Method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter and its use

Abstract

The present application provides a method for manufacturing a shallow junction diffused emitter crystalline silicon solar cell and its use. The manufacturing method includes a diffusion process and a chain oxidation process, the diffusion process includes low temperature diffusion and high temperature drive-in, and the chain oxidation process includes high temperature chain oxidation. The present application first optimizes the diffusion process to manufacture a low doped diffused shallow junction with a depth of 0.15um, and then utilizes the photon thermal activation radiation energy of the high temperature chain oxidation to form a constant dose concentration of doping on the surface of the diffusion layer, thereby solving the mismatch problem of forming alloy ohmic contact with the silver paste, and finally achieving a high photoelectric conversion efficiency improvement.

Description

Technical Field

[0001] The present application relates to the technical field of photovoltaic power generation, relates to the manufacturing field of crystalline silicon solar cells, and particularly relates to a manufacturing method of a crystalline silicon solar cell with a shallow junction diffusion emitter and its use.

Background Art

[0002] As non-renewable energy is gradually depleted and global warming is becoming increasingly serious, establishing an energy system mainly based on renewable energy and realizing sustainable development friendly to the environment has become a common global understanding. Currently, in the world, more than 130 countries and regions have successively announced their goals towards "carbon neutrality". Furthermore, in some countries, in order to effectively respond to the crises and challenges caused by climate change, the responsibility of "carbon neutrality" has been clarified in the form of legislation. Currently, the penetration rate of renewable energy in the world is still at a low level and has a broad development space. Among them, the economic superiority of photovoltaic power generation is obvious, the power generation cost is lower than that of coal power generation, and it will continue to decline in the future, and its development potential is inestimable.

[0003] Moreover, it is particularly important to improve the photoelectric conversion efficiency of solar cells. Currently, for conventional high-efficiency cells, the junction depth of the diffusion emitter is basically about 0.2 um to 0.3 um, and the absorption loss for short waves is obvious. When trying to fabricate a diffusion shallow junction of 0.1 um to 0.2 um by the conventional diffusion process method, the diffusion sheet resistance is very high and the surface concentration is low. In this case, problems occur in the alloy ohmic contact in the screen process, and it is very easy to render the photoelectric conversion efficiency of the solar cell ineffective. Therefore, currently, it is very difficult to obtain a diffusion shallow junction by the conventional solar energy manufacturing process.

[0004] CN103943719A discloses a method for controlling phosphorus doping concentration using a method that combines pre-oxidation with low-temperature-high-temperature variable-temperature diffusion. This method includes pre-oxidation and a three-step low-temperature-high-temperature variable-temperature diffusion process. By optimizing the temperature gradient, this process can precisely control the phosphorus doping concentration gradient, achieve good PN junction and sheet resistance uniformity, and improve the conversion efficiency of solar cells. This invention mainly describes adjustments made by optimizing the diffusion process, and focuses on a method for controlling phosphorus doping concentration using a variable-temperature diffusion method. However, it is limited to the optimization of a single diffusion step and only achieves optimization of the diffusion distribution of the ECV curve.

[0005] CN105280484A discloses a diffusion process for high-efficiency, high-sheet-resistance battery sheets of crystalline silicon, mainly comprising the steps of (1) entering the furnace, (2) low-temperature oxidation, (3) low-temperature gas reaction deposition, (4) high-temperature impurity redistribution, (5) high-temperature gas reaction deposition, (6) low-temperature impurity redistribution, (7) low-temperature gas reaction deposition, (8) low-temperature impurity redistribution, and (9) removal from the furnace. Similar to CN103943719A, it is limited to the optimization of a single diffusion process, and there is a need to further improve and break through the photoelectric conversion efficiency of solar energy.

[0006] CN204905275U discloses an apparatus for improving the PID resistance of solar cells based on chain oxidation. This apparatus mainly includes an ozone generator, a compressed air transport line, and a mixer. The ozone outlet of the ozone generator is connected to the mixer by the ozone transport line, compressed air is connected to the mixer by the compressed air transport line, the mixer is connected to the mixed gas output terminal by the mixed gas transport line, and the mixed gas output terminal is connected to the intake of a gas uniform distribution plate. The gas uniform distribution plate is hollow inside, with an intake opening at one end and multiple exhaust holes uniformly arranged on the lower end wall. The gas uniform distribution plate is mounted above the silicon wafer transport rail between the etching apparatus and the PECVD apparatus of a battery sheet manufacturing device, and the exhaust holes face the silicon wafer transport rail. A device for controlling the amount of ozone generated is attached to the ozone generator. This utility model can rapidly grow a silicon oxide film on the silicon wafer surface before depositing a silicon nitride film, thereby improving the PID resistance of solar cells and extending their service life. However, the concept behind this patent only considers the reliability of solar cells and does not improve or enhance the photoelectric conversion efficiency of solar cells using a high-temperature method.

[0007] Currently, the photoelectric conversion efficiency of conventional solar cells is approaching a bottleneck, and further optimization of process details to achieve improvements and breakthroughs is a challenge that engineers grapple with daily, necessitating the search for new breakthrough points. [Overview of the project]

[0008] The following is a summary of the matters described in detail in this invention. This summary is not intended to limit the scope of the claims.

[0009] The present invention aims to provide a method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter and a method for using the same.

[0010] To achieve the objective of this application, the following technical measures were taken.

[0011] The first objective of this application is to provide a method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter, including a diffusion process and a chain oxidation process.

[0012] The diffusion process includes low-temperature diffusion and high-temperature drive-in, and the chain oxidation process includes high-temperature chain oxidation.

[0013] This application analyzes influencing factors such as temperature, time, flow rate, and composition through DOE experiments of the diffusion process, revealing that important factors that alter the ECV curve of the diffusion process include surface concentration, emitter junction depth, complementary error distribution, and Gaussian doping profile curves. Next, the principle of high-temperature chain oxidation was understood, and its influence on surface doping during experiments was explored. Finally, by linking it to the principle of photovoltaic power generation in crystalline silicon solar cells, the diffusion process and chain oxidation process were combined to produce a diffusion emitter junction of approximately 0.15 μm, achieve good ohmic alloy contact with a high surface doping concentration, improve short-wave spectral absorption, and enhance the photoelectric conversion efficiency of the solar cell. This application demonstrates a significant inventive step.

[0014] This invention first optimizes the diffusion process to produce a shallow, low-doping diffusion bond with a depth of 0.15 μm, and then uses the photon thermal activation radiant energy of high-temperature chain oxidation to form a doping layer with a constant dose concentration on the surface of the diffusion layer, thereby solving the mismatch problem that would otherwise occur when forming ohmic contact between the silver paste and the alloy. Ultimately, a significant improvement in photoelectric conversion efficiency is achieved.

[0015] A preferred technical solution of the present invention includes, in order, entering a boat, first heating, first constant temperature, vacuum stabilization, vacuum leak detection, oxidation, introduction of a first low-temperature diffusion source, introduction of a second low-temperature diffusion source, second heating, second constant temperature, high-temperature drive-in, first cooling, supplemental diffusion, purging, PSG deposition reaction, oxidation reaction, second cooling, nitrogen gas filling, and discharge from the boat.

[0016] Preferably, the low-temperature diffusion includes diffusing a stationary source at a constant temperature.

[0017] Preferably, the fixative source is phosphorus oxychloride.

[0018] Preferably, the low-temperature diffusion includes the introduction of a first low-temperature diffusion source and the introduction of a second low-temperature diffusion source.

[0019] Preferably, the temperature at which the first low-temperature diffusion source is introduced is 770 to 790°C, where the temperature may be 770°C, 772°C, 774°C, 776°C, 778°C, 780°C, 782°C, 784°C, 786°C, 788°C, or 790°C, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0020] Preferably, the time for introducing the first low-temperature diffusion source is 220 to 260 s, where this time may be 220 s, 225 s, 230 s, 235 s, 240 s, 245 s, 250 s, 255 s, or 260 s, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0021] Preferably, the introduction of the first low-temperature diffusion source The first nitrogen The flow rate is 1000-1100 sccm, where, The first nitrogen The flow rate may be 1000 sccm, 1020 sccm, 1040 sccm, 1060 sccm, 1080 sccm, or 1100 sccm, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0022] Preferably, the oxygen flow rate of the first low-temperature diffusion source introduction is 450 to 550 sccm, where the oxygen flow rate may be 450 sccm, 460 sccm, 470 sccm, 480 sccm, 490 sccm, 500 sccm, 510 sccm, 520 sccm, 530 sccm, 540 sccm, or 550 sccm, and is not limited to the values ​​listed, and other values ​​within that range that are not listed may also be used.

[0023] Preferably, the flow rate of the introduction of the first low-temperature diffusion source The second nitrogen is 0 sccm.

[0024] Preferably, the furnace tube pressure of the introduction of the first low-temperature diffusion source is 50 to 60 mbar, where the furnace tube pressure may be 50 mbar, 51 mbar, 52 mbar, 53 mbar, 54 mbar, 55 mbar, 56 mbar, 57 mbar, 58 mbar, 59 mbar or 60 mbar, etc., and is not limited to the recited values, and other unrecited values within the numerical range may be used similarly.

[0025] Preferably, the temperature of the introduction of the second low-temperature diffusion source is 790 to 810 °C, where the temperature may be 790 °C, 792 °C, 794 °C, 796 °C, 798 °C, 800 °C, 802 °C, 804 °C, 806 °C, 808 °C or 810 °C, etc., and is not limited to the recited values, and other unrecited values within the numerical range may be used similarly.

[0026] Preferably, the time of the introduction of the second low-temperature diffusion source is 190 to 230 s, where the time may be 190 s, 195 s, 200 s, 205 s, 210 s, 215 s, 220 s, 225 s or 230 s, etc., and is not limited to the recited values, and other unrecited values within the numerical range may be used similarly.

[0027] Preferably, the The first nitrogen flow rate of the introduction of the second low-temperature diffusion source is 1100 to 1200 sccm, where the The first nitrogen flow rate may be 1100 sccm, 1120 sccm, 1140 sccm, 1160 sccm, 1180 sccm or 1200 sccm, etc., and is not limited to the recited values, and other unrecited values within the numerical range may be used similarly.

[0028] Preferably, the oxygen flow rate for the introduction of the second low-temperature diffusion source is 550 to 650 sccm. Here, the oxygen flow rate may be, for example, 550 sccm, 560 sccm, 570 sccm, 580 sccm, 590 sccm, 600 sccm, 610 sccm, 620 sccm, 630 sccm, 640 sccm, or 650 sccm, etc., and is not limited to the recited values. Other unrecited values within this numerical range may be used as well.

[0029] Preferably, for the introduction of the second low-temperature diffusion source The second nitrogen the flow rate is 0 sccm.

[0030] Preferably, the furnace tube pressure for the introduction of the second low-temperature diffusion source is 50 to 60 mbar. Here, the furnace tube pressure may be, for example, 50 mbar, 52 mbar, 54 mbar, 56 mbar, 58 mbar, or 60 mbar, etc., and is not limited to the recited values. Other unrecited values within this numerical range may be used as well.

[0031] In the present application, during low-temperature diffusion, a fixed source amount (phosphorus oxychloride) is introduced at about 800 °C, that is, diffusion of the fixed source is performed, and the diffusion distribution curve at this time satisfies the complementary error distribution.

[0032] As a preferred technical solution of the present application, the high-temperature drive-in includes driving a phosphorus source on the surface of crystalline silicon into the silicon substrate at a high temperature.

[0033] Preferably, the time of the high-temperature drive-in is 350 to 370 s. Here, the time may be, for example, 350 s, 352 s, 354 s, 356 s, 358 s, 360 s, 362 s, 364 s, 366 s, 368 s, or 370 s, etc., and is not limited to the recited values. Other unrecited values within this numerical range may be used as well.

[0034] Preferably, the temperature of the high-temperature drive-in is 800 to 900°C, where the temperature may be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, 890°C, or 900°C, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0035] Preferably, the high-temperature drive-in The first nitrogen The flow rate is 750-850 sccm, where, The first nitrogen The flow rate may be 750 sccm, 760 sccm, 770 sccm, 780 sccm, 790 sccm, 800 sccm, 810 sccm, 820 sccm, 830 sccm, 840 sccm, or 850 sccm, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0036] Preferably, the oxygen flow rate of the high-temperature drive-in is 0 sccm.

[0037] Preferably, the high-temperature drive-in The second nitrogen The flow rate is 950-1050 sccm, where, The second nitrogen The flow rate may be 950 sccm, 960 sccm, 970 sccm, 980 sccm, 990 sccm, 1000 sccm, 1010 sccm, 1020 sccm, 1030 sccm, 1040 sccm, or 1050 sccm, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0038] Preferably, the furnace tube pressure of the high-temperature drive-in is 50 to 60 mbar, where the furnace tube pressure may be 50 mbar, 51 mbar, 52 mbar, 53 mbar, 54 mbar, 55 mbar, 56 mbar, 57 mbar, 58 mbar, 59 mbar, or 60 mbar, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0039] In this invention, after stopping the introduction of the source amount, the temperature is raised to approximately 850°C, and a high-temperature drive-in is performed to fix the doping source amount under certain conditions, i.e., diffusion of a constant-weight source is performed, and the diffusion distribution curve at this time satisfies a Gaussian distribution.

[0040] In the present invention, a preferred technical method is to use a temperature of 700 to 800°C for the PSG deposition reaction, where the temperature may be 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, or 800°C, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0041] Preferably, the time for the PSG deposition reaction is 700 to 800 s, where the time may be 700 s, 710 s, 720 s, 730 s, 740 s, 750 s, 760 s, 770 s, 780 s, 790 s, or 800 s, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0042] Preferably, phosphorus oxychloride is introduced during the PSG deposition reaction.

[0043] Preferably, the PSG deposition reaction The first nitrogen The flow rate is 1250-1350 sccm, where, The first nitrogen The flow rate may be 1250 sccm, 1260 sccm, 1270 sccm, 1280 sccm, 1290 sccm, 1300 sccm, 1310 sccm, 1320 sccm, 1330 sccm, 1340 sccm, or 1350 sccm, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0044] Preferably, the oxygen flow rate for the PSG deposition reaction is 550 to 650 sccm, where the oxygen flow rate may be 550 sccm, 560 sccm, 570 sccm, 580 sccm, 590 sccm, 600 sccm, 610 sccm, 620 sccm, 630 sccm, 640 sccm, or 650 sccm, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0045] Preferably, the PSG deposition reaction The second nitrogen The flow rate is 0 sccm.

[0046] Preferably, the furnace tube pressure for the PSG deposition reaction is 55 to 65 mbar, where the furnace tube pressure may be 55 mbar, 56 mbar, 57 mbar, 58 mbar, 59 mbar, 60 mbar, 61 mbar, 62 mbar, 63 mbar, 64 mbar, or 65 mbar, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0047] A preferred technical method of this invention involves performing a vacuum treatment on the furnace tube during the first heating and first constant temperature stages.

[0048] Preferably, at the first constant temperature, First Nitrogen The pipeline is purged by introducing a purging device, the flow rate of which is 450 to 550 sccm, where the flow rate may be 450 sccm, 460 sccm, 470 sccm, 480 sccm, 490 sccm, 500 sccm, 510 sccm, 520 sccm, 530 sccm, 540 sccm, or 550 sccm, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0049] Preferably, after the pressure stabilizes during the vacuum stabilization, all gas introductions are closed and the pressure in the furnace tube is maintained at 50-60 mbar, where the pressure may be 50 mbar, 51 mbar, 52 mbar, 53 mbar, 54 mbar, 55 mbar, 56 mbar, 57 mbar, 58 mbar, 59 mbar, or 60 mbar, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0050] Preferably, the oxidation includes providing protection for the growth of a single silicon oxide layer on the surface of the crystalline silicon wafer.

[0051] In a preferred technical application of the present invention, the temperature reached by the second heating is 830 to 870°C, where the temperature reached may be 830°C, 835°C, 840°C, 845°C, 850°C, 855°C, 860°C, 865°C, or 870°C, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0052] Preferably, during the second heating, nitrogen gas is introduced to remove any remaining phosphorus oxychloride.

[0053] Preferably, in the second heating, The second nitrogen The flow rate is 950-1050 sccm, where, The second nitrogen The flow rate may be 950 sccm, 960 sccm, 970 sccm, 980 sccm, 990 sccm, 1000 sccm, 1010 sccm, 1020 sccm, 1030 sccm, 1040 sccm, or 1050 sccm, and is not limited to the values ​​listed above. Other values ​​within that range that are not listed may also be used.

[0054] Preferably, at the second constant temperature, oxygen is introduced to allow the remaining phosphorus oxychloride to react further.

[0055] Preferably, at the second constant temperature, the oxygen flow rate is 550 to 650 sccm, where the oxygen flow rate may be 550 sccm, 560 sccm, 570 sccm, 580 sccm, 590 sccm, 600 sccm, 610 sccm, 620 sccm, 630 sccm, 640 sccm, or 650 sccm, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0056] In a preferred technical arrangement of the present invention, the temperature of the first cooling is 750 to 810°C, where the temperature may be 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, or 810°C, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0057] In this application, the first temperature reduction is set to the supplemental diffusion setting temperature.

[0058] Preferably, the supplementation diffusion is used to correct a defect in which localized doping of the crystalline silicon wafer is too low due to high-temperature drive-in.

[0059] Preferably, the purging removes any phosphorus oxychloride remaining in the furnace tubes.

[0060] Preferably, the oxidation reaction removes the phosphorus oxychloride introduced into the PSG deposition reaction.

[0061] Preferably, the second cooling is used to repair lattice dislocations in the crystalline silicon wafer.

[0062] Preferably, the nitrogen gas filling is used to restore the furnace tube to an atmospheric pressure state.

[0063] A preferred technical example of the present invention is the chain oxidation process, which includes high-temperature chain oxidation.

[0064] Preferably, the temperature of the high-temperature chain oxidation is 660 to 670°C, where the temperature may be 660°C, 662°C, 664°C, 666°C, 668°C, or 670°C, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0065] Preferably, the time for the high-temperature chain oxidation is 1 to 5 minutes, where the time may be 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0066] Preferably, the oxygen flow rate for the high-temperature chain oxidation is 95 to 105 slm, where the oxygen flow rate may be 95 slm, 96 slm, 97 slm, 98 slm, 99 slm, 100 slm, 101 slm, 102 slm, 103 slm, 104 slm, or 105 slm, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0067] Preferably, the nitrogen gas flow rate for the high-temperature chain oxidation is 5 to 15 slm, where the nitrogen gas flow rate may be 5 slm, 6 slm, 7 slm, 8 slm, 9 slm, 10 slm, 11 slm, 12 slm, 13 slm, 14 slm, or 15 slm, and is not limited to the values ​​listed above; other values ​​within that range that are not listed may also be used.

[0068] This invention creates a diffusion curve doping profile by controlling the amount of low-temperature diffusion source and the high-temperature drive-in time. If the surface doping concentration of the diffusion curve is low, it will cause subsequent failure of alloy ohmic contacts, so it is necessary to activate surface doping by introducing high-temperature chain oxidation.

[0069] High-temperature chain oxidation furnaces are a heat treatment method with a very fast heating rate and a very short holding time. The heating rate can reach 10-100°C / s. Generally, infrared halogen lamps are used for heating, and the current and power are large during heating. During the heating process of the halogen lamp, a large amount of high-energy electrons are emitted. When these high-energy electrons collide with the silicon wafer, the irradiated electrons interact with the lattice, disrupting the position of atoms within the lattice, causing a displacement effect on the atoms, and simultaneously forming hole-interstitial atom pairs. At the same time, there are two types of phosphorus diffusion: interstitial diffusion and substitutional diffusion, and collisions of high-energy electrons reduce the difficulty of phosphorus diffusion. Chain oxidation devices, when heated using infrared halogen lamps and when a stationary source is present on the surface of the silicon wafer, trigger a diffusion enhancement mechanism, resulting in the redistribution of the phosphorus source.

[0070] According to the above principle, when different temperature conditions for high-temperature chain oxidation were tested, it was discovered that the higher the temperature, the stronger the photon thermal activation radiation capability, the higher the effective diffusion activation doping capability, and the greater the change in thin-layer sheet resistance. Furthermore, it was found that the greater the difference in sheet resistance corresponding to different chain oxidation temperatures, the stronger the activation doping capability. Therefore, this invention uses high-temperature photon thermal activation radiation to activate phosphorus doping.

[0071] As a preferred technical proposal of the present invention, the manufacturing method includes the following processes in order:

[0072] Texturing process, diffusion process, laser doping process, chain oxidation process, PSG removal process, alkaline backside polishing process, annealing process, ALD passivation process, surface PECVD process, backside PECVD process, laser grooving process, screen printing process, and electroinjection process.

[0073] In this application, processes other than the diffusion process and the chain oxidation process employ general process methods, and their explanations are omitted.

[0074] The second object of this application is to provide an application of the method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter described in the first object, the manufacturing method of which is applied in the field of photovoltaic power generation.

[0075] Compared to the prior art, this invention has the following beneficial effects.

[0076] The conversion rate of the solar cell manufactured according to this invention was improved by 0.1% compared to conventional solar cells. [Brief explanation of the drawing]

[0077] [Figure 1] This is a graph of the phosphorus diffusion impurity distribution ECV in a specific embodiment of the present application. [Figure 2] The graphs show the diffusion impurity distribution ECV under two conditions in a specific embodiment of the present application. [Figure 3] This is a structural diagram of a chain oxidation furnace in a specific embodiment of the present invention. [Figure 4] This is a graph of high-temperature chain oxidation doping (with / without PSG layers) in a specific embodiment of the present invention. [Figure 5] This is a flowchart of the solar cell process in a specific embodiment of the present invention. [Figure 6] This is a graph of the doping profile in a specific embodiment of the present invention. [Figure 7] These are QE quantum efficiency diagrams for Example 1 and Comparative Example 1 of the present application. [Figure 8] This is a graph of the ECV doping concentration distribution for Example 1 and Comparative Example 1 according to the present application. [Modes for carrying out the invention]

[0078] The technical proposal of this application will be further described below with reference to specific embodiments. Those skilled in the art should understand that the above embodiments are merely for the purpose of understanding this application and should not be considered as specifically limiting it.

[0079] This application provides a method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter, including a diffusion process and a chain oxidation process.

[0080] The diffusion process includes low-temperature diffusion and high-temperature drive-in, and the chain oxidation process includes high-temperature chain oxidation.

[0081] This application analyzes influencing factors such as temperature, time, flow rate, and composition through DOE experiments of the diffusion process, revealing that important factors that alter the ECV curve of the diffusion process include surface concentration, emitter junction depth, complementary error distribution, and Gaussian doping profile curves. Next, the principle of high-temperature chain oxidation was understood, and its influence on surface doping during experiments was explored. Finally, by linking it to the principle of photovoltaic power generation in crystalline silicon solar cells, the diffusion process and chain oxidation process were combined to produce a diffusion emitter junction of approximately 0.15 μm, achieve good ohmic alloy contact with a high surface doping concentration, improve short-wave spectral absorption, and enhance the photoelectric conversion efficiency of the solar cell. This application demonstrates a significant inventive step.

[0082] This invention first optimizes the diffusion process to produce a shallow, low-doping diffusion bond with a depth of 0.15 μm, and then uses the photon thermal activation radiant energy of high-temperature chain oxidation to form a doping layer with a constant dose concentration on the surface of the diffusion layer, thereby solving the mismatch problem that would otherwise occur when forming ohmic contact between the silver paste and the alloy. Ultimately, a significant improvement in photoelectric conversion efficiency is achieved.

[0083] Furthermore, the diffusion process includes sequentially performing the following steps: entry into the boat, first heating, first constant temperature, vacuum stabilization, vacuum leak detection, oxidation, introduction of a first low-temperature diffusion source, introduction of a second low-temperature diffusion source, second heating, second constant temperature, high-temperature drive-in, first cooling, supplemental diffusion, purging, PSG deposition reaction, oxidation reaction, second cooling, nitrogen gas filling, and discharge from the boat.

[0084] Furthermore, the low-temperature diffusion includes diffusing a stationary source at a constant temperature.

[0085] Furthermore, the aforementioned fixation source is phosphorus oxychloride.

[0086] Furthermore, the low-temperature diffusion includes the introduction of a first low-temperature diffusion source and the introduction of a second low-temperature diffusion source.

[0087] Furthermore, the temperature at which the first low-temperature diffusion source is introduced is 770-790°C.

[0088] Furthermore, the time for introducing the first low-temperature diffusion source is 220-260 seconds.

[0089] Furthermore, the introduction of the first low-temperature diffusion source The first nitrogen The flow rate is 1000-1100 sccm.

[0090] Furthermore, the oxygen flow rate for the introduction of the first low-temperature diffusion source is 450-550 sccm.

[0091] Furthermore, the introduction of the first low-temperature diffusion source The second nitrogen The flow rate is 0 sccm.

[0092] Furthermore, the furnace tube pressure when the first low-temperature diffusion source is introduced is 50-60 mbar.

[0093] Furthermore, the temperature at which the second low-temperature diffusion source is introduced is 790-810°C.

[0094] Furthermore, the time for introducing the second low-temperature diffusion source is 190-230 seconds.

[0095] Furthermore, the introduction of the second low-temperature diffusion source The first nitrogen The flow rate is 1100-1200 sccm.

[0096] Furthermore, the oxygen flow rate for the introduction of the second low-temperature diffusion source is 550-650 sccm.

[0097] Furthermore, the introduction of the second low-temperature diffusion source The second nitrogen The flow rate is 0 sccm.

[0098] Furthermore, the furnace tube pressure when the second low-temperature diffusion source is introduced is 50-60 mbar.

[0099] In this application, during low-temperature diffusion, a fixed source amount (phosphorus oxychloride) is introduced at a temperature limited in this application, i.e., diffusion of the fixed source occurs, and the diffusion distribution curve at this time satisfies the complementary error distribution. The impurity distribution curve for phosphorus diffusion doping is constructed using low-temperature diffusion (complementary error distribution) and high-temperature drive-in (Gaussian distribution).

[0100] Here, the impurity distribution curve for phosphorus diffusion doping is shown in Figure 1. I represents PSG layer doping, which promotes SE laser doping, while high-temperature chain thermal oxidation allows thermal photon emission to activate doping. II represents surface layer doping, where high-concentration doping results in a dead layer due to lattice mismatch and reduces the short-wave response, while low-concentration doping affects the subsequent ohmic contact conduction of the screen. III is the junction depth curve, which affects the ohmic contact of the slurry and is related to light absorption.

[0101] Furthermore, the high-temperature drive-in includes driving a phosphorus source on the crystalline silicon surface into the silicon substrate at a high temperature.

[0102] Furthermore, the duration of the aforementioned high-temperature drive-in is 350-370 seconds.

[0103] Furthermore, the temperature of the aforementioned high-temperature drive-in is 800-900°C.

[0104] Furthermore, the high-temperature drive-in The first nitrogen The flow rate is 750-850 sccm.

[0105] Furthermore, the oxygen flow rate of the high-temperature drive-in is 0 sccm.

[0106] Furthermore, the high-temperature drive-in The second nitrogen The flow rate is 950-1050 sccm.

[0107] Furthermore, the furnace tube pressure in the aforementioned high-temperature drive-in is 50-60 mbar.

[0108] Furthermore, the temperature of the PSG deposition reaction is 700-800°C.

[0109] Furthermore, the duration of the PSG deposition reaction is 700-800 seconds.

[0110] Furthermore, phosphorus oxychloride is introduced into the PSG deposition reaction.

[0111] Furthermore, the PSG deposition reaction The first nitrogen The flow rate is 1250-1350 sccm.

[0112] Furthermore, the oxygen flow rate for the PSG deposition reaction is 550-650 sccm.

[0113] Furthermore, the PSG deposition reaction The second nitrogen The flow rate is 0 sccm.

[0114] Furthermore, the furnace tube pressure for the PSG deposition reaction is 55-65 mbar.

[0115] This invention creates a diffusion curve doping profile by controlling the amount of low-temperature diffusion source and the high-temperature drive-in time. As shown in Figure 2, this invention obtains a shallow emitter of about 0.15 μm. However, it was found that if the surface doping concentration of the diffusion curve is low, it causes subsequent failure of the alloy ohmic contact. Therefore, it is necessary to introduce high-temperature chain oxidation to activate surface doping.

[0116] Furthermore, the chain oxidation process includes entry into the oxidation chamber, high-temperature chain oxidation, and discharge from the oxidation chamber.

[0117] Furthermore, the temperature of the high-temperature chain oxidation is 660-670°C.

[0118] Furthermore, the duration of the high-temperature chain oxidation is 1 to 5 minutes.

[0119] Furthermore, the oxygen flow rate for the high-temperature chain oxidation is 95-105 slm.

[0120] Furthermore, the nitrogen gas flow rate for the high-temperature chain oxidation is 5 to 15 slm.

[0121] In this invention, heating is performed using a chain oxidation furnace as shown in Figure 3, with a large current and high power during heating. During the heating process of the halogen lamp, a large amount of high-energy electrons are emitted. When these high-energy electrons collide with the silicon wafer, the irradiated electrons interact with the lattice, disrupting the positions of atoms within the lattice, causing a displacement effect on the atoms, and simultaneously forming hole-interstitial atom pairs. At the same time, there are two types of phosphorus diffusion: interstitial diffusion and substitutional diffusion, and collisions of high-energy electrons reduce the difficulty of phosphorus diffusion. The chain oxidation device heats using an infrared halogen lamp, and when a stationary source is present on the surface of the silicon wafer, it triggers a diffusion enhancement mechanism, leading to a redistribution of the phosphorus source.

[0122] In this application, experiments revealed that the PSG doping layer shown in Figure 1-I is a surface phosphorus-activated doping source under chain oxidation conditions, and that different changes in surface concentration occurred in chain oxidation with and without the PSG layer. As shown in Figure 4, the cases with and without the PSG layer showed different surface doping concentrations in the ECV doping curve test after high-temperature chain oxidation. However, the doping curve after high-temperature chain oxidation with the PSG layer remaining is an important element in addressing the issue of surface doping affecting alloy ohmic contact.

[0123] Furthermore, the manufacturing method, as shown in Figure 5, includes the following processes in order.

[0124] Texturing process, diffusion process, laser doping process, chain oxidation process, PSG removal process, alkaline backside polishing process, annealing process, ALD passivation process, surface PECVD process, backside PECVD process, laser grooving process, screen printing process, and electroinjection process.

[0125] To further understand the method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter in this application, the following examples and comparative examples will be used for explanation.

[0126] Example 1 This embodiment provides a method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter.

[0127] The manufacturing method described above includes the following processes in order, as shown in Figure 5. Texturing process, diffusion process, laser doping process, chain oxidation process, PSG removal process, alkaline backside polishing process, annealing process, ALD passivation process, surface PECVD process, backside PECVD process, laser grooving process, screen printing process, and electroinjection process.

[0128] Here, the diffusion process includes the following steps. (1) The step of neatly inserting the crystalline silicon wafers that require diffusion into the quartz boat that enters the furnace tube, (2) Entering the boat step, the crystalline silicon wafer is fed into a high-temperature quartz furnace tube, and the time is set to 630 s, the temperature to 770°C, the flow rate of the nitrogen gas introduced to 2000 sccm, and the pressure to 1000 mbar, which is close to atmospheric pressure. (3) Wait for the furnace tube to heat up to the set temperature, set the time to 60 s, the temperature to 770°C, the nitrogen gas flow rate to 2000 sccm, and the vacuum pressure of the furnace tube to 700 mbar, and perform one pre-vacuum operation on the furnace tube in the first heating step. (4) Wait for the furnace tube to stabilize within the set temperature ±5°C range, and perform a vacuum operation on the furnace tube, setting the time to 180 s, the temperature to 770°C, the flow rate of the nitrogen gas to be introduced to 2000 sccm, and the furnace tube pressure to 55 mbar, First Nitrogen The first constant temperature step involves introducing a portion of the system (with phosphorus oxychloride closed) early to purge the pipeline and setting the flow rate to 500 sccm. (5) Vacuum stabilization step: Wait for the inside of the furnace tube to be drawn down to the set vacuum pressure, set the time to 60s, the temperature to 770°C, confine all gas introduction, and set the furnace tube pressure to 55mbar. (6) Vacuum leak detection step: Check whether a crack or seal failure has occurred in the furnace tube and whether an upward fluctuation in vacuum pressure has occurred, set the time to 60s, the temperature to 770°C, confine all gas introduction, and set the furnace tube pressure to 55mbar. (7) Before performing doping diffusion, in order to prevent corrosion to the surface of the crystalline silicon wafer during the subsequent reaction process of phosphorus oxychloride, it is necessary to grow a protective layer of silicon oxide on the surface of the crystalline silicon wafer for a time of 300 s and a temperature of 775°C. The first nitrogen The flow rate is 500 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 900 sccm. The second nitrogen Oxidation step: Set flow rate to 0 sccm and furnace tube pressure to 55 mbar. (8) The first phosphorus oxychloride diffusion doping reaction was carried out at a temperature of 775°C for a time of 240 s and a temperature of 775°C. The first nitrogen The flow rate is 1050 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 500 sccm. The second nitrogen The first cryogenic diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 55 mbar. (9) In order to activate the doping phosphorus source in the oxidizing layer by variable-temperature diffusion and to further homogenize the diffusion reaction, the temperature was adjusted to 795°C and the second phosphorus oxychloride diffusion doping reaction was carried out for a time of 210 s and a temperature of 795°C. The first nitrogen The flow rate is 1150 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 600 sccm. The second nitrogenThe second low-temperature diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 55 mbar. (10) A process in which the temperature is raised from 795°C to 850°C to complete the subsequent high-temperature doping drive-in reaction, while simultaneously introducing a large amount of nitrogen gas to remove some of the remaining phosphorus oxychloride and avoid safety risks, for a time of 300 s, and the temperature is raised to 850°C. The first nitrogen The flow rate is 800 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen The second heating step involves setting the flow rate to 1000 sccm and the furnace tube pressure to 55 mbar. (11) After the temperature has risen to the set temperature, it is necessary to stabilize it at a constant temperature for a certain period of time, and at the same time introduce a certain amount of oxygen gas to react with the remaining phosphorus oxychloride, avoiding safety risks, the time is 240s and the temperature is 850°C. The first nitrogen The flow rate is set to 500 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is set to 600 sccm. The second nitrogen The second constant temperature step involves setting the flow rate to 500 sccm and the furnace tube pressure to 55 mbar. (12) After reaching the set high temperature and ensuring that there is no reaction gas in the furnace tube, a high-temperature doping drive-in operation is performed to drive the phosphorus source on the surface of the crystalline silicon into the silicon substrate. In this step, time and temperature are important and directly affect the junction depth of the diffusion emitter. The time is set to 360 s and the temperature to 850°C. The first nitrogen The flow rate is 800 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen A high-temperature drive-in step with a flow rate of 1000 sccm and furnace tube pressure of 55 mbar. (13) As the setting temperature for supplemental diffusion, the temperature was lowered to about 800°C, the time was 1380 s, and the temperature was 790°C. The first nitrogen The flow rate is 800 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen The first cooling step involves setting the flow rate to 1000 sccm and the furnace tube pressure to 55 mbar. (14) To correct the phenomenon of insufficient doping in localized areas of crystalline silicon wafers due to high-temperature drive-in, the time was set to 90 s and the temperature to 790°C. The first nitrogen The flow rate is 1300 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 600 sccm. The second nitrogen A supplemental diffusion step in which the flow rate is set to 0 sccm and the furnace tube pressure to 60 mbar. (15) After diffusion is complete, the phosphorus oxychloride remaining in the furnace tube is completely removed by nitrogen gas and vacuum, with a time of 120 s and a temperature of 780°C. The first nitrogen The flow rate is 800 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen A purge step where the flow rate is set to 1000 sccm and the furnace tube pressure to 60 mbar. (16) A step that provides a sufficient phosphorus source for subsequent laser local doping, while also having the role of activating the phosphorus source in conjunction with subsequent high-temperature chain oxidation to form high doping on the surface, wherein the time is 760 s and the temperature is 750°C. The first nitrogen The flow rate is 1300 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 600 sccm. The second nitrogen PSG deposition reaction step: Set the flow rate to 0 sccm and the furnace tube pressure to 60 mbar. (17) Introduce a large amount of oxygen gas to thoroughly react the phosphorus oxychloride remaining in the furnace tubes, thereby avoiding the risk of leakage when the furnace door is opened afterward, set the time to 180 s and the temperature to 700°C. The first nitrogen The flow rate is 500 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 1500 sccm. The second nitrogen The oxidation reaction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 60 mbar. (18) A cooling step in which the temperature is set to a very low value with the aim of introducing a temperature change process to the crystalline silicon wafer after diffusion is complete, in which this process promotes the displacement of the crystal lattice, repairs lattice dislocation phenomena caused by some high-temperature diffusion, and further improves the quality of the diffusion emitter, the time is 360 s and the temperature is 700°C. The first nitrogen The flow rate is 1000 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen The second cooling step involves setting the flow rate to 0 sccm and the furnace tube pressure to 60 mbar. (19) After that, open the furnace door and prepare to take the crystalline silicon wafers by introducing a large amount of nitrogen gas into the furnace tubes to restore the atmospheric pressure in the furnace tubes, for a time of 240 s and a temperature of 700°C. The first nitrogen The flow rate is 1000 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen A nitrogen gas filling step in which the flow rate is set to 3000 sccm and the furnace tube pressure to 1000 mbar, and, (20) Open the furnace door and take out the quartz boat, terminate the entire diffusion process flow, set the time to 630s and the temperature to 750℃. The first nitrogen Flow rate 0 sccm, oxygen flow rate 0 sccm, The second nitrogen Discharge step from the boat, setting the flow rate to 2000 sccm and the furnace tube pressure to 1000 mbar.

[0129] Here, the chain oxidation process includes the following steps: (1) A step of placing a mounting case, which is a step of placing a mounting case containing a crystalline silicon wafer on an automated loader. (2) Steps to prepare the wafer for entry into the oxidation chamber, push the crystalline silicon wafer out of the mounting case and align it on the conveyor belt in front of the chain oxidation chamber, (3) Enter the high-temperature oxidation furnace chamber and set the belt speed to 3.8 m / min, the infrared halogen lamp temperature to 665°C, the flow rate of introduced oxygen to 100 slm, and the nitrogen gas flow rate to 10 slm. (4) The silicon wafers, having emerged from the oxidation chamber and completed high-temperature chain oxidation activation, are transported by a conveyor belt to the loading end and await being carried into the mounting case, and (5) The step of placing the crystalline silicon wafers, which have been placed in a mounting case and whose oxidation activation has been completed, into the mounting case one by one from the conveyor belt, completing the mounting, and then sending them to the subsequent PSG removal process.

[0130] Example 2 In this example, step (8) in the diffusion process was replaced with the following step: The first phosphorus oxychloride diffusion doping reaction was carried out at a temperature of 770°C for a time of 260 s and a temperature of 770°C. The first nitrogen The flow rate is set to 1000 sccm (with phosphorus oxychloride open), and the oxygen flow rate is set to 450 sccm. The second nitrogen A first cryogenic diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 50 mbar. Step (9) in the diffusion process was replaced with the following step: The temperature was adjusted to 790°C to activate the doping phosphorus source in the oxide layer by thermochromic diffusion and to further homogenize the diffusion reaction, and a second phosphorus oxychloride diffusion doping reaction was performed for 230 s and at a temperature of 790°C. The first nitrogen The flow rate is 1100 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 550 sccm. The second nitrogen A second cryogenic diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 50 mbar. Step (12) in the diffusion process was replaced with the following step: After reaching the set high temperature and ensuring that there is no reaction gas in the furnace tube, a high-temperature doping drive-in operation is performed to drive the phosphorus source on the crystalline silicon surface into the silicon substrate. In this step, time and temperature are important and directly affect the junction depth of the diffusion emitter, and the time was set to 370 s and the temperature to 800°C. The first nitrogen The flow rate is 750 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen A high-temperature drive-in step with a flow rate of 950 sccm and furnace tube pressure of 50 mbar. Step (16) in the diffusion process was replaced with the following step: a step that provides a sufficient phosphorus source for subsequent laser local doping, while also having the important finding of this patent, which allows the phosphorus source to be activated in conjunction with subsequent high-temperature chain oxidation to form high doping on the surface, with a time of 800 s and a temperature of 700°C. The first nitrogen The flow rate is 1250 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 550 sccm. The second nitrogen A PSG deposition reaction step in which the flow rate is set to 0 sccm and the furnace tube pressure to 55 mbar. Step (3) in the chain oxidation process was replaced with the following step: enter the high-temperature oxidation furnace chamber and set the belt speed to 3.8 m / min, the infrared halogen lamp temperature to 660°C, the flow rate of introduced oxygen to 95 slm, and the nitrogen gas flow rate to 5 slm.

[0131] Other conditions are the same as in Example 1.

[0132] Example 3 In this example, step (8) in the diffusion process was replaced with the following step: The first phosphorus oxychloride diffusion doping reaction was carried out at a temperature of 790°C for a time of 220 s and a temperature of 790°C. The first nitrogen The flow rate is 1100 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 550 sccm. The second nitrogen A first cryogenic diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 60 mbar. Step (9) in the diffusion process was replaced with the following step: The temperature was adjusted to 810°C to activate the doping phosphorus source in the oxide layer by variable-temperature diffusion and to further homogenize the diffusion reaction, and a second phosphorus oxychloride diffusion doping reaction was performed for 190 s and at a temperature of 1200°C. The first nitrogen The flow rate is 650 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 650 sccm. The second nitrogen A second low-temperature diffusion source introduction step involves setting the flow rate to 0 sccm and the furnace tube pressure to 60 mbar. Step (12) in the diffusion process was replaced with the following step: After reaching the set high temperature and ensuring that there is no reaction gas in the furnace tube, a high-temperature doping drive-in operation is performed to drive the phosphorus source on the crystalline silicon surface into the silicon substrate. In this step, time and temperature are important and directly affect the junction depth of the diffusion emitter, and the time was set to 350 s and the temperature to 900°C. The first nitrogen The flow rate is 850 sccm (with the phosphorus oxychloride valve closed), and the oxygen flow rate is 0 sccm. The second nitrogen A high-temperature drive-in step with a flow rate of 1050 sccm and furnace tube pressure of 60 mbar. Step (16) in the diffusion process was replaced with the following step: a step that provides a sufficient phosphorus source for subsequent laser local doping, while also having the important finding of this patent, which allows the phosphorus source to be activated in conjunction with subsequent high-temperature chain oxidation to form high doping on the surface, with a time of 700 s and a temperature of 800°C. The first nitrogen The flow rate is 1350 sccm (with phosphorus oxychloride open), and the oxygen flow rate is 650 sccm. The second nitrogen A PSG deposition reaction step in which the flow rate is set to 0 sccm and the furnace tube pressure to 65 mbar. Step (3) in the chain oxidation process was replaced with the following steps: entering the high-temperature oxidation furnace chamber, setting the belt speed to 3.8 m / min, the infrared halogen lamp temperature to 670°C, the flow rate of introduced oxygen to 105 slm, and the nitrogen gas flow rate to 15 slm.

[0133] Other conditions are the same as in Example 1.

[0134] Example 4 In this embodiment, all other conditions are the same as in Example 1, except that the temperature of the first low-temperature diffusion source introduction step (8) in the diffusion process is replaced with 700°C.

[0135] Example 5 In this example, all other conditions are the same as in Example 1, except that the temperature of the high-temperature drive-in step in step (12) of the diffusion process is set to 950°C.

[0136] Example 6 In this example, all other conditions are the same as in Example 1, except that the infrared halogen lamp temperature in the high-temperature chain oxidation process was changed from 665°C to 700°C.

[0137] Example 7 In this embodiment, all other conditions are the same as in Example 1, except for the introduction of the second low-temperature diffusion source in step (9) of the diffusion process.

[0138] Example 8 In this example, all other conditions are the same as in Example 1, except for the PSG deposition reaction step (16) in the diffusion process.

[0139] Comparative Example 1 In this comparative example, all other conditions are the same as in Example 1, except that chain oxidation is replaced with conventional high-temperature tube oxidation.

[0140] Comparative Example 2 In this comparative example, all other conditions are the same as in Example 1, except for the high-temperature drive-in step (12) in the diffusion process.

[0141] Comparative Example 3 In this comparative example, all other conditions are the same as in Example 1, except that the chain oxidation step is replaced with a room-temperature chain oxidation step.

[0142] Several mass production runs were carried out in Example 1 and Comparative Example 1 of this application, and the results are shown in Table 1. [Table 1]

[0143] As can be seen from the table above, by manufacturing a shallow junction diffusion emitter according to this invention, the conversion efficiency of crystalline silicon solar cells was improved by 0.1%, mainly by improving the open-circuit voltage Uoc and short-circuit current Isc.

[0144] Here, the doping profile curves for Example 1 and Comparative Example 1 in this application are shown in Figure 6, the quantum efficiency (QE) graph is shown in Figure 7, and the ECV (electrolytic corrosion) doping concentration distribution graph is shown in Figure 8. As can be seen from the quantum efficiency (QE) graph in Figure 7, the short-wave spectral response in the 300 nm to 500 nm range was clearly higher for Example 1 than for Comparative Example 1. As can be seen from Figure 8, the junction depth of Example 1 in this application was 0.15 μm, and the surface concentration was 1.0 × 10⁻⁶ μm. 21 cm -3 In all cases, the results are superior to those of Comparative Example 1.

[0145] Solar cells from Examples 1-8 and Comparative Examples 1-3 were produced on a production line, and the test results are shown in Table 2. [Table 2]

[0146] As can be seen from the table above, the efficiency improvement in Examples 1-3 is clear, and the efficiency improved by about 0.1%, with consistent results. In Example 4, the temperature of the introduction of the first low-temperature diffusion source was replaced with a lower temperature; in Example 5, the temperature of the high-temperature drive-in in the diffusion process was increased; in Example 6, the temperature of the high-temperature chain oxidation was further increased; and in Example 7, the second low-temperature diffusion source introduction process was excluded. In all of Examples 4-6, the photoconversion efficiency decreased compared to Example 1. In Comparative Example 1, chain oxidation was replaced with high-temperature tube oxidation; in Comparative Example 2, the high-temperature drive-in step was excluded; and in Comparative Example 3, high-temperature chain oxidation was replaced with room-temperature chain oxidation, and it was observed that the photoconversion efficiency of the solar cell further decreased.

[0147] The above describes only specific embodiments of the present application, but the applicant declares that the scope of protection of this application is not limited thereto. A person skilled in the art should understand that any modification or substitution that such a person can easily foresee within the technical scope disclosed in this application falls within the scope of protection and disclosure of this application.

Claims

1. A method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter, comprising a diffusion process and a chain oxidation process, The chain oxidation process is carried out after the diffusion process. The bonding depth of the aforementioned shallow bond is 0.1 μm to 0.2 μm. In the aforementioned chain oxidation process, a chain oxidation furnace is used, The diffusion process includes low-temperature diffusion and high-temperature drive-in, and the chain oxidation process includes high-temperature chain oxidation. A method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter, comprising the diffusion process of sequentially performing the following steps: entry into a boat, first heating, first constant temperature, vacuum stabilization, vacuum leak detection, oxidation, introduction of a first low-temperature diffusion source, introduction of a second low-temperature diffusion source, second heating, second constant temperature, high-temperature drive-in, first cooling, supplemental diffusion, purging, PSG deposition reaction, oxidation reaction, second cooling, nitrogen gas filling, and discharge from the boat.

2. The aforementioned low-temperature diffusion includes diffusing a stationary source at a constant temperature. The manufacturing method according to claim 1, wherein the fixation source is phosphorus oxychloride.

3. The low-temperature diffusion includes the introduction of a first low-temperature diffusion source and the introduction of a second low-temperature diffusion source. The temperature at which the first low-temperature diffusion source is introduced is 770 to 790°C. The time for introducing the first low-temperature diffusion source is 220 to 260 seconds. The flow rate of the first nitrogen introduced by the first low-temperature diffusion source is 1000 to 1100 sccm. The oxygen flow rate for the introduction of the first low-temperature diffusion source is 450 to 550 sccm. The flow rate of the second nitrogen introduced by the first low-temperature diffusion source is 0 sccm. The furnace tube pressure when the first low-temperature diffusion source is introduced is 50-60 mbar. The temperature at which the second low-temperature diffusion source is introduced is 790 to 810°C. The time for introducing the second low-temperature diffusion source was 190 to 230 seconds. The flow rate of the first nitrogen introduced by the second low-temperature diffusion source is 1100 to 1200 sccm. The oxygen flow rate for the introduction of the second low-temperature diffusion source is 550 to 650 sccm. The flow rate of the second nitrogen introduced by the second low-temperature diffusion source is 0 sccm. The manufacturing method according to claim 1, wherein the furnace tube pressure for introducing the second low-temperature diffusion source is 50 to 60 mbar.

4. The aforementioned high-temperature drive-in includes driving a phosphorus source on the crystalline silicon surface into the silicon substrate at a high temperature. The duration of the aforementioned high-temperature drive-in is 350 to 370 seconds. The temperature of the aforementioned high-temperature drive-in is 800 to 900°C. The first nitrogen flow rate of the aforementioned high-temperature drive-in is 750 to 850 sccm. The oxygen flow rate of the aforementioned high-temperature drive-in is 0 sccm. The flow rate of the second nitrogen in the aforementioned high-temperature drive-in is 950 to 1050 sccm. The manufacturing method according to claim 1, wherein the furnace tube pressure of the high-temperature drive-in is 50 to 60 mbar.

5. The temperature of the PSG deposition reaction is 700 to 800°C. The duration of the PSG deposition reaction is 700 to 800 s. The aforementioned PSG deposition reaction involves introducing phosphorus oxychloride, The first nitrogen flow rate in the aforementioned PSG deposition reaction is 1250 to 1350 sccm. The oxygen flow rate for the aforementioned PSG deposition reaction is 550-650 sccm. The flow rate of the second nitrogen in the PSG deposition reaction is 0 sccm. The manufacturing method according to claim 1, wherein the furnace tube pressure for the PSG deposition reaction is 55 to 65 mbar.

6. The manufacturing method according to claim 1, wherein a vacuum treatment is performed on the furnace tube during the first heating and first constant temperature.

7. The manufacturing method according to claim 1, wherein, at the first constant temperature, a first nitrogen is introduced to purge the pipeline, and the flow rate of the purge is 450 to 550 sccm.

8. The manufacturing method according to claim 1, wherein after the pressure stabilizes during the vacuum stabilization, all gas introduction is closed and the pressure in the furnace tube is maintained at 50 to 60 mbar.

9. The manufacturing method according to claim 1, wherein the oxidation includes providing protection for the growth of a single silicon oxide layer on the surface of a crystalline silicon wafer.

10. The temperature reached during the second heating process is 830 to 870°C. During the second heating step, nitrogen gas is introduced to remove any remaining phosphorus oxychloride. The manufacturing method according to claim 1, wherein, in the second heating, the flow rate of the second nitrogen is 950 to 1050 sccm.

11. At the second constant temperature, oxygen is introduced to allow the remaining phosphorus oxychloride to react further. The manufacturing method according to claim 1, wherein the oxygen flow rate is 550 to 650 sccm at the second constant temperature.

12. The temperature of the first cooling process is 750 to 810°C. The aforementioned supplementation diffusion is used to repair the defect of insufficient doping in localized areas of crystalline silicon wafers due to high-temperature drive-in. The aforementioned purge removes phosphorus oxychloride remaining in the furnace tubes. The aforementioned oxidation reaction removes the phosphorus oxychloride introduced into the PSG deposition reaction. The second cooling process is used to repair lattice dislocations in the crystalline silicon wafer. The manufacturing method according to claim 1, wherein the nitrogen gas filling is used to restore the furnace tube to an atmospheric pressure state.

13. The chain oxidation process includes high-temperature chain oxidation. The temperature of the aforementioned high-temperature chain oxidation is 660 to 670°C. The duration of the aforementioned high-temperature chain oxidation is 1 to 5 minutes. The oxygen flow rate for the aforementioned high-temperature chain oxidation is 95 to 105 slm. The manufacturing method according to claim 1, wherein the nitrogen gas flow rate for the high-temperature chain oxidation is 5 to 15 slm.

14. The aforementioned manufacturing method is The manufacturing method according to claim 1, comprising, in the order of process, a texturing process, the diffusion process, a laser doping process, the chain oxidation process, a PSG removal process, an alkaline backside polishing process, an annealing process, an ALD passivation process, a frontside PECVD process, a backside PECVD process, a laser grooving process, a screen printing process, and an electroinjection process.

15. Use of a method for manufacturing a crystalline silicon solar cell with a shallow junction diffusion emitter according to any one of claims 1 to 14, which is applied in the field of photovoltaic power generation.

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