 mbar throughout the process, and the atmospheric environment is as follows:

[0094] O2 / N2 = 1:3

[0095] This atmosphere promotes the chemical reaction between boron atoms and the silicon wafer surface, while preventing excessive oxidation that could lead to the failure of boron atoms.

[0096] S51: Low-concentration boron source deposition;

[0097] The oxygen flow rate was adjusted to 400 sccm and the nitrogen flow rate to 1700 sccm using a gas mixer, with an O2 / N2 ratio of 1:3. After thorough mixing, the mixture was introduced into the furnace tube and stabilized for 30 seconds. Then, the boron trichloride gas channel was activated, corresponding to a boron atom concentration of 0.2 × 10⁻⁶. 20 / cm 3 Maintain the above parameters and deposit for 180 seconds. The temperature is low during this stage, and the boron atoms are less active. The low concentration of boron source can avoid agglomeration caused by excessive surface concentration and form a uniform boron-rich buffer layer.

[0098] S52: Deposition of medium-concentration boron source;

[0099] The furnace tube temperature was increased to 835℃ at a rate of 3℃ / min, while maintaining a constant gas flow rate to avoid atmospheric fluctuations. After reaching 835℃, the temperature was stabilized for 20 seconds to ensure uniformity. The boron trichloride flow rate was then adjusted to 110 sccm, corresponding to a boron atom concentration of 0.45 × 10⁻⁶. 20 / cm 3 The deposition parameters are maintained for 180 seconds. During this stage, the temperature increases, the diffusion coefficient of boron atoms increases, and the medium-concentration boron source can construct a continuous concentration gradient, laying the foundation for deep diffusion.

[0100] S53: High-concentration boron source deposition;

[0101] Continue to increase the temperature to 845℃ at a rate of 3℃ / min, stabilize for 20s, and maintain the deposition parameters for 180s. The temperature is highest at this stage, and the boron atom diffusion coefficient reaches its peak. The high-concentration boron source can quickly fill the diffusion channel, allowing boron atoms to penetrate into the silicon wafer to a depth of 50-60nm, forming a preliminary PN junction.

[0102] S6: Propulsion process to allow boron atoms to diffuse deep into the silicon wafer;

[0103] S61: Atmosphere switching, close the boron trichloride gas channel, stop the boron source supply, switch the atmosphere in the furnace tube to pure nitrogen, maintain a reducing atmosphere, and prevent boron atoms from being oxidized;

[0104] S62: Temperature control, raise the furnace tube temperature to 900℃ at a rate of 4℃ / min, keep the nitrogen flow rate constant during the temperature rise, and maintain the furnace pressure at 170mbar; after reaching 900℃, stabilize for 30s;

[0105] S63: Propulsion process, maintaining 900℃, pure nitrogen atmosphere, 170mbar pressure, and performing a propulsion process for 750s; the core purpose of the propulsion stage is to promote the deep diffusion of boron atoms into the silicon wafer, eliminate the concentration fluctuations formed during the deposition stage, and make the PN junction depth reach 80-100nm, further improving the sheet resistance uniformity.

[0106] S7: Post-oxidation to prepare a dense BSG layer;

[0107] S71: Atmosphere switching, close the nitrogen channel and switch the atmosphere in the furnace tube to high-purity oxygen;

[0108] S72: Temperature control, the furnace tube temperature is raised to 1000℃ at a rate of 5℃ / min. During the temperature rise, the oxygen flow rate is gradually increased to 28000sccm, and the furnace pressure is simultaneously raised to 900mbar. After reaching 1000℃, the temperature is stabilized for 30 seconds to ensure temperature and pressure stability.

[0109] S73: Post-oxidation treatment, maintaining 1000℃, 28000sccm oxygen, and 900mbar pressure for 4800s post-oxidation treatment; SiO2 adsorbs boron atoms to form BSG, and the combination of high-purity oxygen and high temperature can improve the density of the oxide layer and enhance the passivation effect.

[0110] S8: Back pressure purging and cooling;

[0111] S81: Back pressure control. After the post-oxidation is completed, stop heating, maintain oxygen flow rate of 28000 sccm, and gradually open the exhaust valve to reduce the furnace pressure from 900 mbar to atmospheric pressure to avoid sudden pressure drop that could cause the silicon wafer to crack.

[0112] S82: Nitrogen purging. After the pressure drops to atmospheric pressure, close the oxygen channel and switch to nitrogen supply. Nitrogen flow rate is 15000 sccm. Purge for 300 seconds to remove residual oxygen and corrosive gases such as SiCl4 from the furnace tube, and avoid corrosion of the quartz furnace tube and contamination of the silicon wafer surface.

[0113] S82: Cooling treatment. After the purging is qualified, start the furnace tube cooling program and let it cool naturally to below 300℃. During the cooling process, nitrogen is continuously introduced to maintain a slight positive pressure inside the furnace and prevent air from entering.

[0114] S9: Take the film;

[0115] S91: Wafer removal operation. After the temperature inside the furnace tube drops below 300℃ and the pressure stabilizes at atmospheric pressure, open the furnace door, remove the quartz boat, and use a vacuum pen to remove the silicon wafer from the quartz boat.

[0116] Example 2:

[0117] The theoretical basis is that periodic concentration fluctuations promote uniform diffusion of boron atoms. In traditional continuous gas supply, boron atoms continuously adhere to the silicon wafer surface, which is prone to localized excessive concentration and agglomeration due to gas turbulence and slight temperature fluctuations. In contrast, pulsed gas supply, through periodic cycles of supply and interval, allows boron atoms to adhere to the silicon wafer surface during the supply phase. During the interval phase, no new boron atoms are added, and the already attached boron atoms diffuse freely on the surface, eliminating localized concentration differences and achieving uniform distribution.

[0118] Meanwhile, the phased optimization of the pulse frequency is based on the needs of different stages of boron diffusion. In the pre-deposition stage, a basic doped layer needs to be formed quickly, so a higher pulse frequency is used to shorten the single cycle time and improve the deposition efficiency. In the advancement stage, boron atoms need to be fully penetrated into the interior, so a lower pulse frequency is used to extend the interval time and promote the migration of boron atoms from the surface to the interior.

[0119] By combining an atmosphere segmentation switching strategy, the optimal gas environment is matched in the pre-oxidation, deposition, propulsion, and post-oxidation stages, and works in synergy with pulsed gas supply to further improve the uniformity of boron diffusion and the quality of the oxide layer, while reducing the loss of quartz devices.

[0120] See appendix Figure 1 The equipment in this embodiment is basically the same as that in Embodiment 1, except that a pulse gas supply controller is added, as detailed below:

[0121] S1-S4 in this embodiment are completely identical to those in embodiment 1;

[0122] S5: Boron source deposition is performed using pulsed gas supply and segmented atmosphere switching;

[0123] This step is the core innovation phase, lasting a total of 540 seconds. The furnace pressure is maintained at a constant 170 mbar throughout the process, and the atmospheric environment is as follows:

[0124] O2 / N2 = 1:3

[0125] The boron source concentration was fixed at 0.45 × 10⁻⁶. 20 / cm 3 It adopts a pulsed gas supply mode;

[0126] S51: Temperature control, the furnace tube temperature is raised to 840℃ at a rate of 3℃ / min, the gas flow rate is kept constant during the heating process, and after stabilizing for 20s, the temperature inside the furnace tube is ensured to be uniform; 840℃ is chosen as the deposition temperature because the boron atom diffusion coefficient and adsorption efficiency reach a balance at this temperature. Combined with pulsed gas supply, uniformity and deposition efficiency can be taken into account.

[0127] S52: Pulse parameter setting, start the pulse gas supply controller, set the pulse frequency to 0.5Hz, and each pulse cycle includes 12 seconds of gas supply time and 6 seconds of interval time;

[0128] S53: Pulsed gas supply deposition. The pulsed gas supply program is initiated, simultaneously introducing boron trichloride, oxygen, and nitrogen, maintaining the above parameters for deposition for 540 seconds. During deposition, the boron atom concentration is monitored in real-time using a gas concentration detector to ensure it remains stable at 0.45 × 10⁻⁶. 20 / cm 3 ±5%;

[0129] The principle of this pulsed gas supply is as follows:

[0130] During the gas supply phase, boron atoms continuously adhere to the silicon wafer surface, forming a preliminary doped layer. During the interval phase, the boron source supply is stopped, and the already attached boron atoms diffuse freely on the surface, eliminating areas with excessively high local concentrations and preventing agglomeration. After about 30 cycles (540s), a uniform boron-rich layer is formed.

[0131] S6: Propulsion process to allow boron atoms to diffuse deep into the silicon wafer;

[0132] S61: Atmosphere switching, close the boron trichloride gas channel and stop the boron source supply; switch the atmosphere in the furnace tube to pure nitrogen to maintain a reducing atmosphere and prevent the oxidation of boron atoms;

[0133] S62: Temperature control, raises the furnace tube temperature to 900℃ at a rate of 4℃ / min, stabilizes for 30s, and ensures uniform temperature.

[0134] S63: Pulse parameter adjustment. Adjust the pulse gas supply frequency to 0.2Hz. Each pulse cycle includes 15 seconds of gas supply time and 10 seconds of interval time. The reason for choosing a lower pulse frequency is that the propulsion stage needs to promote the diffusion of boron atoms into the silicon wafer. The longer interval time allows boron atoms enough time to migrate from the surface to the interior, avoiding them from staying on the surface and causing uneven concentration.

[0135] S64: Propulsion process, maintaining 900℃, pure nitrogen atmosphere, 0.2Hz pulse gas supply, and 170mbar pressure, for 750s of propulsion process; during the propulsion process, the sheet resistance at the center of the silicon wafer is tested every 150s, and the sheet resistance change rate is ≤2% / 150s to ensure deep diffusion of boron atoms.

[0136] S7-S9 of this embodiment are completely identical to those of embodiment 1;

[0137] The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described or explained in this invention are implemented according to conventional methods in the art unless otherwise specified or limited.

Claims

1. A method for extending the service life of boron-deposited quartz devices, characterized in that, Includes the following steps: S1: Pre-treatment, RCA standard cleaning of silicon wafers; S2: Wafer loading and furnace tube pretreatment: The cleaned silicon wafers are loaded into a quartz boat and sent into a tube diffusion furnace for nitrogen purging to remove residual air in the furnace tube. S3: Heat up and perform a closed-tube leak test. After stabilization, test the furnace tube sealing performance using nitrogen pressure testing. S4: Pre-oxidation, forming an oxide film layer on the silicon wafer surface; S5: Boron source deposition; S6: Propulsion processing; S7: Post-oxidation to prepare the BSG layer; S8: Back pressure purging and cooling; S9: Take the film.

2. The method for extending the service life of boron-deposited quartz devices according to claim 1, characterized in that: S2 includes: S21: Wafer loading, loading the silicon wafers face up into the quartz boat; S22: Furnace tube pretreatment. The quartz boat is sent into the effective reaction zone of the furnace tube and aligned in the center. After the furnace door is closed, nitrogen gas is introduced for purging.

3. The method for extending the service life of boron-deposited quartz devices according to claim 2, characterized in that: S3 specifically includes: S31: Temperature control, nitrogen gas is introduced during the heating process to maintain the furnace pressure at 150mbar; S32: Temperature is stable, and it remains stable for 30 seconds after reaching 825℃ to ensure a uniform temperature field inside the furnace tube; S33: Closed-pipe leak detection.

4. The method for extending the service life of boron-deposited quartz devices according to claim 3, characterized in that: S4 specifically includes: S41: Atmosphere configuration, adjust the furnace pressure to 170mbar, control the oxygen to nitrogen flow ratio to 1:5 through the gas mixer, mix for 30s to ensure gas uniformity; S42: Pre-oxidation treatment, maintaining 825℃, 170mbar pressure and the above atmosphere, for 300s to form an oxide film with a thickness of 5-8nm on the silicon wafer surface.

5. The method for extending the service life of boron-deposited quartz devices according to claim 4, characterized in that: S5 employs progressive flow control, which includes the following steps: S51: Deposition of low-concentration boron source, maintaining furnace temperature at 825℃ and pressure at 170mbar, introducing oxygen at 400sccm and nitrogen at 1700sccm, stabilizing for 30s, then introducing boron trichloride, and depositing for 180s. S52: Deposition of medium-concentration boron source, heating to 835℃ at a rate of 3℃ / min and stabilizing for 20s, maintaining constant gas flow rate, deposition for 180s; S53: High-concentration boron source deposition, heating to 845℃ at a rate of 3℃ / min and stabilizing for 20s, maintaining the above gas environment, deposition for 180s, so that the boron atom penetration depth reaches 50-60nm, forming a PN junction.

6. The method for extending the service life of boron-deposited quartz devices according to claim 5, characterized in that: S6 specifically includes: S61: Atmosphere switching, close the boron source channel, and switch to a pure nitrogen reducing atmosphere; S62: Temperature control, heating to 900℃ at a rate of 4℃ / min and stabilizing for 30s, maintaining furnace pressure of 170mbar and stable nitrogen flow rate; S63: Propulsion processing, maintaining 900℃, pure nitrogen atmosphere and 170mbar pressure, processing for 750s, to achieve a PN junction depth of 80-100nm.

7. The method for extending the service life of boron-deposited quartz devices according to claim 6, characterized in that: Specifically, S7 includes: S71: Atmosphere switching, close the nitrogen channel and switch to high-purity oxygen; S72: Temperature control, heating to 1000℃ at a rate of 5℃ / min and stabilizing for 30s, while simultaneously increasing the oxygen flow rate to 28000sccm and the furnace pressure to 900mbar; S73: Post-oxidation treatment, maintaining the above temperature, pressure and oxygen flow rate, for 4800s.

8. The method for extending the service life of boron-deposited quartz devices according to claim 7, characterized in that: S8 specifically includes: S81: Back pressure control, stop heating, maintain oxygen flow rate of 28000sccm, and gradually reduce pressure to atmospheric pressure; S82: Nitrogen purging, switch to nitrogen supply, purge for 300 seconds to remove residual gas; S83: Cooling treatment, nitrogen gas is continuously introduced to maintain a slight positive pressure inside the furnace, and the temperature is naturally reduced to below 300℃.

9. A method for extending the service life of boron-deposited quartz devices according to claim 4, characterized in that: S5 employs pulsed gas supply control, and the tubular diffusion furnace is equipped with a pulsed gas supply controller. Step S5 specifically includes the following steps: S51: Temperature control, heating to 840℃ at a rate of 3℃ / min and stabilizing for 20s to ensure uniform temperature inside the furnace; S52: Pulse parameter setting, start the pulse air supply controller, set the pulse frequency to 0.5Hz, and each pulse cycle includes 12 seconds of air supply time and 6 seconds of interval time; S53: Pulse gas supply deposition, oxygen, nitrogen and high-purity boron trichloride are introduced, furnace pressure is maintained at 170 mbar, deposition time is 540 s, and a uniform boron-rich layer is formed.

10. A method for extending the service life of boron-deposited quartz devices according to claim 7, characterized in that: S6 specifically includes: S61: Atmosphere switching, close the boron source channel, and switch to a pure nitrogen reducing atmosphere; S62: Temperature control, heating to 900℃ at a rate of 4℃ / min and stabilizing for 30s, maintaining furnace pressure of 170mbar and stable nitrogen flow rate; S63: Adjust the pulse gas supply frequency to 0.2Hz, with each pulse cycle including 15 seconds of gas supply time and 10 seconds of interval time.

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