A Passivation Method for Boron- and Phosphorus-Doped Poly Layers, Its Passivated Contact Structure and Battery

Abstract

The present invention discloses a passivation method for boron- and phosphorus-doped Poly layers, as well as a passivation contact structure and a battery thereof. The passivation method first grows a tunneling oxide layer with thin and dense sides and thick and porous middle on the silicon wafer surface by combining low-temperature and low-pressure oxidation, high-temperature and atmospheric-pressure oxidation, and low-temperature and atmospheric-pressure oxidation, and then uses a high-temperature diffusion tube for deposition and oxidation promotion of boron atoms and / or phosphorus atoms, so that a certain concentration of boron and phosphorus is doped in the Poly silicon layer. By superimposing different dense oxide layers, the present invention improves the overall thickness of the tunneling oxide layer, so that the structure of the tunneling oxide layer is not significantly damaged during the subsequent boron and phosphorus diffusion processes, and significantly improves the passivation effect of the boron- and phosphorus-doped Poly layer. The passivation method of the present invention can obtain Poly silicon layers and doped polysilicon layers with different thicknesses, and can be applied to all batteries that require the use of boron Poly and phosphorus Poly.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and particularly relates to a passivation method for a boron- and phosphorus-doped Poly layer, a passivated contact structure, and a battery thereof. Background Art

[0002] The passivation effect has a direct impact on the photoelectric conversion efficiency of solar cells. When sunlight irradiates a cell, two types of carriers are excited inside the cell: negatively charged electrons and positively charged holes. During the production of solar cell wafers, it is necessary to minimize the defects inside the wafers and the interface state density on each surface, enhance the passivation effect, thereby reducing the recombination of electrons and holes inside the solar cell wafers, reducing internal consumption, and enabling as many carriers as possible to reach the positive and negative electrodes of the battery, thereby increasing the photoelectric conversion efficiency of the battery.

[0003] In the manufacture of solar cells, boron- and phosphorus-doped Poly (polycrystalline silicon structure with a tunneling oxide layer doped with boron and phosphorus) passivation is a common surface treatment method.

[0004] For the boron diffusion on N-type silicon in the boron-doped Poly layer, the boron atoms entering the monocrystalline silicon substrate will form a PN junction with the N-type silicon substrate. One aspect of its passivation mechanism is that the PN junction can screen out holes to pass through the PN junction while blocking electrons, thereby forming an environment where the number of holes dominates on one side of the PN junction and the number of electrons dominates on the other side, thereby reducing the recombination annihilation of holes and electrons at defects. On the other hand, there are a large number of defects at the junction of the monocrystalline silicon and the Poly layer. Growing a dense tunneling oxide layer in the middle of the two interfaces can significantly reduce the interface state density, so that the recombination of holes passing through the tunneling oxide layer is small. The tunneling oxide layer and the PN junction work together, so that the boron Poly has a good passivation effect. Generally, the composite current density (the magnitude of the composite current per unit area) is used to characterize the passivation effect. The smaller the composite current density, the better the surface passivation effect.

[0005] The passivation mechanism of the phosphorus-doped Poly layer is similar. There are a high concentration of phosphorus atoms in the Poly layer, and at the same time, some phosphorus atoms will pass through the tunneling oxide layer to form a high-low junction structure with the N-type substrate, resulting in band bending near the tunneling oxide layer. On the one hand, it reduces the number of minority carriers (holes) near the tunneling oxide layer and reduces recombination. On the other hand, it can screen out majority carriers (electrons) to selectively pass through the tunneling oxide layer, thereby greatly enhancing the passivation effect.

[0006] Currently, the commonly used passivation method for boron- and phosphorus-doped Poly layers is to place the silicon wafer in a quartz furnace tube and introduce oxygen in an environment above 600 °C. Oxygen directly reacts with the silicon on the surface of the silicon wafer at high temperature to form a silicon oxide film (tunneling oxide layer) with a thickness of 1 - 2 nm. Then, a Poly silicon layer (polycrystalline silicon layer) is directly deposited on this tunneling oxide layer. Next, it is placed in a high-temperature diffusion furnace tube for deposition and oxidation promotion steps. Finally, it is cooled to room temperature to obtain the desired boron Poly or phosphorus Poly structure. However, the passivation effect of the Poly obtained by this method is not very good, and the recombination current density is relatively high; especially the recombination current density of boron Poly is above 15 fA / cm 2 Above. Moreover, when using this passivation method, since the tunneling oxide layer of the boron- and phosphorus-doped Poly layer is directly grown by high-temperature oxidation and is relatively loose, the passivation effect is not good. When the boron and phosphorus doping concentrations are high, it is easy to cause serious internal diffusion, and it is also greatly affected by the subsequent processes, making it impossible to form a better morphology structure; it cannot meet the requirements of complex-structured batteries (such as BC-structured batteries) that require secondary processing on the Poly layer. Summary of the Invention

[0007] Aiming at the problem of poor passivation effect of boron- and phosphorus-doped Poly layers caused by the existing direct high-temperature growth of tunneling oxide layers, the purpose of the present invention is to provide a passivation method for boron- and phosphorus-doped Poly layers, a passivation contact structure, and a battery that optimize the passivation effect based on the LPCVD process.

[0008] The present invention achieves the above technical effects through the following technical solutions.

[0009] In a first aspect, the passivation method for boron- and phosphorus-doped Poly layer provided by the present invention includes the following steps: S1. Provide a clean and polished silicon wafer. Using an LPCVD device, evacuate the air, introduce oxygen, and perform a first oxidation on the silicon wafer at a low temperature and low pressure below 600 °C to grow a first oxide layer with a thickness of 0.3 - 0.8 nm and dense on the surface of the silicon wafer; S2. Raise the temperature in step S1 by 50 - 220 °C, continuously introduce oxygen, and perform a second oxidation on the silicon wafer at a pressure greater than or equal to 1 standard atmospheric pressure to continue growing a second oxide layer with a thickness of 0.5 - 1 nm and loose on the surface of the silicon wafer; S3. Stop introducing oxygen, keep the pressure unchanged, lower the temperature to below 600 °C, and perform a third oxidation on the silicon wafer to continue growing a third oxide layer with a thickness of 0.1 - 0.4 nm and dense on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a loose middle and dense sides is grown on the surface of the silicon wafer; S4. Continue to use the LPCVD device, raise the temperature in step S3 by 0 - 50 °C, evacuate the air and then introduce silane, and deposit a polysilicon layer on the first oxide layer at a high temperature and low pressure until the film thickness required by the process is reached; S5. Use a high-temperature diffusion tube to deposit and oxidize and push boron atoms or phosphorus atoms to dope a certain concentration of boron or phosphorus in the polysilicon layer to form a doped polysilicon layer.

[0010] Preferably, in step S1, the temperature is 400 - 590 °C, the pressure is 0.1 - 0.5 standard atmospheric pressure, and the first oxidation time is 10 - 20 minutes.

[0011] Further, in step S2, the temperature is 610 - 640 °C, the pressure is normal pressure, and the second oxidation time is 10 - 20 minutes.

[0012] Further, in step S3, the temperature is 550 - 590 °C, the pressure is normal pressure, and the third oxidation time is 10 - 20 minutes.

[0013] Further, in step S4, the temperature is 550 - 640 °C, and the vacuum pressure is 180 - 300 mTorr.

[0014] Further, the silicon wafer is an N-type silicon wafer or a P-type silicon wafer.

[0015] Further, in steps S1 and S2, the flow rate of the introduced oxygen is 5 - 30 L / min.

[0016] In step S5, boron atoms are deposited and the oxidation push-in process (boron diffusion) is performed at a deposition temperature of 800-850°C, and the oxidation push-in temperature is 940-1000°C, with the optimal oxidation push-in temperature being 960°C. Phosphorus atoms are deposited and the oxidation push-in process (phosphorus diffusion) is performed at a deposition temperature of 800-850°C, and the oxidation push-in temperature is 880-920°C. The tunneling oxide layer is grown by combining low-temperature, low-pressure oxidation, high-temperature, atmospheric-pressure oxidation, and low-temperature, atmospheric-pressure oxidation. Subsequent fluctuations in the boron and phosphorus diffusion oxidation temperatures are minimal, and fluctuations of 30°C above the optimal oxidation push-in temperature are generally acceptable.

[0017] In second aspect, the present invention provides a passivation contact structure of a boron and phosphorus doped Poly layer, the passivation contact structure comprising a first oxide layer, a second oxide layer, a third oxide layer and a doped polysilicon layer grown on a silicon wafer using the aforementioned passivation method, the doped polysilicon layer being above the first oxide layer, the first oxide layer, the second oxide layer and the third oxide layer constituting a tunneling oxide layer, the doped polysilicon layer and the second oxide layer being located in the middle of the tunneling oxide layer, being thick and loose; the first oxide layer and the third oxide layer being located on both sides of the tunneling oxide layer, being thin and dense.

[0018] In a third aspect, the present invention provides a battery having a passivation contact structure of a boron- and phosphorus-doped Poly layer, the battery comprising a silicon wafer and the passivation contact structure as described above formed on the surface of the silicon wafer.

[0019] Furthermore, the battery is a TOPCon battery, a TBC battery or a perovskite stacked battery.

[0020] Compared with the prior art, the present invention has the following beneficial effects.

[0021] The present invention adopts a method of combining low-temperature and low-pressure oxidation, high-temperature and normal-pressure oxidation, and low-temperature and normal-pressure oxidation to grow a tunneling oxide layer. The film structure of the generated tunneling oxide layer is a stacked structure with thin and dense layers on both sides and thick and loose layers in the middle. By superimposing oxide layers with different densities, the passivation effect of the boron and phosphorus doped Poly layer structure is improved.

[0022] The thin and dense oxide layers on both sides are grown at low temperature, and have fewer interface defects in contact with the Poly silicon layer. This can significantly reduce the interface state density at the junction of the oxide layer and silicon, reduce the recombination of carriers reaching the interface, and significantly improve the passivation effect.

[0023] Meanwhile, the second oxide layer grown at high temperature is thick and porous. It can not only increase the overall thickness of the tunneling oxide layer (although the total thickness of the three stacked oxide layers is approximately equal to that of a conventional tunneling oxide layer), but also provide channels for impurity atoms to pass through the tunneling oxide layer during subsequent boron diffusion (doping) and / or phosphorus diffusion (doping) to form a PN junction, thus preventing the tunneling oxide layer from being significantly damaged and further enhancing the passivation effect.

[0024] Compared with the boron- and phosphorus-doped Poly layers of traditional direct high-temperature oxidation processes, the minority carrier lifetime, iVoc, iFF, and PL brightness are significantly improved, and the recombination current density J0 is significantly reduced when using the passivation method of the present invention, showing a better passivation effect.

[0025] The passivation method of the present invention can achieve a good passivation effect by optimizing parameters such as the pressure, temperature, and time of the LPCVD equipment. The required structure can be obtained in one process. Compared with other passivation methods such as annealing, hydrogen implantation, and adding laminated layers of different materials, the process time is short, less special gas is used, and the production cost can be effectively reduced.

[0026] The passivation contact structure grown by the passivation method of the present invention has good robustness. When the parameters such as the temperature and gas flow of the high-temperature furnace tube fluctuate slightly during the use of the LPCVD equipment, the passivation effect of the boron- and phosphorus-doped Poly layers will not be significantly affected. The tunneling oxide layer grown by the present invention is less affected by the temperature fluctuations of boron and phosphorus diffusion oxidation and can tolerate a 30°C fluctuation above the optimal oxidation rate temperature.

[0027] When the passivation contact structure grown by the passivation method of the present invention is applied to the preparation of a battery with a complex secondary processed structure (such as a BC structure battery) that requires a boron- and phosphorus-doped Poly layer, the subsequent laser process will not have a great impact on the structure of the tunneling oxide layer, and the plane after wet etching is flatter, enabling a better morphological structure to be formed.

[0028] The passivation method of the present invention can obtain Poly silicon layers and doped polycrystalline silicon layers with different required thicknesses. The boron- or phosphorus-doped Poly layer has excellent passivation performance and can be applied to all batteries that require the use of boron Poly or phosphorus Poly. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 Schematic diagram of the passivation contact structure of the present invention.

[0031] Figure 2 Depth-concentration comparison diagram of the boron-doped Poly layer of the present invention and the prior art.

[0032] Figure 3 Schematic diagram of the TOPCon cell structure.

[0033] Figure 4 Schematic diagram of the TBC cell structure.

[0034] Figure 5 Depth-concentration comparison diagram of the boron-doped Poly layer after laser film removal and cleaning film removal.

[0035] Figure 6 Backside scanning electron microscope image of the BC structure cell prepared by using the passivation method of the present invention.

[0036] In the figure: 1 - silicon wafer, 2 - first oxide layer, 3 - second oxide layer, 4 - third oxide layer, 5 - doped polysilicon layer. Detailed implementation manners

[0037] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific implementation manners. It should be understood that the implementation manners described here are part of the implementation manners of the present invention, rather than all of the implementation manners, and are only used to explain the present invention, not to limit the present invention. Based on the implementation manners in the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0038] In a first aspect, a passivation method for a boron- and phosphorus-doped Poly layer provided by the present invention includes the following steps: S1. Provide a clean and polished silicon wafer. Using an LPCVD device, evacuate the air, introduce oxygen, and perform a first oxidation on the silicon wafer at a low temperature and low pressure below 600°C to grow a thin and dense first oxide layer on the surface of the silicon wafer; S2. Raise the temperature in step S1 by 50-220°C, continuously introduce oxygen, and perform a second oxidation on the silicon wafer at a pressure greater than or equal to 1 standard atmospheric pressure to continuously grow a thick and porous second oxide layer on the surface of the silicon wafer; S3. Stop introducing oxygen, keep the pressure unchanged, lower the temperature to below 600°C, and perform a third oxidation on the silicon wafer to continuously grow a thin and dense third oxide layer on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a porous middle and dense sides is grown on the surface of the silicon wafer; S4. Continue to use the LPCVD device, raise the temperature in step S3 by 0-50°C, introduce silane, and evacuate the air at the same time. Deposit a polysilicon layer on the first oxide layer at a high temperature and low pressure until the film thickness required by the process is reached; S5. Use a high-temperature diffusion tube to deposit and oxidize and promote boron atoms or phosphorus atoms, so that a certain concentration of boron or phosphorus is doped in the polysilicon layer to form a doped polysilicon layer.

[0039] As a preferred embodiment, in step S1, the temperature is 400-590°C, the pressure is 0.1-0.5 standard atmospheric pressure, the first oxidation time is 10-20 minutes, and the thickness of the first oxide layer is 0.3-0.8 nm. Specifically, the temperature of the first oxidation can be 400°C, 430°C, 460°C, 490°C, 500°C, 520°C, 550°C, 570°C or 590°C, etc.; further preferably 500-580°C. The first oxidation time can be 10 minutes, 14 minutes, 16 minutes, 18 minutes, or 20 minutes, etc. The thickness of the first oxide layer can be 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm or 0.8 nm, etc., and further preferably 0.3-0.5 nm. In this way, a thin and dense tunneling oxide layer can be generated by low-temperature and low-pressure oxidation.

[0040] As a preferred embodiment, in step S2, the temperature is 610-640°C, the pressure is normal pressure, the second oxidation time is 10-20 minutes, and the thickness of the second oxide layer is 0.5-1 nm. Specifically, the temperature of the second oxidation can be 610°C, 620°C, 625°C, 632°C or 640°C, etc. The second oxidation time can be 10 minutes, 14 minutes, 16 minutes, 18 minutes, or 20 minutes, etc. The thickness of the second oxide layer can be 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, or 1 nm, etc. In this way, a thick and porous tunneling oxide layer can be generated by high-temperature and normal-pressure oxidation.

[0041] As a preferred embodiment, in step S3, the temperature is 550 - 590 °C, the pressure is atmospheric pressure, the third oxidation time is 10 - 20 minutes, and the thickness of the third oxide layer is 0.1 - 0.4 nm. Specifically, the temperature of the third oxidation can be 550 °C, 560 °C, 570 °C, 580 °C, or 590 °C, etc. The third oxidation time can be 10 minutes, 14 minutes, 16 minutes, 18 minutes, or 20 minutes, etc. The thickness of the third oxide layer can be 0.1 nm, 0.18 nm, 0.25 nm, 0.3 nm, 0.35 nm, or 0.4 nm, etc. In this way, a thin and dense tunneling oxide layer can be formed by low-temperature atmospheric oxidation.

[0042] As a preferred embodiment, in step S4, the temperature is 550 - 640 °C, specifically, it can be 550 °C, 560 °C, 570 °C, 580 °C, 590 °C, 600 °C, 610 °C, 620 °C, 630 °C, or 640 °C, etc.; the vacuum pressure is 180 - 300 mTorr, specifically, it can be 180 mTorr, 200 mTorr, 220 mTorr, 250 mTorr, 280 mTorr, or 300 mTorr, etc. In this way, polysilicon layers with different thicknesses can be deposited on the tunneling oxide layer.

[0043] As a preferred embodiment, the silicon wafer is an N-type silicon wafer or a P-type silicon wafer. The passivation method of the present invention is applicable not only to N-type silicon wafers but also to P-type silicon wafers.

[0044] As a preferred embodiment, in steps S1 and S2, the flow rate of oxygen introduced is 5 - 30 L / min. In this way, the thickness of the oxide layer required for forming the passivation contact can be satisfied.

[0045] The oxygen flow rate can control the time for the furnace tube to change from vacuum to atmospheric pressure. Low-pressure oxidation is similar to low-temperature oxidation in that both can form a denser tunneling oxide layer. It is best to introduce oxygen slowly in step S1 to allow low-temperature and low-pressure growth.

[0046] In step S3, there is no need to introduce oxygen, and the existing oxygen in the tube can be used for continuous oxidation.

[0047] As a preferred embodiment, during the deposition and oxidation push process (boron diffusion) of boron atoms, the deposition temperature is 800 - 850 °C, the oxidation push temperature is 940 - 1000 °C, and the optimal oxidation push temperature is 960 °C; during the deposition and oxidation push process (phosphorus diffusion) of phosphorus atoms, the deposition temperature is 800 - 850 °C, and the oxidation push temperature is 880 - 920 °C.

[0048] Specifically, during the boron diffusion process, boron trichloride and oxygen are introduced, initially deposited at 800-850°C for 600-1500 seconds, then heated to 940-1000°C, and further oxygen is introduced for at least 20 minutes. During the phosphorus diffusion process, phosphorus oxychloride and oxygen are introduced, initially deposited at 800-850°C for 600-1500 seconds, then heated to 880-920°C, and further oxygen is introduced for 10-20 minutes. The specific deposition amount, oxidation time, and temperature depend primarily on the LP process.

[0049] The oxidation push temperature significantly affects diffusion. However, the present invention utilizes a combination of low-temperature, low-pressure oxidation, high-temperature, normal-pressure oxidation, and low-temperature, normal-pressure oxidation to grow the tunnel oxide layer. This reduces the impact of subsequent boron and phosphorus diffusion temperature fluctuations, allowing for a 30°C fluctuation above the optimal oxidation push temperature.

[0050] After the heteroatom diffusion, the doping concentration corresponding to different depths of the silicon wafer can be obtained by the ECV test machine. Figure 2 From the comparison in the figure, it can be seen that compared with the prior art high-temperature oxidation growth of a loose tunnel oxide layer, the boron-doped Poly layer of the present invention can reduce the internal expansion while obtaining a higher doping concentration (the faster the decline, the smaller the internal expansion), thereby improving the passivation performance.

[0051] In a second aspect, the present invention provides a passivation contact structure of a boron and phosphorus doped Poly layer, such as Figure 1 As shown, the passivation contact structure includes a first oxide layer 2, a second oxide layer 3, a third oxide layer 4 and a doped polysilicon layer 5 grown on a silicon wafer 1 using the aforementioned passivation method, wherein the doped polysilicon layer 5 is on the first oxide layer 2, and the first oxide layer 2, the second oxide layer 3 and the third oxide layer 4 constitute a tunneling oxide layer, wherein the second oxide layer 3 is located in the middle of the tunneling oxide layer and is thick and loose; the first oxide layer 2 and the third oxide layer 4 are located on both sides of the tunneling oxide layer and are thin and dense.

[0052] In a third aspect, the present invention provides a battery having a passivation contact structure of a boron- and phosphorus-doped Poly layer, the battery comprising a silicon wafer and the passivation contact structure as described above formed on the surface of the silicon wafer.

[0053] As a preferred embodiment, the cell is a TOPCon cell, a TBC cell or a perovskite stack cell.

[0054] The passivation method of the present invention can obtain the required Poly silicon layer and doped polysilicon layer of different thicknesses. The boron and phosphorus doped Poly layer has excellent passivation performance and can be applied to all batteries that need to use boron Poly and phosphorus Poly. Figure 3As shown, by using the passivation method of the present invention, a tunneling oxide layer structure with a loose middle and dense sides can be grown in the N region of the TOPCon cell structure, and a Poly-silicon layer can be deposited, and after boron or phosphorus doping, an NPoly layer of a doped polysilicon layer is formed. As Figure 4 As shown, by using the passivation method of the present invention, a tunneling oxide layer structure with a loose middle and dense sides can be grown in the N region and P region of the TBC cell structure, and a Poly-silicon layer can be deposited, and after boron or phosphorus doping, an NPoly layer and a PPoly layer of a doped polysilicon layer are formed.

[0055] For structures such as BC cells that require further processing of the boron-doped Poly layer structure, the tunneling oxide layer grown by the present invention can better resist the influence of laser on the boron-doped Poly layer. Figure 5 The concentration-depth curves of two BSG film removal methods, laser film removal and cleaning film removal, are shown. It can be seen from them that the laser process has no obvious influence on the subsequent inward diffusion of boron atoms. At the same time, its uniform tunneling oxide film layer is more likely to form a flatter surface during the subsequent wet etching process. For the BC structure battery prepared by using the passivation method of the present invention, from Figure 6 The backside scanning electron microscope image shows that by using the passivation method of the present invention, a P region, an N region, and a Gap region with better flatness can be formed.

[0056] Hereinafter, the specific embodiments of the present invention will be further explained and illustrated through examples and comparative examples.

[0057] The reagents, materials, and instruments used in the following description are all conventional reagents, conventional materials, and conventional instruments, which can be obtained commercially, unless otherwise specified. The methods in the examples are all conventional methods in the art, unless otherwise specified.

[0058] Example 1

[0059] The passivation method of the boron-doped Poly layer provided by the present invention includes the following steps.

[0060] S1. Prepare an N-type silicon wafer 1 with a resistivity of 10 Ω·cm and a thickness of 180 μm, polish both sides, clean it, put it into an LPCVD device, evacuate to a near-vacuum state, slowly heat the furnace tube to 570 °C, slowly introduce oxygen into the furnace tube at a flow rate of 10 L / min, and keep the pressure in the furnace tube below 0.5 standard atmospheric pressure during the heating process. Oxidize the silicon wafer for the first time for 15 minutes in a low-temperature and low-pressure environment, and grow a dense first oxide layer 2 with a thickness of 0.4 nm on the silicon wafer surface.

[0061] S2. Continuously introduce oxygen. The pressure inside the furnace tube is 1 standard atmospheric pressure. Raise the temperature inside the furnace tube to 630 °C. Perform the second oxidation of the silicon wafer for 12 minutes in an environment of high temperature and normal pressure, and continuously grow a relatively loose second oxide layer 3 with a thickness of 0.8 nm on the surface of the silicon wafer.

[0062] S3. Stop introducing oxygen, keep the pressure inside the furnace tube unchanged, lower the temperature to 580 °C, perform the third oxidation of the silicon wafer for 12 minutes in an environment of low temperature and normal pressure, and continuously grow a relatively dense third oxide layer 4 with a thickness of 0.2 nm on the surface of the silicon wafer. Thus, a tunneling oxide layer structure with a loose middle and dense sides is grown on the surface of the silicon wafer.

[0063] S4. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 600 °C, evacuate the air and then introduce silane. The vacuum pressure is 200 mTorr. Deposit a Poly silicon layer on the first oxide layer 2 in an environment of high temperature and low pressure until the film thickness meets the process requirements.

[0064] S5. Use a high-temperature diffusion tube to deposit and oxidize boron atoms, introduce boron trichloride and oxygen. First deposit at 830 °C for 1000 seconds, then raise the temperature to 960 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly silicon layer to form a doped polycrystalline silicon layer 5.

[0065] Examples 2 - 4

[0066] Examples 2 - 4 include most of the operation steps in Example 1. The differences lie in the temperature, pressure, time, oxide layer thickness, and doped atoms of the three oxidations. Specifically as follows.

[0067] Example 2

[0068] The passivation method of the boron-doped Poly layer provided by the present invention includes the following steps.

[0069] S1. Prepare an N-type silicon wafer with a resistivity of 1 Ω·cm and a thickness of 130 μm, polish both sides, clean it, put it into the LPCVD equipment, evacuate to a near-vacuum state, slowly raise the temperature of the furnace tube to 500 °C, slowly introduce oxygen into the furnace tube at a flow rate of 5 L / min, and keep the pressure inside the furnace tube below 0.3 standard atmospheric pressure during the temperature-raising process. Perform the first oxidation of the silicon wafer for 10 minutes in an environment of low temperature and low pressure, and grow a dense first oxide layer with a thickness of 0.3 nm on the surface of the silicon wafer.

[0070] S2. Continuously introduce oxygen. The pressure inside the furnace tube is 1 standard atmospheric pressure. Raise the temperature inside the furnace tube to 610 °C. Perform the second oxidation of the silicon wafer for 10 minutes in an environment of high temperature and normal pressure, and continuously grow a relatively loose second oxide layer with a thickness of 0.5 nm on the surface of the silicon wafer.

[0071] S3. Continuously introduce oxygen, keep the pressure inside the furnace tube unchanged, reduce the temperature to 550 °C, and perform the third oxidation of the silicon wafer for 10 minutes in an environment of low temperature and normal pressure. A relatively dense third oxide layer with a thickness of 0.2 nm continues to grow on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a loose middle and dense sides is grown on the surface of the silicon wafer.

[0072] S4. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 550 °C, introduce silane, and at the same time evacuate the air. The vacuum pressure is 180 mTorr. In an environment of high temperature and low pressure, deposit a Poly-silicon layer on the first oxide layer until the film thickness required by the process is reached.

[0073] S5. Use a high-temperature diffusion tube to deposit and oxidize and promote boron atoms. Introduce boron trichloride and oxygen. First deposit at 810 °C for 1200 seconds, then raise the temperature to 990 °C, and continue to introduce more oxygen to promote for 30 minutes to dope a certain concentration of boron in the Poly-silicon layer to form a doped polycrystalline silicon layer.

[0074] Example 3

[0075] The passivation method of the phosphorus-doped Poly layer provided by the present invention includes the following steps.

[0076] S1. Prepare an N-type silicon wafer with a resistivity of 20 Ω·cm and a thickness of 220 μm, polish both sides, clean it, put it into the LPCVD equipment, evacuate to a near-vacuum state, slowly raise the temperature of the furnace tube to 580 °C, and slowly introduce oxygen into the furnace tube at a flow rate of 20 L / min to keep the pressure inside the furnace tube below 0.5 standard atmospheric pressure during the heating process. Perform the first oxidation of the silicon wafer for 20 minutes in an environment of low temperature and low pressure, and grow a dense first oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer.

[0077] S2. Continuously introduce oxygen, the pressure inside the furnace tube is 1 standard atmospheric pressure, raise the temperature inside the furnace tube to 640 °C, and perform the second oxidation of the silicon wafer for 20 minutes in an environment of high temperature and normal pressure. A relatively loose second oxide layer with a thickness of 1 nm continues to grow on the surface of the silicon wafer.

[0078] S3. Continuously introduce oxygen, keep the pressure inside the furnace tube unchanged, reduce the temperature to 590 °C, and perform the third oxidation of the silicon wafer for 20 minutes in an environment of low temperature and normal pressure. A relatively dense third oxide layer with a thickness of 0.4 nm continues to grow on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a loose middle and dense sides is grown on the surface of the silicon wafer.

[0079] S4. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 640 °C, evacuate the air and then introduce silane. The vacuum pressure is 300 mTorr. In a high-temperature and low-pressure environment, deposit a Poly-silicon layer on the first oxide layer until the film thickness meets the process requirements.

[0080] S5. Use a high-temperature diffusion tube to deposit and oxidize phosphorus atoms. Introduce phosphorus oxychloride and oxygen. First, deposit at 850 °C for 600 seconds, then raise the temperature to 920 °C, and continue to introduce more oxygen to promote for 10 minutes to dope a certain concentration of phosphorus in the Poly-silicon layer to form a doped polycrystalline silicon layer.

[0081] Example 4

[0082] The passivation method of the phosphorus-doped Poly layer provided by the present invention includes the following steps.

[0083] S1. Prepare an N-type silicon wafer with a resistivity of 12 Ω·cm and a thickness of 200 μm. Polish both sides, clean it, put it into the LPCVD equipment, evacuate to a near-vacuum state, slowly raise the temperature of the furnace tube to 580 °C, and slowly introduce oxygen into the furnace tube at a flow rate of 30 L / min to keep the pressure inside the furnace tube below 0.3 standard atmospheric pressure during the temperature-raising process. Oxidize the silicon wafer for the first time for 13 minutes in a low-temperature and low-pressure environment to grow a dense first oxide layer with a thickness of 0.5 nm on the surface of the silicon wafer.

[0084] S2. Continuously introduce oxygen, keep the pressure inside the furnace tube at 1 standard atmospheric pressure, raise the temperature inside the furnace tube to 620 °C, oxidize the silicon wafer for the second time for 15 minutes in a high-temperature and normal-pressure environment to continue growing a relatively loose second oxide layer with a thickness of 0.9 nm on the surface of the silicon wafer.

[0085] S3. Stop introducing oxygen, keep the pressure inside the furnace tube unchanged, lower the temperature to 570 °C, oxidize the silicon wafer for the third time for 14 minutes in a low-temperature and normal-pressure environment to continue growing a relatively dense third oxide layer with a thickness of 0.25 nm on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a loose middle and dense sides is grown on the surface of the silicon wafer.

[0086] S4. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 620 °C, evacuate the air and then introduce silane. The vacuum pressure is 240 mTorr. In a high-temperature and low-pressure environment, deposit a Poly-silicon layer on the first oxide layer until the film thickness meets the process requirements.

[0087] S5. Use a high-temperature diffusion tube to deposit and oxidize phosphorus atoms. Introduce phosphorus oxychloride and oxygen. First, deposit at 800 °C for 1500 seconds, then raise the temperature to 880 °C, and continue to introduce more oxygen to promote for 20 minutes to dope a certain concentration of phosphorus in the Poly-silicon layer to form a doped polycrystalline silicon layer.

[0088] Comparative Example 1

[0089] The difference between Comparative Example 1 and Examples 1 and 2 is that an existing direct high-temperature grown tunneling oxide layer is used, which is as follows.

[0090] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm, polish both sides, clean it, put it into an LPCVD device, evacuate, wait for the furnace tube to slowly heat up to 620 °C, then introduce oxygen with a flow rate of 36 L / min, return the furnace tube to atmospheric pressure, and at the same time oxidize the silicon wafer to grow a 2-nm-thick tunneling oxide layer on the surface of the silicon wafer.

[0091] S2. Continue to use the LPCVD device, control the temperature in the furnace tube at 600 °C, evacuate and then introduce silane, with a vacuum pressure of 200 mTorr, to deposit a Poly silicon layer on the tunneling oxide layer.

[0092] S3. Use a high-temperature diffusion tube for the deposition and oxidation promotion of boron atoms, introduce boron trichloride and oxygen, first deposit at 830 °C for 1000 seconds, then raise the temperature to 960 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly silicon layer to form a doped polysilicon layer.

[0093] Comparative Example 2

[0094] The difference between Comparative Example 2 and Examples 3 and 4 is that an existing direct high-temperature grown tunneling oxide layer is used, which is as follows.

[0095] S1. Prepare an N-type silicon wafer with a resistivity of 20 Ω·cm and a thickness of 220 μm, polish both sides, clean it, put it into an LPCVD device, evacuate, wait for the furnace tube to heat up to 610 °C, then introduce oxygen with a flow rate of 36 L / min, return the furnace tube to atmospheric pressure, and at the same time oxidize the silicon wafer to grow a 1.6-nm tunneling oxide layer on the surface of the silicon wafer.

[0096] S2. Continue to use the LPCVD device, control the temperature in the furnace tube at 615 °C, evacuate and then introduce silane, with a vacuum pressure of 300 mTorr, to deposit a Poly silicon layer on the tunneling oxide layer in a high-temperature and low-pressure environment until the film thickness required by the process is reached.

[0097] S3. Use a high-temperature diffusion tube for the deposition and oxidation promotion of phosphorus atoms, introduce phosphorus oxychloride and oxygen, first deposit at 850 °C for 600 seconds, then raise the temperature to 920 °C, and continue to introduce more oxygen to promote for 10 minutes to dope a certain concentration of phosphorus in the Poly silicon layer to form a doped polysilicon layer.

[0098] Comparative Example 3

[0099] The difference between Comparative Example 3 and Examples 1 and 2 lies in that a tunneling oxide layer with a two-layer structure is grown by low-temperature and low-pressure oxidation and high-temperature and normal-pressure oxidation, as follows.

[0100] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm. Double-side polish and clean it thoroughly. Place it in an LPCVD device, evacuate the air, and wait for the furnace tube to heat up to 570 °C. Then, introduce oxygen with a flow rate of 10 L / min, and keep the pressure in the furnace tube below 0.5 standard atmospheric pressure during the heating process. Oxidize the silicon wafer for 15 minutes in a low-temperature and low-pressure environment to grow a dense oxide layer with a thickness of 0.4 nm on the surface of the silicon wafer.

[0101] S2. Continuously introduce oxygen, keep the pressure in the furnace tube at 1 standard atmospheric pressure, and raise the temperature in the furnace tube to 630 °C. Oxidize the silicon wafer for 12 minutes in a high-temperature and normal-pressure environment to continue growing a relatively porous oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer. Thus, a tunneling oxide layer structure with a loose inner side and a dense outer side is grown on the surface of the silicon wafer.

[0102] S3. Continue to use the LPCVD device, control the temperature in the furnace tube at 600 °C, evacuate the air, and then introduce silane. The vacuum pressure is 200 mTorr. Deposit a Poly silicon layer on the first oxide layer 2 in a high-temperature and low-pressure environment.

[0103] S4. Use a high-temperature diffusion tube for the deposition and oxidation promotion of boron atoms. Introduce boron trichloride and oxygen. First, deposit at 830 °C for 1000 seconds, then raise the temperature to 960 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly silicon layer to form a doped polycrystalline silicon layer.

[0104] Comparative Example 4

[0105] The difference between Comparative Example 4 and Examples 1 and 2 lies in that a tunneling oxide layer with a two-layer structure is grown by combining high-temperature and normal-pressure oxidation and low-temperature and normal-pressure oxidation, as follows.

[0106] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm. Double-side polish and clean it thoroughly. Place it in an LPCVD device, evacuate the air, and wait for the furnace tube to heat up to 630 °C. Then, introduce oxygen with a flow rate of 10 L / min to normal pressure, and oxidize the silicon wafer for 12 minutes in a high-temperature and normal-pressure environment to continue growing a relatively porous oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer.

[0107] S2. Continue to introduce oxygen, keep the pressure inside the furnace tube unchanged, lower the temperature to 580 °C, and oxidize the silicon wafer for 12 minutes in an environment of low temperature and normal pressure, and continue to grow a relatively dense oxide layer with a thickness of 0.2 nm on the surface of the silicon wafer; thus, a tunneling oxide layer structure with a dense inner side and a loose outer side is grown on the surface of the silicon wafer.

[0108] S3. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 600 °C, evacuate the air and then introduce silane, with a vacuum pressure of 200 mTorr, and deposit a Poly silicon layer on the first oxide layer 2 in an environment of high temperature and low pressure.

[0109] S4. Use a high-temperature diffusion tube to deposit and oxidize boron atoms, introduce boron trichloride and oxygen, first deposit at 830 °C for 1000 seconds, then raise the temperature to 960 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly silicon layer to form a doped polysilicon layer.

[0110] Comparative Example 5

[0111] The difference between Comparative Example 5 and Examples 1 and 2 is that a tunneling oxide layer with a two-layer structure is grown by combining low-temperature and low-pressure oxidation with low-temperature and normal-pressure oxidation, and the temperatures for deposition and oxidation promotion are different, as follows.

[0112] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm, polish both sides, clean it, put it into the LPCVD equipment, evacuate the air, and after waiting for the furnace tube to heat up to 570 °C, introduce oxygen with a flow rate of 10 L / min to keep the pressure inside the furnace tube below 0.2 standard atmospheric pressure during the heating process, and oxidize the silicon wafer for 15 minutes in an environment of low temperature and low pressure, and grow a dense oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer.

[0113] S2. Continue to introduce oxygen, with the pressure inside the furnace tube being 1 standard atmospheric pressure and the temperature inside the furnace tube being 580 °C, oxidize the silicon wafer for 12 minutes in an environment of low temperature and normal pressure, and continue to grow a relatively dense oxide layer with a thickness of 0.4 nm on the surface of the silicon wafer; thus, a two-layer dense tunneling oxide layer structure is grown on the surface of the silicon wafer.

[0114] S3. Continue to use the LPCVD equipment, control the temperature inside the furnace tube at 600 °C, evacuate the air and then introduce silane, with a vacuum pressure of 200 mTorr, and deposit a Poly silicon layer on the first oxide layer 2 in an environment of high temperature and low pressure.

[0115] S4. Use a high-temperature diffusion tube to deposit and oxidize boron atoms, introduce boron trichloride and oxygen, first deposit at 830 °C for 1000 seconds, then raise the temperature to 950 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly silicon layer to form a doped polysilicon layer.

[0116] Comparative Example 6

[0117] The difference between Comparative Example 6 and Examples 1 and 2 is that a tunneling oxide layer with a two-layer structure is grown by combining low-temperature low-pressure oxidation and low-temperature atmospheric-pressure oxidation, as follows.

[0118] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm. Double-side polish and clean it, then put it into an LPCVD device. After evacuating, wait for the furnace tube to heat up to 570 °C, and then introduce oxygen with a flow rate of 10 L / min, keeping the pressure in the furnace tube below 0.2 standard atmospheric pressure during the heating process. Oxidize the silicon wafer in a low-temperature low-pressure environment for 15 minutes to grow a dense oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer.

[0119] S2. Continue to introduce oxygen. The pressure in the furnace tube is 1 standard atmospheric pressure, and the temperature in the furnace tube is 580 °C. Oxidize the silicon wafer in a low-temperature atmospheric-pressure environment for 12 minutes to continue growing a relatively dense oxide layer with a thickness of 0.4 nm on the surface of the silicon wafer. Thus, a two-layer dense tunneling oxide layer structure is grown on the surface of the silicon wafer.

[0120] S3. Continue to use the LPCVD device, control the temperature in the furnace tube at 600 °C, evacuate and then introduce silane. The vacuum pressure is 200 mTorr. Deposit a Poly-silicon layer on the first oxide layer 2 in a high-temperature low-pressure environment.

[0121] S4. Use a high-temperature diffusion tube for the deposition and oxidation promotion of boron atoms. Introduce boron trichloride and oxygen. First deposit at 830 °C for 1000 seconds, then raise the temperature to 960 °C and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly-silicon layer to form a doped polycrystalline silicon layer.

[0122] Comparative Example 7

[0123] The difference between Comparative Example 7 and Examples 1 and 2 is that a tunneling oxide layer with a two-layer structure is grown by combining low-temperature low-pressure oxidation and low-temperature atmospheric-pressure oxidation, and the temperatures for deposition and oxidation promotion are different, as follows.

[0124] S1. Prepare an N-type silicon wafer with a resistivity of 10 Ω·cm and a thickness of 180 μm. Double-side polish and clean it, then put it into an LPCVD device. After evacuating, wait for the furnace tube to heat up to 570 °C, and then introduce oxygen with a flow rate of 10 L / min, keeping the pressure in the furnace tube below 0.2 standard atmospheric pressure during the heating process. Oxidize the silicon wafer in a low-temperature low-pressure environment for 15 minutes to grow a dense oxide layer with a thickness of 0.8 nm on the surface of the silicon wafer.

[0125] S2. Continue to introduce oxygen. The pressure inside the furnace tube is 1 standard atmosphere, and the temperature inside the furnace tube is 580 °C. Oxidize the silicon wafer for 12 minutes in a low-temperature and normal-pressure environment, and continue to grow a relatively dense oxide layer with a thickness of 0.4 nm on the surface of the silicon wafer. Thus, two dense tunneling oxide layer structures are grown on the surface of the silicon wafer.

[0126] S3. Continue to use the LPCVD equipment to control the temperature inside the furnace tube at 600 °C. After evacuating, introduce silane. The vacuum pressure is 200 mTorr. Deposit a Poly-silicon layer on the first oxide layer 2 in a high-temperature and low-pressure environment.

[0127] S4. Use a high-temperature diffusion tube for the deposition and oxidation promotion of boron atoms. Introduce boron trichloride and oxygen. First, deposit at 830 °C for 1000 seconds, then raise the temperature to 970 °C, and continue to introduce more oxygen to promote for 22 minutes to dope a certain concentration of boron in the Poly-silicon layer to form a doped polycrystalline silicon layer.

[0128] Performance Test

[0129] Perform performance tests on the silicon wafers with a passivation contact structure obtained by using the above examples and comparative examples. All the data in Table 1 are directly tested on the symmetric structure obtained after growing Poly layers on both sides and boron diffusion on both sides of N-type silicon wafers.

[0130] Use the WCT-120 instrument of the American Sinton company to measure the minority carrier lifetime (Lifetime), the recombination current density (J0), the implied open-circuit voltage (iVoc), and the implied fill factor (iFF). Use the PL-R3 instrument to test the photoluminescence brightness, where the excitation brightness is 1 times the standard brightness of sunlight (1 Sun). The test results are shown in Table 1.

[0131] Table 1

[0132]

[0133] It can be seen from the test results of Examples 1, 2 and Comparative Example 1 that the passivation method of the present invention has significantly improved the minority carrier lifetime, iVoc, iFF and PL brightness compared with the boron-doped Poly layer prepared by the prior art, and the recombination current density J0 has been significantly reduced, showing a better passivation effect.

[0134] It can be seen from the test results of Examples 3, 4 and Comparative Example 2 that although phosphorus Poly itself has good passivation performance, the passivation effect is still improved to a certain extent by the passivation method of the present invention compared with the phosphorus-doped Poly layer prepared by the prior art. The minority carrier lifetime and PL brightness have been significantly improved, iVoc and iFF have been improved, and the recombination current density J0 has been reduced.

[0135] As can be seen from the test results of Examples 1 and 2 and Comparative Examples 3 to 7, by superimposing three layers of oxide layers with different compactness in the present invention, compared with the two-layer structure, the passivation effect of the boron- and phosphorus-doped Poly layer structure can be greatly improved; the minority carrier lifetime, iVoc, iFF, and PL brightness are all significantly improved, and the recombination current density J0 is significantly reduced, showing a good passivation effect. Moreover, the tunneling oxide layer grown in the present invention is less affected by the temperature fluctuation of the subsequent boron diffusion, and can accept a fluctuation of 30 °C above the optimal oxidation push temperature.

[0136] As can be seen from the test results of Examples 1 and 2 and Comparative Examples 5 to 7, when the tunneling oxide layer is passivated under different oxidation push temperatures of boron diffusion, if a low-temperature method (Comparative Examples 5 to 7) is used throughout to grow a dense tunneling oxide layer, at the optimal oxidation push temperature of boron diffusion (Comparative Example 6), a good passivation effect can usually be achieved. However, it is very sensitive to the change of the oxidation push temperature. When the temperature fluctuates up and down by about 10 °C (Comparative Examples 5 and 7), its passivation effect decreases significantly, which is not conducive to large-scale industrial production.

[0137] The present invention has been further described above with reference to specific embodiments. However, it should be understood that the specific description herein should not be construed as a limitation on the essence and scope of the present invention. Various modifications made by those of ordinary skill in the art to the above embodiments after reading this specification all fall within the scope protected by the present invention.

Claims

1. A passivation method for boron- and phosphorus-doped Poly layer, characterized in that, It includes the following steps: S1. Provide a clean and polished silicon wafer. Use an LPCVD device to evacuate the air and introduce oxygen. At a low temperature and low pressure below 600 °C, perform the first oxidation on the silicon wafer to grow a first oxide layer with a thickness of 0.3 - 0.8 nm and being dense on the surface of the silicon wafer; S2. Raise the temperature in step S1 by 50 - 220 °C, continuously introduce oxygen, and at a pressure greater than or equal to 1 standard atmosphere, perform the second oxidation on the silicon wafer to continuously grow a second oxide layer with a thickness of 0.5 - 1 nm and being porous on the surface of the silicon wafer; S3. Stop introducing oxygen, keep the pressure unchanged, lower the temperature to below 600 °C, and perform the third oxidation on the silicon wafer to continuously grow a third oxide layer with a thickness of 0.1 - 0.4 nm and being dense on the surface of the silicon wafer; S4. Continue to use the LPCVD device. Raise the temperature in step S3 by 0 - 50 °C, evacuate the air and then introduce silane. At a high temperature and low pressure, deposit a Poly - silicon layer on the first oxide layer until the film thickness meets the process requirements; S5. Use a high - temperature diffusion tube to deposit and oxidize - drive boron atoms or phosphorus atoms, so that a certain concentration of boron or phosphorus is doped in the Poly - silicon layer to form a doped poly - silicon layer.

2. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, characterized in that, In step S1, the temperature is 400 - 590 °C, the pressure is 0.1 - 0.5 standard atmosphere, and the first oxidation time is 10 - 20 minutes.

3. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, characterized in that, In step S2, the temperature is 610 - 640 °C, the pressure is normal pressure, and the second oxidation time is 10 - 20 minutes.

4. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, wherein In step S3, the temperature is 550 - 590 °C, the pressure is normal pressure, and the third oxidation time is 10 - 20 minutes.

5. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, characterized in that, In step S4, the temperature is 550 - 640 °C, and the vacuum pressure is 180 - 300 mTorr.

6. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, wherein In steps S1 and S2, the flow rate of the introduced oxygen is 5 - 30 L / min.

7. The passivation method of the boron- and phosphorus-doped Poly layer according to claim 1, characterized in that, In step S5, during the process of depositing and oxidizing - driving boron atoms, the deposition temperature is 800 - 850 °C, and the temperature for oxidation - driving is 940 - 1000 °C; during the process of depositing and oxidizing - driving phosphorus atoms, the deposition temperature is 800 - 850 °C, and the temperature for oxidation - driving is 880 - 920 °C.

8. A passivated contact structure of a boron- and phosphorus-doped Poly layer, characterized in that, The passivated contact structure includes a first oxide layer, a second oxide layer, a third oxide layer, and a doped poly - silicon layer grown on a silicon wafer by the passivation method of the boron - and phosphorus - doped Poly layer as described in any one of claims 1 - 7. The doped poly - silicon layer is above the first oxide layer. The first oxide layer, the second oxide layer, and the third oxide layer form a tunneling oxide layer. The second oxide layer is in the middle of the tunneling oxide layer, being thick and porous; the first oxide layer and the third oxide layer are on both sides of the tunneling oxide layer, being thin and dense.

9. A battery with a passivated contact structure having a boron and phosphorus doped Poly layer, characterized in that, The battery includes a silicon wafer and a passivated contact structure as described in claim 8 formed on the surface of the silicon wafer.

10. The battery with a passivated contact structure having a boron- and phosphorus-doped Poly layer according to claim 9, characterized in that, The battery is a TOPCon battery, a TBC battery, or a perovskite tandem battery.

Images