Method for synchronously checking pollution of LPCVD (Low Pressure Chemical Vapor Deposition) pipe and phosphorus diffusion pipe
By cascading the LPCVD deposition and phosphorus diffusion process chain and designing baffles, combined with a minority carrier lifetime tester, efficient and accurate source tracing of LPCVD and phosphorus diffusion tube contamination was achieved, solving the problem of cumbersome and time-consuming detection in existing technologies and improving the production efficiency and yield of crystalline silicon solar cells.
Patent Information
- Application Number
- CN202511174656.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-21
- Publication Date
- 2025-11-28
AI Technical Summary
In the production of crystalline silicon solar cells, existing technologies involve cumbersome and time-consuming contamination detection of LPCVD tubes and phosphorus diffusion tubes, resulting in production line downtime losses and low efficiency. Furthermore, the single furnace tube inspection method requires repeated testing, which prolongs the inspection cycle.
A series of LPCVD deposition and phosphorus diffusion processes are adopted. By continuously inserting silicon wafers and using a baffle design, a correspondence between silicon wafers and furnace tubes is established. Simultaneous contamination detection is performed using a WCT-120 minority carrier lifetime tester to track contamination sources.
It enables rapid and accurate identification of pollution sources, reduces investigation cycles, lowers testing costs, increases production capacity and equipment utilization, and ensures film uniformity and doping effect.
Smart Images
Figure CN121034985A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of solar cell technology, specifically to a method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes. Background Technology
[0002] Crystalline silicon solar cells have long dominated the photovoltaic cell market due to readily available raw materials, mature manufacturing technology, reliable performance, and relatively low cost. In the mass production of crystalline silicon solar cells, especially TOPCon cells, LPCVD (low-pressure chemical vapor deposition) and phosphorus diffusion processes are the core process chain for forming passivated contact structures, and the cleanliness of their equipment directly affects cell efficiency and yield. However, the hundreds of LPCVD tubes and phosphorus diffusion tubes configured in large-scale production lines face multiple contamination risks during continuous operation: dust from the workshop environment, residual dirt in gas pipelines, contaminants carried by silicon wafers after alkaline polishing, and dust accumulated on the tube walls can all enter the reaction chamber with the process gas. As the process cycle lengthens, these contaminants settle on the silicon wafer surface, leading to deterioration of film uniformity, increased cell leakage rate, decreased open-circuit voltage, and reduced cell efficiency and yield. However, since the cleanliness quality of the furnace tubes cannot be directly and accurately obtained, a large amount of manpower, numerous silicon wafer verifications, and a lengthy inspection cycle are required.
[0003] Currently available contamination detection technologies mainly include: 1. Traditional "carpet-style search," which requires inserting test wafers into each LPCVD tube or phosphorus diffusion tube individually for inspection. This tedious inspection and verification process, along with the tracking of numerous experiments, wastes manpower and resources. Moreover, prolonged shutdowns or production with defects in abnormal production lines can easily lead to consistently low yields and efficiency, resulting in significant economic losses for the production line. 2. Single furnace tube inspection method: While methods for rapid inspection of individual furnace tubes exist, in reality, silicon wafer contamination may originate from furnace tubes in upstream or downstream processes. Therefore, repeated rounds of cyclical testing are required to pinpoint the source of contamination, leading to prolonged inspection cycles and severe capacity losses. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides a method for simultaneous contamination detection of LPCVD tubes and phosphorus diffusion tubes. By connecting the LPCVD deposition and phosphorus diffusion process chains in series, contamination detection of both types of furnace tubes can be completed simultaneously in a single process.
[0005] The present invention adopts the following technical solution:
[0006] This invention discloses a method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes, comprising the following steps:
[0007] S1, Silicon wafer pretreatment: Take a certain number of silicon wafers for texturing, cleaning, and alkaline polishing;
[0008] S2, take the above silicon wafers and insert m wafers (m≥1) continuously into the LPCVD boat, and send each LPCVD boat into a different LPCVD tube for deposition process.
[0009] S3, remove all the silicon wafers from each of the above LPCVD boats, and then insert n wafers (n≥1) into the phosphorus diffusion boats one by one. Send each phosphorus diffusion boat into different phosphorus diffusion tubes for phosphorus diffusion process, and the silicon wafers deposited in the same LPCVD tube enter at least two phosphorus diffusion tubes for diffusion.
[0010] S4. Collect the silicon wafers mentioned above, test each silicon wafer separately, and record the test results;
[0011] S5. Determine the above test results and track the contaminated furnace tubes based on whether the determination results are abnormal.
[0012] Furthermore, the silicon wafers inserted into the LPCVD boat and the phosphorus diffusion boat have baffles at both ends and a test wafer in the middle. The number of silicon wafers inserted into the LPCVD boat is m≥3 and the number of silicon wafers inserted into the phosphorus diffusion boat is n≥3, and neither exceeds the maximum number of wafers that the boat can carry. The number of silicon wafers in the LPCVD boat and the phosphorus diffusion boat may be the same or different.
[0013] Furthermore, the number of test pieces inserted into the LPCVD and phosphorus diffusion boat is 3-18 pieces.
[0014] The purpose of the baffle is to accurately simulate the silicon wafer loading state under mass production conditions and to physically constrain the airflow and reaction behavior at the edge of the test wafer. Without the baffle, the edge of the test wafer forms an abnormal airflow channel due to the lack of shielding by adjacent silicon wafers, which leads to an increase in local gas velocity and thinning of the boundary layer, causing an abnormally high deposition / diffusion reaction rate and masking the film unevenness or doping abnormality caused by actual contamination. The baffle eliminates the false data deviation caused by such edge effects and ensures that the contamination detection results are comparable to those in mass production.
[0015] Furthermore, the silicon wafer was tested using a WCT-120 minority carrier lifetime tester.
[0016] Furthermore, the silicon wafer is tested using at least one of the following methods: virtual open-circuit voltage (iVoc), minority carrier lifetime, virtual fill factor (FF), and photoluminescence (PL) testing.
[0017] Furthermore, the criteria for judging the test results are as follows:
[0018] If the virtual open-circuit voltage test value is ≤700mV, the silicon wafer is abnormal; and / or,
[0019] If the minority carrier lifetime test value is ≤1000μs, the silicon wafer is abnormal; and / or,
[0020] If the virtual fill factor test value is ≤85%, the silicon wafer is abnormal; and / or,
[0021] If the photoluminescence test result image contains black dark areas or white bright areas, and the contrast with the background grayscale is obvious, then the silicon wafer is abnormal.
[0022] Furthermore, the method for tracing contaminated furnace tubes is as follows:
[0023] a. If the test results show that all test pieces are normal, then the LPCVD tube and the phosphorus diffusion tube are all normal.
[0024] b. If the test results show an abnormal test piece: track the status of other test pieces in the same phosphorus diffusion tube that this test piece passed through;
[0025] b1. If the test piece passing through this phosphorus diffusion tube is abnormal, then trace the LPCVD tube through which the abnormal test piece passed, and the contaminated furnace tube is the corresponding LPCVD tube.
[0026] b2. If all test pieces at the same position in this phosphorus diffusion tube are abnormal, first track the other test pieces in the same LPCVD tube that the abnormal test pieces passed through. If some are abnormal, then the contaminated furnace tube is this phosphorus diffusion tube. If all test pieces in the same LPCVD tube are abnormal, then take a verified normal test piece and send it into this phosphorus diffusion tube for retesting. If the test result is normal, then all LPCVD tubes that the test piece passed through are contaminated. If the test result is abnormal, then both the phosphorus diffusion tube and the LPCVD tube that the test piece passed through are contaminated.
[0027] Furthermore, when the investigation method detects specific contamination sites in the furnace tube, the LPCVD boat is sent into the furnace opening, furnace middle and furnace tail positions of the LPCVD tube respectively. Then, the silicon wafer is taken out and inserted into the phosphorus diffusion boat, and sent into the furnace opening, furnace middle and furnace tail positions of the phosphorus diffusion tube respectively for phosphorus diffusion process. After the silicon wafer is tested, the specific contamination sites of the furnace tube can be further traced.
[0028] Furthermore, the aforementioned investigation method is applicable to the investigation of contamination in LPCVD tubes and phosphorus diffusion tubes during the production process of solar cells.
[0029] The method for simultaneous contamination detection of LPCVD tubes and phosphorus diffusion tubes according to the present invention has the following beneficial effects:
[0030] 1. By sequentially depositing silicon wafers in the same batch through LPCVD tubes and doping them through phosphorus diffusion tubes, and recording the process path of each silicon wafer, a complete chain of correspondence between silicon wafers and furnace tubes was constructed. When test results are abnormal, the specific contaminated furnace tube can be directly traced, completing the contamination screening of both LPCVD tubes and phosphorus diffusion tubes in one go, avoiding the extended downtime caused by traditional step-by-step investigation.
[0031] 2. This invention adopts a strategy of continuous single-insertion silicon wafer distribution and series process, which requires only a small number of silicon wafers to cover multiple process tube combinations, reducing testing costs; the baffle design simulates the loading density of mass-produced silicon wafers, eliminates airflow disturbances and abnormal reactions at the edge of the silicon wafer, ensures that the test data truly reflects the uniformity of the film layer and the doping effect under mass production environment, and avoids false data interference caused by edge effects.
[0032] 3. This invention uses a stratified judgment system to accurately locate pollution sources, enabling rapid identification of pollution sources, reducing investigation cycles, and increasing production capacity. Simultaneously, it verifies through retesting steps, resolving blind spots caused by cross-contamination. The LPCVD / phosphorus tube expansion is divided into three sections: furnace inlet, furnace middle, and furnace tail. A small boat is then inserted into each of these three sections to further trace the specific contamination location within the furnace tube.
[0033] In summary, this invention enables efficient and precise source tracing of contamination in core equipment such as LPCVD furnace tubes and phosphorus diffusion furnace tubes, significantly improving production line yield and equipment utilization, and providing core technical support for the large-scale production of crystalline silicon solar cells. Attached Figure Description
[0034] To more clearly illustrate the technical solutions of the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is a flowchart illustrating the method for simultaneously investigating LPCVD and phosphorus diffusion tube contamination according to an embodiment of the present invention.
[0036] Figure 2 This is a schematic diagram of a method for tracing contaminated furnace tubes when simultaneously investigating LPCVD and phosphorus diffusion tube contamination, as provided in an embodiment of the present invention.
[0037] Figure 3 This is a graph showing the PL test results of a normal silicon wafer in Embodiment 2 of the present invention.
[0038] Figure 4 This is a graph showing the PL test results of the abnormal silicon wafer in Embodiment 2 of the present invention. Detailed Implementation
[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.
[0040] Example 1: Simultaneous Investigation Method for Contamination of LPCVD Tubes and Phosphorus Diffusion Tubes
[0041] This embodiment provides a method for simultaneously investigating LPCVD and phosphorus expansion tube contamination, such as... Figure 1 As shown, the method specifically includes the following steps:
[0042] S1, silicon wafer pretreatment: Take 10 silicon wafers for texturing, cleaning, and alkaline polishing for later use. Take another 10 silicon wafers as baffles. The baffles are reused in the LPCVD and phosphorus diffusion processes.
[0043] S2, take the pretreated silicon wafers mentioned above and insert two silicon wafers into each LPCVD boat as test wafers. Insert one baffle at each end of the test wafer. Prepare five identical LPCVD boats in the same way and send the five LPCVD boats into five LPCVD tubes for deposition process.
[0044] S3, after removing all the test pieces from the above LPCVD boats, insert one piece into each of the five phosphorus diffusion boats, and insert a baffle into each end of the test piece in each phosphorus diffusion boat. Then, send the five phosphorus diffusion boats into the five phosphorus diffusion tubes respectively.
[0045] S4. Collect the above test pieces, test the test pieces using the WCT-120 minority carrier lifetime tester, and record the test results;
[0046] S5, make a judgment on the above test results, and trace the contaminated furnace tubes based on the judgment results.
[0047] The test strip path allocation table is shown in Table 1. Each LPCVD and phosphorus diffusion tube has been repeatedly verified by two test strips.
[0048] Table 1 Test Component Path Allocation Table
[0049]
[0050] Note: Numbers 1-10 in the table represent test piece serial numbers.
[0051] Table 2 Test Results of Test Pieces
[0052]
[0053] The test results are shown in Table 2. The same batch of silicon wafers in this invention underwent sequential LPCVD tube deposition and phosphorus diffusion tube doping, enabling simultaneous screening of LPCVD tube and phosphorus diffusion tube contamination. By comparing the differences in test results between different furnace tubes, the source of contamination could be effectively identified, significantly improving screening efficiency and simultaneously completing the screening of contamination status for multiple furnace tubes. As shown in Table 2, all test wafers were normal and passed the test. Figure 2 The method for tracing contaminated furnace tubes showed that both LPCVD tubes 1-5 and phosphorus diffusion tubes 1-5 were normal, clean furnace tubes.
[0054] Example 2: Simultaneous Investigation Method for Contamination of LPCVD Tubes and Phosphorus Diffusion Tubes
[0055] This embodiment provides a method for simultaneously investigating LPCVD and phosphorus expansion tube contamination, such as... Figure 1 As shown, the method specifically includes the following steps:
[0056] S1, silicon wafer pretreatment: Take 10 silicon wafers for texturing, cleaning, and alkaline polishing for later use. Take another 10 silicon wafers as baffles. The baffles are reused in the LPCVD and phosphorus diffusion processes.
[0057] S2, take the pretreated silicon wafers mentioned above and insert two silicon wafers into each LPCVD boat as test wafers. Insert one baffle at each end of the test wafer. Prepare five identical LPCVD boats in the same way and send the five LPCVD boats into five LPCVD tubes for deposition process.
[0058] S3, after removing all the test pieces from the above LPCVD boats, insert one piece into each of the five phosphorus diffusion boats, and insert a baffle into each end of the test piece in each phosphorus diffusion boat. Then, send the five phosphorus diffusion boats into the five phosphorus diffusion tubes respectively.
[0059] S4. Collect the above test pieces, test the test pieces using the WCT-120 minority carrier lifetime tester, and record the test results;
[0060] S5, make a judgment on the above test results, and trace the contaminated furnace tubes based on the judgment results.
[0061] The test strip path allocation table is shown in Table 3. Each LPCVD and phosphorus diffusion tube shown has been repeatedly verified by two test strips.
[0062] Table 3 Test Component Path Allocation Table
[0063]
[0064] Note: Numbers 1-10 in the table represent test piece serial numbers.
[0065] Table 4 Test Results of Test Pieces
[0066]
[0067] The test results are shown in Table 4. The results show that test pieces 8 and 9 are abnormal. Figure 3 The image shown is a graph of the PL test results for test piece #1 (normal test piece). Figure 4 The image shown is a graph illustrating the PL test results for test piece #8, which exhibited abnormality. Figure 2 The method for tracing contaminated furnace tubes involves first checking the test results of other test pieces in phosphorus diffusion tube 5, which are passed through by test pieces 8 and 9. If all test pieces in phosphorus diffusion tube 5 are found to be abnormal (test pieces 8 and 9), then further investigation is conducted on the test pieces in the LPCVD tubes (LPCVD4 and LPCVD5) that test pieces 8 and 9 have passed through. If the test pieces (test pieces 7 and 10) are found to be normal, then LPCVD4 and LPCVD5 are not the problem, and phosphorus diffusion tube 5 is contaminated.
[0068] Example 3: Simultaneous Investigation Method for Contamination of LPCVD Tubes and Phosphorus Diffusion Tubes
[0069] This embodiment provides a method for simultaneously investigating LPCVD and phosphorus expansion tube contamination, detecting specific contamination sites in the furnace tube. The method specifically includes the following steps:
[0070] S1, silicon wafer pretreatment: 27 silicon wafers are texturized, cleaned, and alkaline polished for later use. Another 18 silicon wafers are used as baffles, which are reused in the LPCVD and phosphorus diffusion processes.
[0071] S2, take the pre-treated silicon wafers and insert 3 silicon wafers into the LPCVD boat as test wafers. Insert 1 baffle at each end of the test wafer. Prepare 9 identical LPCVD boats in the same way. Send the 9 LPCVD boats into the furnace mouth, furnace middle and furnace tail of 3 LPCVD tubes respectively for deposition process.
[0072] S3, after removing all the test pieces from each of the above LPCVD boats, insert 3 pieces into each of the 9 phosphorus diffusion boats. Insert the three test pieces from the same LPCVD boat into 3 different phosphorus diffusion boats. At the same time, insert a baffle into each end of the test piece in each phosphorus diffusion boat. Send the 9 phosphorus diffusion boats into the 3 phosphorus diffusion tubes at the furnace mouth, furnace middle and furnace tail positions for diffusion process.
[0073] S4. Collect the above test pieces, test the test pieces using the WCT-120 minority carrier lifetime tester, and record the test results;
[0074] S5, make a judgment on the above test results, and trace the contaminated furnace tubes based on the judgment results.
[0075] The test piece path allocation table is shown in Table 5. The positions of each LPCVD and phosphorus diffusion tube at the furnace inlet, furnace middle, and furnace tail have been verified by repeated testing with three test pieces.
[0076] Table 5 Test Component Path Allocation Table
[0077]
[0078] Note: Numbers 1-27 in the table represent test piece serial numbers.
[0079] Table 6 Test results for simultaneous investigation of LPCVD and phosphorus diffusion tube contamination
[0080]
[0081] The test results are shown in Table 6. A total of three abnormal test pieces were found: test pieces 3, 12, and 21. According to... Figure 2 The method for tracing contaminated furnace tubes, as shown, first checks the test results of other test tubes (test tubes 1 and 2) at the furnace inlet of phosphorus diffusion tube 1, which is traversed by test tube 3. Only test tube 3 is found to be abnormal; therefore, the furnace inlet of LPCVD3 traversed by test tube 3 is contaminated. Similarly, tracing abnormal test tube 12, all other test tubes at the furnace inlet of phosphorus diffusion tube 2 are normal; therefore, the furnace inlet of LPCVD3 traversed by test tube 12 is contaminated. Tracing abnormal test tube 21, all other test tubes at the furnace inlet of phosphorus diffusion tube 3 are normal; therefore, the furnace inlet of LPCVD3 traversed by test tube 21 is contaminated.
[0082] Example 4: Simultaneous Investigation Method for Contamination of LPCVD Tubes and Phosphorus Diffusion Tubes
[0083] This embodiment provides a method for simultaneously investigating LPCVD and phosphorus expansion tube contamination, detecting specific contamination sites in the furnace tube. The method specifically includes the following steps:
[0084] S1, silicon wafer pretreatment: 27 silicon wafers are texturized, cleaned, and alkaline polished for later use. Another 18 silicon wafers are used as baffles, which are reused in the LPCVD and phosphorus diffusion processes.
[0085] S2, take the pre-treated silicon wafers and insert 3 silicon wafers into the LPCVD boat as test wafers. Insert 1 baffle at each end of the test wafer. Prepare 9 identical LPCVD boats in the same way. Send the 9 LPCVD boats into the furnace mouth, furnace middle and furnace tail of 3 LPCVD tubes respectively for deposition process.
[0086] S3, after removing all the test pieces from each of the above LPCVD boats, insert 3 pieces into each of the 9 phosphorus diffusion boats. Insert the three test pieces from the same LPCVD boat into 3 different phosphorus diffusion boats. At the same time, insert a baffle into each end of the test piece in each phosphorus diffusion boat. Send the 9 phosphorus diffusion boats into the 3 phosphorus diffusion tubes at the furnace mouth, furnace middle and furnace tail positions for diffusion process.
[0087] S4. Collect the above test pieces, test the test pieces using the WCT-120 minority carrier lifetime tester, and record the test results;
[0088] S5, make a judgment on the above test results, and trace the contaminated furnace tubes based on the judgment results.
[0089] The test piece path allocation table is shown in Table 7. The positions of each LPCVD and phosphorus diffusion tube at the furnace inlet, furnace middle, and furnace tail have been verified by repeated testing with three test pieces.
[0090] Table 7 Test Component Path Allocation Table
[0091]
[0092] Note: Numbers 1-27 in the table represent test piece serial numbers.
[0093] Table 8 Test results for simultaneous investigation of LPCVD and phosphorus diffusion tube contamination.
[0094]
[0095] The test results are shown in Table 8. A total of 5 abnormal test pieces were found, namely test pieces 2, 11, 19, 20 and 21. According to... Figure 2 The method shown is to trace contaminated furnace tubes. First, check the test results of other test tubes (test tubes 1 and 3) at the furnace mouth position of phosphorus diffusion tube 1 that test tube 2 passes through. It was found that only test tube 2 was abnormal. Therefore, the furnace mouth position of LPCVD2 that test tube 2 passes through is contaminated.
[0096] Similarly, when the abnormal test piece 11 was traced, the other test pieces (test pieces 10 and 12) at the furnace mouth of the phosphorus diffusion tube 2 it passed through were all normal. Therefore, the contamination was at the furnace mouth of LPCVD2 that the test piece 11 passed through.
[0097] The abnormal test wafer 19 was traced, and all other test wafers at the furnace opening of the phosphorus diffusion tube 3 were abnormal (test wafers 19, 20, and 21). The situation of other test wafers at the furnace opening of LPCVD1 that silicon wafer 19 passed through was traced, and it was found that only test wafer 19 was abnormal. Therefore, it was determined that the contamination was at the furnace opening of the phosphorus diffusion tube 3.
[0098] The abnormal test wafer No. 20 was traced, and all other test wafers at the LPCVD2 furnace opening position that it passed through were abnormal (test wafers No. 19, 20, and 21). The situation of other test wafers at the LPCVD2 furnace opening position that silicon wafer No. 20 passed through was also traced, and all of them were found to be abnormal (test wafers No. 2, 11, and 20). Test wafers that had been deposited in the LPCVD3 furnace position were taken (it was verified that the LPCVD3 furnace position was clean, so the test wafers taken for retesting were normal), and sent to the LPCVD2 furnace opening position for retesting. The retest results showed abnormality, so it was determined that both the LPCVD2 furnace opening position and the LPCVD2 furnace opening position were contaminated.
[0099] The abnormal test wafer 21 was traced, and all other test wafers at the furnace opening of the phosphorus diffusion tube 3 were abnormal (test wafers 19, 20, and 21). The situation of other test wafers at the furnace opening of LPCVD2 that silicon wafer 21 passed through was traced, and it was found that only test wafer 21 was abnormal. Therefore, it was determined that the contamination was at the furnace opening of the phosphorus diffusion tube 3.
[0100] Comparative Example 1: Method for troubleshooting LPCVD pipe contamination separately
[0101] A method for investigating LPCVD pipe contamination, the method specifically includes the following steps:
[0102] S1, Silicon wafer pretreatment: Take silicon wafers for double-sided texturing, cleaning, and double-sided alkaline polishing;
[0103] S2, the silicon wafers mentioned above are continuously inserted into the LPCVD boat, including the middle test wafer and two baffles at both ends. The LPCVD boat is then sent to the furnace opening, furnace middle and furnace tail positions of each LPCVD tube for deposition.
[0104] S3, take out all the test pieces from each of the above LPCVD boats, insert them one by one into the phosphorus diffusion boat, and then insert two baffles at the top and bottom. Select the tubes that have no abnormalities in the phosphorus diffusion process operation records and SPC, and send them into the same position in the same phosphorus diffusion tube to carry out the phosphorus diffusion process.
[0105] S4. Collect the above test pieces, use the WCT-120 minority carrier lifetime tester to test them, and record the test results.
[0106] S5, judge the above test results, the LPCVD tube through which the abnormal test piece passed is the contaminated furnace tube;
[0107] Comparative Example 2: Method for investigating phosphorus diffusion pipe contamination separately
[0108] A method for investigating phosphorus diffusion tube contamination, the method specifically includes the following steps:
[0109] S1, Silicon wafer pretreatment: Take silicon wafers for double-sided texturing, cleaning, and double-sided alkaline polishing;
[0110] S2, insert the silicon wafer into the LPCVD boat, select the tube with no abnormalities in the LPCVD process operation record and SPC, and send the LPCVD boat into the same position in the LPCVD tube to perform the deposition process.
[0111] S3, take out all the test pieces from each of the above LPCVD boats, insert them one by one into the phosphorus diffusion boat, and then insert two baffles on the outermost side of all the test pieces, and send them into the positions of the furnace mouth, furnace and furnace tail of each phosphorus diffusion tube for phosphorus diffusion process.
[0112] S4. Collect the above test pieces, use the WCT-120 minority carrier lifetime tester to test them, and record the test results.
[0113] S5. Determine the above test results. The phosphorus diffusion tube through which the abnormal test piece passed is the contaminated furnace tube.
[0114] As can be seen from Examples 1-4 and Comparative Examples 1-2, this invention discloses a method for simultaneous contamination screening of LPCVD tubes and phosphorus diffusion tubes. By sequentially depositing silicon wafers in the same batch through LPCVD tubes and doping through phosphorus diffusion tubes, and recording the process path of each silicon wafer, a complete correspondence chain between silicon wafers and furnace tubes is constructed. When the test results are abnormal, the specific contaminated furnace tube can be directly traced, completing the contamination screening of both LPCVD tubes and phosphorus diffusion tubes in one go. This avoids the prolonged downtime caused by traditional step-by-step screening, significantly improving screening efficiency. It is suitable for multi-tube parallel production scenarios and can simultaneously screen the contamination status of multiple furnace tubes.
[0115] As can be seen from the comparison of Examples 1 and 2, and Comparative Examples 1 and 2, the simultaneous screening method for LPCVD tube and phosphorus diffusion tube contamination in this invention requires only 10 test pieces to achieve repeated verification of each furnace tube twice when screening 5 LPCVD tubes and 5 phosphorus diffusion tubes. However, as shown by the methods in Comparative Examples 1 and 2, when using separate screening methods, 10 test pieces are needed for each of the 5 LPCVD tubes and 5 phosphorus diffusion tubes to achieve repeated verification of each furnace tube twice, meaning a total of 20 test pieces are needed to achieve the screening effect of Example 1 in this invention. As can be seen from the comparison of Examples 3 and 4, and Comparative Examples 1 and 2, the detection of contamination in the furnace tubes... When identifying specific contamination locations, Example 2 requires only 27 test wafers to complete the inspection of three locations—the furnace inlet, furnace middle, and furnace tail—for three LPCVD furnace tubes and three phosphorus diffusion tubes. Furthermore, the furnace inlet, furnace middle, and furnace tail locations for each LPCVD and phosphorus diffusion tube are repeatedly verified using three test wafers. In contrast, the individual inspection methods in Comparative Examples 1 and 2 require 54 wafers to achieve the same effect as Example 2. The inspection method of this invention reduces the number of test wafers by 50%, requiring only a small number of silicon wafers to cover multiple process tube combinations, thus reducing testing costs. It completes contamination screening for both LPCVD and phosphorus diffusion tubes in one go, avoiding the problems of long inspection times, high costs, and resulting production capacity and yield losses caused by traditional step-by-step inspections.
[0116] In summary, this invention enables efficient and precise source tracing of contamination in core equipment such as LPCVD furnace tubes and phosphorus diffusion furnace tubes, significantly improving production line yield and equipment utilization, and providing core technical support for the large-scale production of crystalline silicon solar cells.
[0117] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the nature and scope of the present invention. Various modifications made to the above embodiments by those skilled in the art after reading this specification are all within the scope of protection of the present invention.
Claims
1. A method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes, characterized in that, Includes the following steps: S1, Silicon wafer pretreatment: Take a certain number of silicon wafers for texturing, cleaning, and alkaline polishing; S2, take the above silicon wafers and insert m wafers (m≥1) continuously into the LPCVD boat, and send each LPCVD boat into a different LPCVD tube for deposition process. S3, remove all the silicon wafers from each of the above LPCVD boats, and then insert n wafers (n≥1) into the phosphorus diffusion boats one by one. Send each phosphorus diffusion boat into different phosphorus diffusion tubes for phosphorus diffusion process, and the silicon wafers deposited in the same LPCVD tube enter at least two phosphorus diffusion tubes for diffusion. S4. Collect the silicon wafers mentioned above, test each silicon wafer separately, and record the test results; S5. Determine the above test results and track the contaminated furnace tubes based on whether the determination results are abnormal.
2. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to claim 1, characterized in that, The silicon wafers inserted into the LPCVD boat and the phosphorus diffusion boat are baffles at both ends and the middle silicon wafer is a test wafer. The number of silicon wafers inserted into the LPCVD boat is m≥3 and the number of silicon wafers inserted into the phosphorus diffusion boat is n≥3, and neither exceeds the maximum number of wafers that the boat can carry. The number of silicon wafers in the LPCVD boat and the phosphorus diffusion boat may be the same or different.
3. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to claim 1, characterized in that, The silicon wafer is tested using at least one of the following methods: virtual open-circuit voltage, minority carrier lifetime, virtual fill factor, and photoluminescence testing.
4. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to claim 1, characterized in that, The criteria for judging the test results are as follows: If the virtual open-circuit voltage test value is ≤700mV, the silicon wafer is abnormal; and / or, If the minority carrier lifetime test value is ≤1000μs, the silicon wafer is abnormal; and / or, If the virtual fill factor test value is ≤85%, the silicon wafer is abnormal; and / or, If the photoluminescence test result image contains black dark areas or white bright areas, and the contrast with the background grayscale is obvious, then the silicon wafer is abnormal.
5. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to claim 1, characterized in that, The method for tracing contaminated furnace tubes is as follows: a. If the test results show that all test pieces are normal, then the LPCVD tube and the phosphorus diffusion tube are all normal. b. If the test results show an abnormal test piece: track the status of other test pieces in the same phosphorus diffusion tube that this test piece passed through; b1. If the test piece passing through this phosphorus diffusion tube is abnormal, then trace the LPCVD tube through which the abnormal test piece passed, and the contaminated furnace tube is the corresponding LPCVD tube. b2. If all test pieces passing through this phosphorus diffusion tube are abnormal, first track the other test pieces that the abnormal test pieces passed through in the same LPCVD tube. If some are abnormal, then the contaminated furnace tube is this phosphorus diffusion tube. If all test pieces in the same LPCVD tube are abnormal, then take a verified normal test piece and send it into this phosphorus diffusion tube for retesting. If the test result is normal, then the LPCVD tube that the test piece passed through is contaminated. If the test result is abnormal, then both the phosphorus diffusion tube and the LPCVD tube that the test piece passed through are contaminated.
6. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to claim 1, characterized in that, When the aforementioned investigation method detects specific contamination sites in the furnace tube, the LPCVD boat is sent into the furnace opening, furnace middle, and furnace tail positions of the LPCVD tube, respectively. Then, the silicon wafer is taken out and inserted into the phosphorus diffusion boat, and sent into the phosphorus diffusion tube at the furnace opening, furnace middle, and furnace tail positions for phosphorus diffusion process. After the silicon wafer is tested, the specific contamination sites of the furnace tube can be further traced.
7. The method for simultaneous investigation of contamination in LPCVD tubes and phosphorus diffusion tubes according to any one of claims 1-6, characterized in that, The method is applicable to the investigation of contamination in LPCVD tubes and phosphorus diffusion tubes during the production process of solar cells.