Diffusion method of shingled solar cell and shingled solar cell

Abstract

The present application is applicable to the field of solar cell technology, and provides a diffusion method of a shingled solar cell and a shingled solar cell. The diffusion method of the shingled solar cell comprises: when the resistivity of the silicon wafer is greater than or equal to a preset resistivity threshold, the silicon wafer after phosphorus deposition treatment is subjected to a first preset number of advancement treatments; when the resistivity of the silicon wafer is less than the preset resistivity threshold, the silicon wafer after phosphorus deposition treatment is subjected to a second preset number of advancement treatments. In this way, the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers can be specifically improved, thereby improving the photoelectric conversion efficiency of the shingled solar cell.

Description

Technical Field

[0001] The present application belongs to the technical field of solar cells, and in particular to a diffusion method of a shingled solar cell and a shingled solar cell. Background Art

[0002] The shingled solar cell module is a single large-area cell cut into multiple small-area cells, and then the edge positive electrode of each small cell is bonded to the edge back electrode of the adjacent small cell to form a string. This layout method avoids the blank gap between cells and improves the packaging density and power density of the module. The operating current of the shingled solar cell module is only one-Nth of that before cutting, but the operating voltage increases to N times that before cutting. The increase in operating voltage brings the risk of cell PN junction breakdown or increased leakage current.

[0003] The resistivity range of silicon wafers used in shingled solar cells in the related art is too wide, resulting in insufficient breakdown voltage of cells made from some silicon wafers. Moreover, the PN junction of the battery in the related art is shallow, and the metal in the slurry will penetrate into the PN junction during sintering, causing the risk of leakage of the PN junction. When the operating voltage of the shingled solar cell module is increased, the risk of leakage will further increase, and the risk of PN junction breakdown will also further increase.

[0004] Based on this, how to diffuse silicon wafers to increase the PN junction depth and breakdown voltage of shingled solar cells has become an urgent problem to be solved. Summary of the invention

[0005] The present application provides a diffusion method for a shingled solar cell and a shingled solar cell, aiming to solve the problem of how to perform diffusion processing on a silicon wafer to increase the PN junction depth and breakdown voltage of the shingled solar cell.

[0006] In a first aspect, the diffusion method of the shingled solar cell provided by the present application performs a first preset number of push-in treatments on the silicon wafer after phosphorus deposition treatment when the resistivity of the silicon wafer is greater than or equal to a preset resistivity threshold;

[0007] When the resistivity of the silicon wafer is less than the preset resistivity threshold, the silicon wafer after the phosphorus deposition process is subjected to a second preset number of push-in processes.

[0008] Optionally, the preset resistivity threshold is in the range of 0.6Ω·cm-0.8Ω·cm.

[0009] Optionally, the preset resistivity threshold is 0.7Ω·cm.

[0010] Optionally, the first preset number of times is 1, and the second preset number of times is 2.

[0011] Optionally, the step of performing one or the first push-in treatment on the silicon wafer after the phosphorus deposition treatment is specifically:

[0012] Turn off the phosphorus source;

[0013] Continue to introduce oxygen and nitrogen into the diffusion device and heat the silicon wafer;

[0014] Stopping the introduction of oxygen into the diffusion device and continuing to heat up the silicon wafer;

[0015] The silicon wafer is pushed forward at a constant temperature.

[0016] Optionally, the step of performing a second push-in process on the silicon wafer based on the first push-in process is specifically:

[0017] The silicon wafer is heated up again;

[0018] The silicon wafer is again pushed forward at a constant temperature.

[0019] Optionally, while continuing to introduce oxygen and nitrogen into the diffusion device and heating the silicon wafer:

[0020] The flow rate of nitrogen is in the range of greater than or equal to 1800 sccm;

[0021] The flow rate of oxygen is in the range of greater than or equal to 650 sccm;

[0022] The range of heating rate is greater than 7°C / min;

[0023] The range of heating time is greater than or equal to 60s;

[0024] When the oxygen is stopped from being introduced into the diffusion device and the temperature of the silicon wafer is continued to be raised:

[0025] The range of heating rate is 7℃ / min-20℃ / min;

[0026] When the temperature rises to 850°C, the heating time is less than or equal to 480s;

[0027] When the silicon wafer is pushed forward at a constant temperature, the duration of the push forward at a constant temperature is greater than or equal to 120 seconds.

[0028] Optionally, when the silicon wafer is heated again, the heating rate is in the range of 5°C / min-8°C / min, and when the temperature is raised to 870°C, the heating time is in the range of less than or equal to 180s;

[0029] When the silicon wafer is subjected to constant temperature advancement again, the duration of the constant temperature advancement is greater than or equal to 300 seconds.

[0030] Optionally, when the silicon wafer after the phosphorus deposition process is pushed in, the pressure ranges from 90 mBar to 100 mBar.

[0031] In a second aspect, the present application provides a shingled solar cell, wherein a PN junction of the shingled solar cell is manufactured using any of the above-mentioned diffusion methods for shingled solar cells.

[0032] In the diffusion method and shingled solar cell of the embodiment of the present application, since different times of advancement treatment are performed on silicon wafers with different resistivities, thereby performing selective diffusion, the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers can be specifically improved, thereby improving the photoelectric conversion efficiency of the shingled solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic flow chart of a diffusion method for a shingled solar cell according to an embodiment of the present application;

[0034] Figure 2 is a schematic flow chart of a diffusion method for a shingled solar cell according to another embodiment of the present application;

[0035] Figure 3 It is a schematic flow chart of a diffusion method for a shingled solar cell according to another embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0037] In the related art, the resistivity range of silicon wafers used in shingled solar cells is too wide, resulting in insufficient PN junction depth and breakdown voltage of cells made from some silicon wafers. The diffusion method and shingled solar cell provided in the present application perform different times of advancement treatment on silicon wafers with different resistivities, which can specifically improve the PN junction depth and breakdown voltage of shingled solar cells made of silicon wafers.

[0038] Embodiment 1

[0039] The diffusion method of the shingled solar cell of the embodiment of the present application performs a first preset number of push-in treatments on the silicon wafer after phosphorus deposition treatment when the resistivity of the silicon wafer is greater than or equal to a preset resistivity threshold; and performs a second preset number of push-in treatments on the silicon wafer after phosphorus deposition treatment when the resistivity of the silicon wafer is less than the preset resistivity threshold.

[0040] The diffusion method of the shingled solar cell of the embodiment of the present application performs selective diffusion by performing different times of advancement treatment on silicon wafers with different resistivities. Therefore, the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers can be specifically improved, thereby improving the photoelectric conversion efficiency of the shingled solar cell.

[0041] See also Figure 1 Before the push-in treatment, the silicon wafer can also be subjected to a pre-source constant temperature oxidation treatment and a phosphorus deposition treatment; after the push-in treatment, the silicon wafer can also be subjected to a cooling treatment, a phosphorus deposition treatment and a cooling treatment.

[0042] That is to say, the diffusion method of the shingled solar cell according to the embodiment of the present application includes:

[0043] Step S11: performing a constant temperature oxidation treatment on the silicon wafer to be diffused before source connection;

[0044] Step S12: performing phosphorus deposition treatment on the silicon wafer after the constant temperature oxidation treatment before the source is turned on;

[0045] Step S131: when the resistivity of the silicon wafer is greater than or equal to a preset resistivity threshold, performing a first preset number of push-in processes on the silicon wafer after the phosphorus deposition process;

[0046] Step S132: when the resistivity of the silicon wafer is less than a preset resistivity threshold, performing a second preset number of push-in processes on the silicon wafer after the phosphorus deposition process;

[0047] Step S14: performing a cooling process on the silicon wafer after the advancement process;

[0048] Step S15: performing phosphorus deposition treatment on the silicon wafer after the cooling treatment;

[0049] Step S16: performing a cooling process on the silicon wafer after the phosphorus deposition process.

[0050] In this way, the PN junction of the shingled solar cell is made through diffusion.

[0051] Specifically, the diffusion device may include a diffusion furnace tube. Gas required for diffusion may be introduced into the diffusion furnace tube. The pressure mentioned herein refers to the pressure inside the diffusion furnace tube. The temperature mentioned herein refers to the temperature inside the diffusion furnace tube.

[0052] Optionally, in step S11, the flow rate of nitrogen is greater than or equal to 1000 sccm, the flow rate of oxygen is greater than or equal to 1300 sccm, the pressure is 85 mBar-95 mBar, the temperature is 760°C-770°C, and the duration is greater than or equal to 6 min.

[0053] Specifically, the flow rate of nitrogen is, for example, 1000sccm, 1100sccm, 1500sccm, 2000sccm, 3000sccm, 3500sccm. Specifically, the flow rate of oxygen is, for example, 1300sccm, 1400sccm, 1500sccm, 2000sccm, 2500sccm, 3200sccm. Specifically, the pressure is, for example, 85mBar, 86mBar, 87mBar, 88mBar, 89mBar, 90mBar, 91mBar, 92mBar, 93mBar, 94mBar, 95mBar. Preferably, the pressure is 90mBar. Specifically, the temperature is, for example, 760°C, 761°C, 762°C, 763°C, 764°C, 765°C, 766°C, 767°C, 768°C, 769°C, 770°C. Further, the temperature is, for example, 766°C, 767°C, 768°C, 769°C, 770°C. Preferably, the temperature is 768°C. Specifically, the duration is, for example, 6 min, 7 min, 10 min, 15 min, 20 min, 25 min, 30 min. Please note that constant temperature may refer to the temperature fluctuating constantly within the aforementioned range, or may refer to the temperature being a fixed value within the aforementioned range.

[0054] In this way, when the silicon wafer is subjected to constant temperature oxidation treatment before source opening, the flow rate, pressure, temperature and duration of nitrogen and oxygen are in an appropriate range, so that the effect of the constant temperature oxidation treatment before source opening is better, the square resistance can be improved, and thus the uniformity of diffusion can be improved.

[0055] Optionally, in step S12, the silicon wafer after the constant temperature oxidation treatment before the source is turned on may be subjected to two phosphorus deposition treatments. In other words, step S12 includes: performing a first phosphorus deposition treatment on the silicon wafer after the constant temperature oxidation treatment before the source is turned on; and performing a second phosphorus deposition treatment on the silicon wafer after the first phosphorus deposition treatment. In this way, phosphorus deposition is enhanced by two phosphorus deposition treatments.

[0056] Specifically, the diffusion source is a phosphorus source. The phosphorus source includes a liquid source of phosphorus oxychloride POCl3. It can be understood that a small amount of nitrogen is used as a protective gas to blow phosphorus oxychloride POCl3 into the diffusion equipment so that phosphorus oxychloride POCl3 is evenly distributed in the diffusion equipment. Oxygen O2 is used to react with phosphorus oxychloride POCl3 to generate phosphorus pentoxide P2O5. Phosphorus pentoxide P2O5, as an impurity source, reacts with silicon to generate silicon dioxide SIO2 and phosphorus P. In this way, phosphorus can be deposited on a silicon wafer.

[0057] Specifically, in the step of performing the first phosphorus deposition treatment on the silicon wafer after the constant temperature oxidation treatment before the source is turned on, the temperature range is 760℃-770℃, the pressure range is 85mBar-95mBar, the flow rate of small nitrogen is greater than or equal to 1200sccm, the flow rate of nitrogen is greater than or equal to 1800sccm, the flow rate of oxygen is greater than or equal to 1000sccm, and the time range is greater than or equal to 300s.

[0058] Please note that small nitrogen refers to diffused nitrogen, that is, a small amount of nitrogen is used to carry the phosphorus source into the diffusion equipment.

[0059] Further, the temperature is, for example, 760°C, 761°C, 762°C, 763°C, 764°C, 765°C, 766°C, 767°C, 768°C, 769°C, 770°C. Further, the temperature is, for example, 766°C, 767°C, 768°C, 769°C, 770°C. Preferably, the temperature is 768°C. Further, the pressure is, for example, 85mBar, 86mBar, 87mBar, 88mBar, 89mBar, 90mBar, 91mBar, 92mBar, 93mBar, 94mBar, 95mBar. Preferably, the pressure is 90mBar. Further, the flow rate of small nitrogen is, for example, 1200sccm, 1300sccm, 1400sccm, 1500sccm, 2000sccm, 2500sccm, 3200sccm. Further, the flow rate of nitrogen is, for example, 1800sccm, 1900sccm, 2000sccm, 2500sccm, 2800sccm, 3000sccm, 3200sccm. Further, the flow rate of oxygen is, for example, 1000sccm, 1100sccm, 1300sccm, 1500sccm, 2000sccm, 2500sccm, 3200sccm. Further, the duration is, for example, 300s, 310s, 350s, 400s, 500s, 650s, 700s.

[0060] In this way, when the silicon wafer is subjected to the first phosphorus deposition treatment, the gas flow rate, pressure, temperature and duration are within the appropriate range, providing a suitable environment and raw materials for the chemical reaction of the phosphorus source, and improving the efficiency and effect of the deposition. Moreover, the flow rate of the small nitrogen is within the aforementioned range, which can smoothly bring the phosphorus source into the diffusion device and make the phosphorus source evenly distributed in the diffusion device, so as to be evenly deposited on the silicon wafer.

[0061] Specifically, in the step of performing a second phosphorus deposition treatment on the silicon wafer after the first phosphorus deposition treatment, the temperature range is 770°C-780°C, the pressure range is 85mBar-95mBar, the flow rate of small nitrogen is greater than or equal to 1200sccm, the flow rate of nitrogen is greater than or equal to 1800sccm, the flow rate of oxygen is greater than or equal to 1000sccm, and the time range is greater than or equal to 300s.

[0062] Further, the temperature is, for example, 770°C, 771°C, 772°C, 773°C, 774°C, 775°C, 776°C, 777°C, 778°C, 779°C, 780°C. Further, the temperature is, for example, 776°C, 777°C, 778°C, 779°C, 780°C. Preferably, the temperature is 778°C. Further, the pressure is, for example, 85mBar, 86mBar, 87mBar, 88mBar, 89mBar, 90mBar, 91mBar, 92mBar, 93mBar, 94mBar, 95mBar. Preferably, the pressure is 90mBar. Further, the flow rate of small nitrogen is, for example, 1200sccm, 1300sccm, 1400sccm, 1500sccm, 2000sccm, 2500sccm, 3200sccm. Further, the flow rate of nitrogen is, for example, 1800sccm, 1900sccm, 2000sccm, 2500sccm, 2800sccm, 3000sccm, 3200sccm. Further, the flow rate of oxygen is, for example, 1000sccm, 1100sccm, 1300sccm, 1500sccm, 2000sccm, 2500sccm, 3200sccm. Further, the duration is, for example, 300s, 310s, 350s, 400s, 500s, 650s, 700s.

[0063] In this way, when the silicon wafer is subjected to the second phosphorus deposition treatment, the gas flow rate, pressure, temperature and duration are within the appropriate range, providing a suitable environment and raw materials for the chemical reaction of the phosphorus source, and improving the efficiency and effect of the deposition. Moreover, the flow rate of the small nitrogen is within the aforementioned range, which can smoothly bring the phosphorus source into the diffusion device and make the phosphorus source evenly distributed in the diffusion device, so as to be evenly deposited on the silicon wafer.

[0064] Optionally, in step S14, the cooling rate is less than or equal to 5°C / min, the nitrogen flow rate is greater than or equal to 3600sccm, the pressure range is 90-100mbar, the cooling time range is greater than or equal to 30min, and the temperature range is greater than or equal to 790°C.

[0065] Specifically, the cooling rate is, for example, 5°C / min, 4.8°C / min, 4°C / min, 3.8°C / min, 2.5°C / min, and 1°C / min. Specifically, the nitrogen flow rate is, for example, 3600sccm, 3700sccm, 4000sccm, 4200sccm, 4500sccm, and 5000sccm. Specifically, the pressure is, for example, 90mbar, 91mbar, 92mbar, 93mbar, 94mbar, 95mbar, 96mbar, 97mbar, 98mbar, 99mbar, and 100mbar. Specifically, the cooling time is, for example, 30min, 31min, 35min, 37min, 40min, 45min, 50min, and 55min. Specifically, the temperature is, for example, 790°C, 792°C, 795°C, 800°C, 810°C, and 820°C.

[0066] In this way, when the silicon wafer after the advancement treatment is cooled down, the pressure, cooling rate, temperature and duration are in an appropriate range, so that the cooling treatment effect is better and the silicon wafer is prevented from being damaged by sudden temperature changes.

[0067] Optionally, in step S15, the silicon wafer after the cooling treatment may be subjected to two phosphorus deposition treatments. In other words, step S15 includes: performing a third phosphorus deposition treatment on the silicon wafer after the cooling treatment; and performing a fourth phosphorus deposition treatment on the silicon wafer after the third phosphorus deposition treatment. In this way, phosphorus deposition is enhanced by two phosphorus deposition treatments, so that the effect of phosphorus deposition is better, the phosphorus concentration in the heavily doped area can be increased, and the contact can be improved.

[0068] Specifically, in the step of performing the third phosphorus deposition treatment on the silicon wafer after the cooling treatment, the temperature range is 785°C-815°C, the pressure range is 80mBar-90mBar, the oxygen flow rate range is greater than or equal to 500sccm, the small nitrogen flow rate range is greater than or equal to 1500sccm, the large nitrogen flow rate range is greater than or equal to 750sccm, and the time range is greater than or equal to 600s.

[0069] Further, the temperature is, for example, 785°C, 786°C, 790°C, 795°C, 800°C, 808°C, 810°C, 815°C. Preferably, the temperature is 800°C. Further, the pressure is, for example, 80mBar, 81mBar, 82mBar, 83mBar, 84mBar, 85mBar, 86mBar, 87mBar, 88mBar, 89mBar, 90mBar. Preferably, the pressure is 85mBar. Further, the flow rate of oxygen is, for example, 500sccm, 510sccm, 550sccm, 600sccm, 650sccm. Further, the flow rate of nitrogen is, for example, 1500sccm, 1700sccm, 2000sccm, 2500sccm, 3200sccm. Further, the flow rate of the high nitrogen is, for example, 750 sccm, 760 sccm, 800 sccm, 820 sccm, 850 sccm. Further, the duration is, for example, 600 s, 610 s, 650 s, 700 s, 750 s, 800 s.

[0070] In this way, when the silicon wafer is subjected to the third phosphorus deposition treatment, the gas flow rate, pressure, temperature and duration are within a suitable range, so that the effect of the third phosphorus deposition treatment is better.

[0071] Specifically, in the step of performing the fourth phosphorus deposition treatment on the silicon wafer after the third phosphorus deposition treatment, the temperature range is 785°C-815°C, the pressure range is 80mBar-90mBar, the oxygen flow rate range is greater than or equal to 1500sccm, the small nitrogen flow rate range is greater than or equal to 750sccm, the large nitrogen flow rate range is greater than or equal to 750sccm, and the time range is greater than or equal to 300s.

[0072] Further, the temperature is, for example, 785°C, 786°C, 790°C, 795°C, 800°C, 808°C, 810°C, 815°C. Preferably, the temperature is 800°C. Further, the pressure is, for example, 80mBar, 81mBar, 82mBar, 83mBar, 84mBar, 85mBar, 86mBar, 87mBar, 88mBar, 89mBar, 90mBar. Preferably, the pressure is 85mBar. Further, the flow rate of oxygen is, for example, 1500sccm, 1510sccm, 1550sccm, 1600sccm, 1650sccm. Further, the flow rate of nitrogen is, for example, 750sccm, 760sccm, 800sccm, 820sccm, 850sccm. Further, the flow rate of the high nitrogen is, for example, 750 sccm, 760 sccm, 800 sccm, 820 sccm, 850 sccm. Further, the duration is, for example, 300 s, 310 s, 350 s, 400 s, 450 s, 500 s.

[0073] In this way, when the silicon wafer is subjected to the fourth phosphorus deposition treatment, the gas flow rate, pressure, temperature and duration are within a suitable range, so that the effect of the fourth phosphorus deposition treatment is better.

[0074] Optionally, in step S16, turn off the phosphorus source, stop heating, stop introducing oxygen, and introduce only protective nitrogen. After the temperature in the diffusion device drops to 770°C, introduce pure nitrogen, the flow rate of which is greater than or equal to 15000 sccm, maintain normal pressure, and the cooling time after introducing pure nitrogen is greater than or equal to 360 seconds. Please note that pure nitrogen refers to pure nitrogen.

[0075] Specifically, the flow rate of the high nitrogen is, for example, 15000 sccm, 15500 sccm, 15800 sccm, or 16000 sccm. Specifically, the duration is, for example, 360 s, 365 s, 370 s, 378 s, or 380 s.

[0076] In this way, when the silicon wafer is subjected to a cooling treatment, the gas flow rate, pressure, and duration are within an appropriate range, thereby achieving a better cooling effect and preventing the silicon wafer from being damaged by a sudden change in temperature.

[0077] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0078] Embodiment 2

[0079] In some optional embodiments, the preset resistivity threshold value ranges from 0.6Ω·cm to 0.8Ω·cm, for example, 0.6Ω·cm, 0.62Ω·cm, 0.65Ω·cm, 0.68Ω·cm, 0.7Ω·cm, 0.73Ω·cm, 0.75Ω·cm, 0.79Ω·cm, and 0.8Ω·cm.

[0080] In this way, the preset resistivity threshold is within an appropriate range, avoiding the difficulty in performing targeted advancement processing on silicon wafers with different resistivities due to the preset resistivity threshold being too low or too high, thereby avoiding poor advancement processing effect, which is beneficial to targetedly improve the PN junction depth and breakdown voltage of shingled solar cells made of silicon wafers.

[0081] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0082] Embodiment 3

[0083] In some optional embodiments, the preset resistivity threshold is 0.7 Ω·cm.

[0084] In this way, silicon wafers with a resistivity greater than or equal to 0.7Ω·cm are subjected to a first preset number of push-in treatments, and silicon wafers with a resistivity less than 0.7Ω·cm are subjected to a second preset number of push-in treatments. The classification of silicon wafers is more accurate, so that the silicon wafers can be subjected to targeted push-in treatments, resulting in better push-in treatment effects, which is beneficial to targetedly improving the PN junction depth and breakdown voltage of shingled solar cells made of silicon wafers.

[0085] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0086] Embodiment 4

[0087] In some optional embodiments, the first preset number of times is 1 time, and the second preset number of times is 2 times.

[0088] That is to say, when the resistivity of the silicon wafer is greater than or equal to the preset resistivity threshold, the silicon wafer after the phosphorus deposition treatment is subjected to one push-in treatment; when the resistivity of the silicon wafer is less than the preset resistivity threshold, the silicon wafer after the phosphorus deposition treatment is subjected to two push-in treatments.

[0089] In this way, while ensuring that the PN junction depth and breakdown voltage of the battery cell made of silicon wafers with a larger resistivity are higher, the PN junction depth and breakdown voltage of the battery cell made of silicon wafers with a smaller resistivity are increased through multiple advancements.

[0090] It is understandable that in other embodiments, the first preset number of times may also be 2 times, 3 times or other times. The second preset number of times may also be 2 times, 3 times or other times.

[0091] Embodiment 5

[0092] See also Figure 2 In some optional embodiments, the steps of performing one or the first push-in process on the silicon wafer after the phosphorus deposition process are specifically as follows:

[0093] Step S1311: turn off the phosphorus source;

[0094] Step S1312: continue to introduce oxygen and nitrogen into the diffusion device and heat up the silicon wafer;

[0095] Step S1313: stop introducing oxygen into the diffusion device, and continue to heat up the silicon wafer;

[0096] Step S1314: advancing the silicon wafer at a constant temperature.

[0097] In this way, without introducing a phosphorus source, the phosphorus deposited in the phosphorus deposition process is further diffused into the silicon wafer, which can increase the junction depth of the PN junction, thereby improving the photoelectric conversion efficiency of the solar cell.

[0098] Specifically, in step S1311, the phosphorus source refers to a diffusion source. The phosphorus source includes a liquid source of phosphorus oxychloride POCl3. In this way, phosphorus pentoxide P2O5 generated by the decomposition of POCl3 acts as an impurity source and reacts with silicon to generate silicon dioxide SIO2 and phosphorus P.

[0099] Specifically, in step S1312 and step S1313, the heating rates of the heating advancement may be the same or different, which is not limited here.

[0100] Specifically, in step S1314, constant temperature may refer to that the temperature fluctuates within a range, or may refer to that the temperature is constant at a fixed value within the range.

[0101] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0102] Embodiment 6

[0103] See also Figure 3 In some optional embodiments, the steps of performing a second push-in process on the silicon wafer based on the first push-in process are specifically as follows:

[0104] Step S1321: heating the silicon wafer again;

[0105] Step S1322: the silicon wafer is pushed forward at a constant temperature again.

[0106] In this way, the silicon wafer with a resistivity less than a preset resistivity threshold is pushed forward twice, so that the phosphorus deposited in the phosphorus deposition process step further diffuses into the silicon wafer, which can increase the junction depth of the PN junction, thereby improving the photoelectric conversion efficiency of the solar cell.

[0107] Specifically, in step S1321, the heating rates of the heating advancement may be the same or different, which is not limited here.

[0108] Specifically, in step S1322, constant temperature may refer to that the temperature fluctuates within a range, or may refer to that the temperature is constant at a fixed value within the range.

[0109] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0110] Embodiment 7

[0111] In some optional embodiments, in step S1312, the flow rate of nitrogen is in the range of greater than or equal to 1800 sccm, the flow rate of oxygen is in the range of greater than or equal to 650 sccm, the heating rate is in the range of greater than 7°C / min, and the heating time is in the range of greater than or equal to 60s.

[0112] Specifically, the flow rate of nitrogen is, for example, 1800sccm, 1850sccm, 1900sccm, 2000sccm, 2500sccm, 3000sccm. Specifically, the flow rate of oxygen is, for example, 650sccm, 660sccm, 700sccm, 750sccm, 800sccm. Specifically, the heating rate is, for example, 7°C / min, 7.2°C / min, 7.5°C / min, 7.8°C / min, 8°C / min. Specifically, the heating time is, for example, 60s, 62s, 65s, 68s, 70s, 71s, 65s, 80s.

[0113] In this way, the gas flow rate, heating rate and heating time are within a suitable range, so that the heating effect is better, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cells made of silicon wafers.

[0114] In some optional embodiments, in step S1313, the heating rate ranges from 7°C / min to 20°C / min, and when the temperature is raised to 850°C, the heating time ranges from less than or equal to 480s.

[0115] Specifically, the heating rate is, for example, 7°C / min, 8°C / min, 10°C / min, 13°C / min, 15°C / min, 18°C / min, 20°C / min. Specifically, when the temperature is raised to 850°C, the heating time is, for example, 480s, 478s, 475s, 470s, 466s, 465s, 460s.

[0116] In this way, the heating rate and heating time are within a suitable range, so that the heating effect is better, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cells made of silicon wafers.

[0117] In some optional embodiments, in step S1314, the duration of the constant temperature advancement is greater than or equal to 120 seconds, such as 120 seconds, 122 seconds, 125 seconds, 128 seconds, 130 seconds, 131 seconds, 135 seconds, and 140 seconds. In this way, the duration of the constant temperature advancement is within a suitable range, so that the effect of the constant temperature advancement is better, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers.

[0118] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0119] Embodiment 8

[0120] In some optional embodiments, in step S1321, the heating rate ranges from 5°C / min to 8°C / min, and when the temperature rises to 870°C, the heating time is less than or equal to 180s.

[0121] Specifically, the heating rate is, for example, 5°C / min, 6°C / min, 7°C / min, 8°C / min. Preferably, the heating rate is 7°C / min. Specifically, when the temperature is raised to 870°C, the heating time is, for example, 180s, 175s, 173s, 170s, 166s, 165s, 160s.

[0122] In this way, the heating rate and heating time are within a suitable range, so that the heating effect is better, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cells made of silicon wafers.

[0123] In some optional embodiments, in step S1322, the duration of the constant temperature advancement is greater than or equal to 300 seconds, such as 300 seconds, 310 seconds, 350 seconds, 400 seconds, 460 seconds, and 500 seconds. In this way, the duration of the constant temperature advancement is within a suitable range, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers.

[0124] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0125] Embodiment 9

[0126] In some optional embodiments, when the silicon wafer after phosphorus deposition is subjected to a push-in process, the pressure ranges from 90mBar to 100mBar. For example, 90mBar, 91mBar, 92mBar, 93mBar, 94mBar, 95mBar, 96mBar, 97mBar, 98mBar, 99mBar, 100mBar. Preferably, the pressure is 95mBar. In this way, the pressure is within a suitable range, providing a suitable environment for the push-in process, which is beneficial to improving the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers.

[0127] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0128] Embodiment 10

[0129] This embodiment provides a shingled solar cell. The PN junction of the shingled solar cell is manufactured by the diffusion method of the shingled solar cell of any of the above embodiments.

[0130] The shingled solar cell of the embodiment of the present application performs selective diffusion by performing different times of push-in treatment on silicon wafers with different resistivities. Therefore, the PN junction depth and breakdown voltage of the shingled solar cell made of silicon wafers can be specifically improved, thereby improving the photoelectric conversion efficiency of the shingled solar cell.

[0131] For other explanations and descriptions about this embodiment, please refer to other parts of this document. To avoid redundancy, they will not be repeated here.

[0132] In summary, for silicon wafers with a resistivity of less than 0.7Ω·cm, the shingled solar cell made by the diffusion method of the related art has a junction depth of 0.27μm and a reverse breakdown voltage of 17.4V. The shingled solar cell made by the diffusion method of the present application has a junction depth of 0.32μm, which is 0.05μm higher than that of the related art, and a reverse breakdown voltage of 21.2V, which is 3.8V higher than that of the related art.

[0133] For silicon wafers with a resistivity greater than or equal to 0.7Ω·cm, the junction depth of the shingled solar cell made by the diffusion method of the related art is 0.21μm. The junction depth of the shingled solar cell made by the diffusion method of the present application is 0.28μm, which is 0.07μm higher than that of the related art.

[0134] For silicon wafers with a resistivity less than 0.7Ω·cm, the breakdown voltage of the shingled solar cell made by the diffusion method of the related art is 17.4V. The breakdown voltage of the shingled solar cell made by the diffusion method of the present application is 21.2V, which is 3.8V higher than that of the related art.

[0135] For silicon wafers with a resistivity greater than or equal to 0.7Ω·cm, the breakdown voltage of the shingled solar cell made by the diffusion method of the related art is 20.7V. The breakdown voltage of the shingled solar cell made by the diffusion method of the present application is 23.9V, which is 3.2V higher than that of the related art.

[0136] For silicon wafers with a resistivity of less than 0.7Ω·cm, the conversion efficiency of the shingled solar cell made by the diffusion method of the related art is 22.50%. The conversion efficiency of the shingled solar cell made by the diffusion method of the present application is 22.52%, which is 0.02% higher than that of the related art.

[0137] For silicon wafers with a resistivity greater than or equal to 0.7Ω·cm, the conversion efficiency of the shingled solar cell made by the diffusion method of the related art is 22.60%. The conversion efficiency of the shingled solar cell made by the diffusion method of the present application is 22.68%, which is 0.08% higher than that of the related art.

[0138] The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A diffusion method for a shingled solar cell, characterized in that: include: The silicon wafer to be diffused is subjected to constant temperature oxidation treatment before being passed through the source; Phosphorus deposition treatment is performed on silicon wafers that have been subjected to constant temperature oxidation treatment before the source is turned on; When the resistivity of the silicon wafer is greater than or equal to a preset resistivity threshold, performing a first preset number of push-in treatments on the silicon wafer after the phosphorus deposition treatment; When the resistivity of the silicon wafer is less than the preset resistivity threshold, performing a second preset number of push-in treatments on the silicon wafer after the phosphorus deposition treatment; Performing cooling treatment on the silicon wafer after the advancement treatment; Performing phosphorus deposition treatment on the silicon wafer after the cooling treatment; Performing a cooling process on the silicon wafer after the phosphorus deposition process; The preset resistivity threshold value ranges from 0.6Ω·cm to 0.8Ω·cm; The first preset number of times is 1, and the second preset number of times is 2; The steps of performing a first push-in treatment on the silicon wafer after phosphorus deposition treatment are specifically as follows: Turn off the phosphorus source; Continue to introduce oxygen and nitrogen into the diffusion device and heat the silicon wafer; Stopping the introduction of oxygen into the diffusion device and continuing to heat up the silicon wafer; The silicon wafer is pushed forward at a constant temperature.

2. The diffusion method of shingled solar cells according to claim 1, characterized in that: The preset resistivity threshold is 0.7Ω·cm.

3. The diffusion method of shingled solar cells according to claim 1, characterized in that: The specific steps of performing a second push-in process on the silicon wafer based on the first push-in process are: The silicon wafer is heated up again; The silicon wafer is again pushed forward at a constant temperature.

4. The diffusion method of shingled solar cells according to claim 1 or 3, characterized in that: When oxygen and nitrogen continue to be introduced into the diffusion equipment and the temperature of the silicon wafer is increased: The flow rate of nitrogen is in the range of greater than or equal to 1800 sccm; The flow rate of oxygen is in the range of greater than or equal to 650 sccm; The range of heating rate is greater than 7°C / min; The range of heating time is greater than or equal to 60s; When the oxygen is stopped from being introduced into the diffusion device and the temperature of the silicon wafer is continued to be raised: The range of heating rate is 7℃ / min-20℃ / min; When the temperature rises to 850°C, the heating time is less than or equal to 480s; When the silicon wafer is pushed forward at a constant temperature, the duration of the push forward at a constant temperature is greater than or equal to 120 seconds.

5. The diffusion method of shingled solar cells according to claim 3, characterized in that: When the silicon wafer is heated again, the heating rate is in the range of 5°C / min-8°C / min, and when the temperature is raised to 870°C, the heating time is in the range of less than or equal to 180s; When the silicon wafer is subjected to constant temperature advancement again, the duration of the constant temperature advancement is greater than or equal to 300 seconds.

6. The diffusion method of shingled solar cells according to claim 1, characterized in that: When the silicon wafer after the phosphorus deposition process is pushed in, the pressure ranges from 90 mBar to 100 mBar.

7. A shingled solar cell, characterized in that: The PN junction of the shingled solar cell is manufactured by the diffusion method of the shingled solar cell according to any one of claims 1 to 6.

Images