Passivated contact structure and preparation method therefor, and solar cell

Abstract

A passivated contact structure and a preparation method therefor, and a solar cell. The passivated contact structure comprises a tunneling layer (2) and a polycide layer (31), the polycide layer (31) being a polycrystalline silicon oxide layer and / or a polycrystalline silicon carbide layer, wherein the polycide layer (31) is of an n type or a p type, a doping element is doped into the polycide layer (31) at a mass concentration ranging from 1.49×1020 to 3×1020.

Description

Passivation contact structure and preparation method thereof, and solar cell

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on October 11, 2023, with application number 202311316885.1 and public name “Passivated contact structure and preparation method thereof, solar cell”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present disclosure relates to the technical field of solar cells, and in particular to a passivation contact structure and a preparation method thereof, and a solar cell. Background Art

[0003] Currently, the passivation contact structure of solar cells is generally a tunneling layer superimposed on a polysilicon layer (poly-Si). However, the polysilicon layer itself has severe parasitic light absorption, which easily reduces the short-circuit current of the passivation contact cell.

[0004] In order to reduce parasitic absorption and increase short-circuit current, people use polycrystalline silicon oxide layer (poly-SiO x ) or polycrystalline silicon carbide layer (poly-SiC x ) to replace the original polysilicon layer. However, the sheet resistance of the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer is significantly higher than that of the polysilicon layer, which easily leads to an increase in series resistance, a reduction in the fill factor of the battery, and a reduction in the conversion efficiency of the battery.

[0005] Summary of the Invention

[0006] In a first aspect, the present disclosure provides a passivation contact structure comprising a tunneling layer and a polysilicide layer, wherein the polysilicide layer is a polycrystalline silicon oxide layer and / or a polycrystalline silicon carbide layer;

[0007] The polysilicide layer is of n-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 to 3×10 20 between; or,

[0008] The polysilicide layer is of p-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 to 3×10 20 between.

[0009] In some embodiments of the present disclosure, the polycide layer is a polycide layer that is plasma-treated after deposition.

[0010] In some embodiments of the present disclosure, the polysilicide layer is of n-type, and the gas used in the plasma treatment is a gas containing phosphorus; or

[0011] The polysilicide layer is of p-type, and the gas used in the plasma treatment is a boron-containing gas.

[0012] In some embodiments of the present disclosure, the thickness of the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer is 5 nm to 150 nm.

[0013] In some embodiments of the present disclosure, the passivation contact structure further includes at least one of a lightly doped polysilicon layer, an undoped intrinsic polysilicon layer, and a heavily doped polysilicon layer; wherein,

[0014] The lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is located on a side of the polysilicide layer close to the tunneling layer; the heavily doped polysilicon layer is located on a side of the polysilicide layer away from the tunneling layer.

[0015] In some embodiments of the present disclosure, the thickness of the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is ≤80 nm, and the thickness of the heavily doped polysilicon layer is ≤40 nm.

[0016] In some embodiments of the present disclosure, the passivation contact structure includes the lightly doped polysilicon layer, and the thickness of the lightly doped polysilicon layer is 5 nm to 80 nm.

[0017] In some embodiments of the present disclosure, the passivation contact structure includes the undoped intrinsic polysilicon layer, and the thickness of the undoped intrinsic polysilicon is 2 nm to 40 nm.

[0018] In some embodiments of the present disclosure, the heavily doped polysilicon layer has a thickness of 5 nm to 100 nm.

[0019] In a second aspect, the present disclosure provides a method for preparing a passivation contact structure, the method comprising the following steps:

[0020] The polysilicide layer is deposited on the tunneling layer, wherein the polysilicide layer is a polycrystalline silicon oxide layer or a polycrystalline silicon carbide layer, and the deposited polysilicide layer is subjected to plasma treatment; wherein,

[0021] The polysilicide layer is of n-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 to 3×10 20 between; or,

[0022] The polysilicide layer is of p-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 to 3×10 20 between.

[0023] In some embodiments of the present disclosure, the plasma treatment has a pressure of 0.5 mBar to 4 mBar, a power of 2000 W to 20000 W, a temperature of 350° C. to 500° C., and a time of 10 s to 200 s.

[0024] In some embodiments of the present disclosure, the polycide layer is of n-type, and the reaction gas of the plasma treatment includes PH3 and H2; or,

[0025] The polysilicide layer is of p-type, and the reaction gas for the plasma treatment includes B2H6 and H2.

[0026] In some embodiments of the present disclosure, the ratio of the gas flow rates of the PH3 and the H2 is (100-2000):(3000-30000), and the ratio of the gas flow rates of the B2H6 and the H2 is (100-2000):(3000-30000).

[0027] In some embodiments of the present disclosure, the polycrystalline silicide layer is of n-type, the reaction gas for preparing the polycrystalline silicon oxide layer is an oxygen-containing gas, SiH4, PH3 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the reaction gas for preparing the polycrystalline silicon carbide layer is CH4, SiH4, PH3 and H2; or,

[0028] The polycrystalline silicide layer is p-type, and the reaction gas for preparing the polycrystalline silicon oxide is oxygen-containing gas, SiH4, B2H6 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the reaction gas for preparing the polycrystalline silicon carbide is CH4, SiH4, B2H6 and H2.

[0029] In some embodiments of the present disclosure, the polycrystalline silicide layer is of n-type, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon oxide layer is: oxygen-containing gas: SiH4 = (0.02-1.5): 1, PH3: SiH4 = (0.05%-5%): 1, H2: SiH4 = (0.5-50): 1, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon carbide layer is: CH4: SiH4 = (0.05-4): 1, PH3: SiH4 = (0.05%-5%): 1, H2: SiH4 = (0.5-50): 1; or,

[0030] The polycrystalline silicide layer is p-type, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon oxide layer is: oxygen-containing gas: SiH4 = (0.02~1.5):1, B2H6:SiH4 = (0.05%~5%):1, H2:SiH4 = (0.5~50):1, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon carbide layer is: CH4:SiH4 = (0.05~4):1, B2H6:SiH4 = (0.05%~5%):1, H2:SiH4 = (0.5~50):1.

[0031] In some embodiments of the present disclosure, before preparing the polycide layer, the method further includes: preparing a lightly doped polysilicon layer or an undoped intrinsic polysilicon layer on the tunneling layer; and / or;

[0032] After the polycrystal silicide layer is prepared, the method further includes: preparing a heavily doped polysilicon layer on the polycrystal silicide layer.

[0033] In some embodiments of the present disclosure, the thickness of the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is ≤80 nm, and the thickness of the heavily doped polysilicon layer is ≤40 nm.

[0034] In some embodiments of the present disclosure, the polycide layer is n-type, the heavily doped polysilicon layer or the lightly doped polysilicon layer is n-type, the reaction gas for preparing the heavily doped polysilicon layer is SiH4, PH3 and H2, and the reaction gas for preparing the lightly doped intrinsic polycide layer is SiH4, PH3 and H2;

[0035] The polysilicon layer is p-type, the heavily doped polysilicon layer or the lightly doped polysilicon layer is p-type, the reaction gases for preparing the p-type heavily doped polysilicon layer are SiH4, B2H6 and H2, and the reaction gases for preparing the p-type lightly doped intrinsic polysilicon layer are SiH4, B2H6 and H2.

[0036] In some embodiments of the present disclosure, the ratio of the flow rate of the reaction gas for preparing the n-type heavily doped polysilicon layer is: PH3:SiH4=(0.1%-10%):1; H2:SiH4=(0.5-100):1;

[0037] The gas flow ratio of the reaction gas for preparing the n-type lightly doped intrinsic polysilicide layer is PH3:SiH4=(0.05%-2%):1; H2:SiH4=(0.5-100):1;

[0038] The gas flow ratio of the reaction gas for preparing the p-type heavily doped polysilicon layer is: B2H6:SiH4=(0.1%-10%):1; H2:SiH4=(0.5-100):1;

[0039] The gas flow ratio of the reaction gas for preparing the p-type lightly doped intrinsic polysilicide layer is: B2H6:SiH4=(0.05%~2%):1; H2:SiH4=(0.5~100):1.

[0040] In some embodiments of the present disclosure, the reaction gases for preparing the undoped intrinsic polysilicon are SiH4 and H2, and the gas flow ratio of the reaction gases for preparing the undoped intrinsic polysilicon is H2:SiH4=(0.5~100):1.

[0041] In a third aspect, the present disclosure also provides a solar cell, which includes a silicon wafer and a passivation contact structure arranged on the front and / or back side of the silicon wafer, wherein the passivation contact structure is the passivation contact structure according to any one of claims 1 to 9, or the passivation contact structure prepared by the preparation method according to any one of claims 7 to 13.

[0042] In some embodiments of the present disclosure, the silicon wafer is any one of an n-type single crystal silicon wafer, an n-type multi-crystalline silicon wafer, a p-type single crystal silicon wafer, and a p-type multi-crystalline silicon wafer. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0044] FIG1 is a schematic diagram of a partial structure of a passivation contact battery disclosed in Example 1 of the present invention;

[0045] FIG2 is a schematic diagram of a partial structure of a passivation contact battery disclosed in Example 5 of the present invention;

[0046] FIG3 is a schematic diagram of a partial structure of a passivation contact battery disclosed in Example 6 of the present invention;

[0047] FIG4 is a comparison diagram of Raman curves of the polysilicide layer in Example 1 of the present invention and Comparative Example 4.

[0048] Icons: 1. Silicon wafer; 2. Tunneling layer; 31. Polysilicon layer; 32. Heavily doped polysilicon layer; 33. Undoped intrinsic polysilicon layer; 4. Passivation film layer; 5. Metal electrode. DETAILED DESCRIPTION

[0049] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0050] In a first aspect, embodiments of the present application provide a passivation contact structure.

[0051] 2 , the passivation contact structure includes a tunneling layer 2 and a polysilicide layer 31. The polysilicide layer 31 is n-type or p-type. When the polysilicide layer 31 is n-type, the doping mass concentration of the doping element in the polysilicide layer 31 is 1.49×10 20 to 3×10 20 When the polysilicide layer 31 is p-type, the doping mass concentration of the doping element in the polysilicide layer 31 is between 1.49×10 20 to 3×10 20 The polycide layer 31 is a polycrystalline silicon oxide layer and / or a polycrystalline silicon carbide layer.

[0052] The doping mass concentration of the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer is increased to 1.05×10 20 to 1.95×10 20 In the meantime, the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer at this doping mass concentration is beneficial to improving the fill factor of the battery, thereby overcoming the defect that the fill factor of the battery decreases after the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer is used, and improving the electrical performance of the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer.

[0053] For example, when the doping element in the polysilicide layer 31 is phosphorus, the doping mass concentration of phosphorus can be 1.49×10 20 , 1.6×10 20 , 1.7×10 20 , 1.75×10 20 , 1.8×10 20 , 1.85×10 20 , 1.9×10 20 , 2×10 20 , 2.1×10 20 , 2.2×10 20 , 2.4×10 20 , 2.6×10 20 , 2.7×10 20 , 2.8×10 20 , 2.9×10 20 , 3.0×10 20When the doping element in the polysilicide layer 31 is boron, the doping mass concentration of boron in the polysilicide layer can be 1.49×10 20 , 1.6×10 20 , 1.7×10 20 , 1.75×10 20 , 1.8×10 20 , 1.85×10 20 , 1.9×10 20 , 2×10 20 , 2.1×10 20 , 2.2×10 20 , 2.4×10 20 , 2.6×10 20 , 2.7×10 20 , 2.8×10 20 , 2.9×10 20 , 3.0×10 20 wait.

[0054] It should be noted that the embodiment of the present application does not limit the tunneling layer 2, as long as it can achieve the tunneling passivation contact function.

[0055] In some embodiments, the polycide layer 31 is a polycide layer 31 that is plasma-treated after deposition.

[0056] Increasing the dopant concentration of the polycide layer 31 helps reduce the sheet resistance of the polycide layer 31 and improve the fill factor of the battery. Increasing the concentration of the dopant-containing gas during the deposition of the polycide layer 31 can increase the concentration of the dopant element in the polycide layer 31, but it can also reduce the film quality of the polycide layer 31, resulting in a decrease in battery efficiency.

[0057] Taking the n-type polycide layer 31 as an example, currently, plasma enhanced chemical vapor deposition (PECVD) is generally used to deposit the n-type polycide layer 31. In order to increase the phosphorus doping mass concentration of the n-type polycide layer 31, it is necessary to increase the concentration of the phosphorus-containing doping gas during the deposition of the n-type polycide layer 31.

[0058] Taking PH3 as an example of a phosphorus-containing doping gas, PH3 is a primary product of PH. PH first enters the interface structure of Si grains and bonds with Si to form Si-PH. Since the bond energy of PH is slightly greater than the Si-H bond, the PH bond after bonding with Si is also easily broken. P atoms enter the interior of the Si grains and form P-Si bonds with Si, achieving the doping effect. When an excessively high concentration of PH3 is used during the deposition of the polysilicide layer 31, the resulting Si-PH complex is detrimental to the formation of Si-P bonds. Moreover, the excessively high concentration of PH3 hinders the crystallization of the polysilicide layer 31, resulting in a loose and porous polysilicide layer 31, which in turn reduces the effective doping of P.

[0059] To this end, the applicant discovered that by depositing the above-mentioned polysilicide and then performing plasma treatment, the doping mass concentration of the above-mentioned polysilicide is improved. At the same time, the polysilicide can maintain a better crystal structure and is not easily damaged. The polysilicide is not easy to grow a loose and porous thin film structure, thereby improving the effective doping mass concentration of the doping elements in the polysilicide, and the polysilicide maintains a high film quality, overcoming the defect that the increase in the doping mass concentration of the doping elements in the polysilicide can easily destroy the crystallization of the polysilicide.

[0060] In some embodiments, when the polycide layer 31 is n-type, the gas used in the plasma treatment is a gas containing phosphorus, and when the polycide layer 31 is p-type, the gas used in the plasma treatment is a gas containing boron.

[0061] The n-type polycrystalline silicide layer 31 is treated with a plasma containing a phosphorus element gas, so that more Si-P bonds can be formed in the n-type polycrystalline silicon oxide or polycrystalline silicon carbide layer, thereby increasing the phosphorus doping mass concentration of the polycrystalline silicon oxide or polycrystalline silicon carbide layer and improving the electrical properties of the n-type polycrystalline silicon oxide or polycrystalline silicon carbide layer.

[0062] After the p-type polysilicide layer 31 is treated with a plasma of a boron-containing gas, more BP bonds can be formed in the p-type polysilicide layer 31 , thereby increasing the boron doping concentration of the polysilicide layer 31 and improving the electrical properties of the p-type polysilicide layer 31 .

[0063] Preferably, the phosphorus-containing gas is PH3, and the boron-containing gas is one of monoborane, diborane and tetraborane.

[0064] PH3 has excellent room-temperature stability and is easy to obtain and store. As a plasma gas, PH3 can increase the phosphorus doping concentration in the n-type polysilicide layer 31 while being less likely to introduce other impurities that would negatively impact the electrical performance of the n-type polysilicide layer 31. Consequently, the increased phosphorus doping concentration leads to a positive improvement in the electrical performance of the n-type polysilicide layer 31.

[0065] The above-mentioned borane, diborane and tetraborane also have good storage stability. At the same time, when these gases are used as plasma gases, it is not easy to introduce other impurities, which is not conducive to improving the electrical properties of the p-type polysilicide layer 31. As a result, after the boron element concentration is increased, the electrical properties of the p-type polysilicide layer 31 are positively improved.

[0066] In some embodiments, the thickness of the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer is 5 nm to 150 nm.

[0067] The plasma treatment effect of the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer of the above thickness is better, and the electrical performance of the polycrystalline silicon oxide layer or polycrystalline silicon carbide layer is significantly improved, which is beneficial to improving the fill factor of the battery.

[0068] In some embodiments, the passivation contact structure further includes a lightly doped polysilicon layer, an undoped intrinsic polysilicon layer 33 and / or a heavily doped polysilicon layer 32, the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer 33 is located on the side of the polysilicide layer 31 close to the tunneling layer, with a thickness of 0nm to 80nm; the heavily doped polysilicon layer 32 is located on the side of the polysilicide layer 31 away from the tunneling layer, with a thickness of 0nm to 40nm.

[0069] The undoped intrinsic polysilicon layer 33 is the polycide layer 31 that is undoped with impurity elements. The difference between the heavily doped polysilicon layer 32 and the lightly doped polysilicon layer is the doping mass concentration. The doping mass concentration of the lightly doped polysilicon layer is between 0.05% and 2%, while the doping mass concentration of the heavily doped polysilicon layer 32 is between 1.0% and 5%. The doping mass concentration of the heavily doped polysilicon layer 32 is greater than that of the lightly doped polysilicon layer. The doping mass concentrations of the heavily doped polysilicon layer 32 and the lightly doped polysilicon layer can be set based on the ratio of the doping gas to silane flow rates. For example, if the heavily doped polysilicon layer 32 and the lightly doped polysilicon layer are n-type, PH3 is selected as the doping gas. The ratio of the doping gas to silane flow rates for the heavily doped polysilicon layer 32 is PH3:SiH4 = 5%, while the ratio for the lightly doped polysilicon layer is PH3:SiH4 = 0.5%.

[0070] The undoped intrinsic polysilicon layer 33 or the lightly doped polysilicon layer is arranged between the above-mentioned polysilicide layer 31 and the tunneling layer, which can act as a physical barrier. During the subsequent annealing process, phosphorus elements are not easily diffused into the tunneling layer and its interface, thereby reducing the risk of phosphorus elements diffusing into the tunneling layer and its interface.

[0071] The heavily doped polysilicon layer 32 has a high doping mass concentration and has better carrier collection capability. Combining the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer with the heavily doped polysilicon layer 32 is beneficial to further improve the electrical performance of the passivation contact structure, thereby improving battery efficiency.

[0072] In the passivation contact structure, there are various combinations of the undoped intrinsic polysilicon layer 33, the lightly doped polysilicon layer, the polysilicide layer 31, and the heavily doped polysilicon layer 32. For example, the polysilicide layer 31 and the lightly doped polysilicon layer can be combined, and the lightly doped polysilicon layer is located on the side of the polysilicide layer 31 close to the silicon wafer 1; the polysilicide layer 31 and the undoped intrinsic polysilicon layer 33 can be combined, and the undoped intrinsic polysilicon layer 33 is located on the side of the polysilicide layer 31 close to the silicon wafer 1; the polysilicide layer 31 and the heavily doped polysilicon layer 32 can be combined, and the heavily doped polysilicon layer 32 Located on the side of the polysilicide layer 31 facing away from the silicon wafer 1; can be a combination of an undoped intrinsic polysilicon layer 33, a polysilicide layer 31, and a heavily doped polysilicon layer 32, with the undoped intrinsic polysilicon layer 33 located on the side of the polysilicide layer 31 close to the silicon wafer 1 and the heavily doped polysilicon layer 32 located on the side of the polysilicide layer 31 facing away from the silicon wafer 1; can also be a combination of a lightly doped polysilicon layer, a polysilicide layer 31, and a heavily doped polysilicon layer 32, with the lightly doped polysilicon layer located on the side of the polysilicide layer 31 close to the silicon wafer 1 and the heavily doped polysilicon layer 32 located on the side of the polysilicide layer 31 facing away from the silicon wafer 1. A combination of the polysilicide layer 31 and the heavily doped polysilicon layer 32 is further preferred.

[0073] In some embodiments, when the passivation contact structure includes a heavily doped polysilicon layer 32, the thickness of the heavily doped polysilicon layer 32 is 5nm to 100nm; when the passivation contact structure includes a lightly doped polysilicon layer, the thickness of the lightly doped polysilicon layer is 5nm to 80nm; when the passivation contact structure includes an undoped intrinsic polysilicon layer 33, the thickness of the undoped intrinsic polysilicon 33 is 2nm to 40nm.

[0074] The heavily doped polysilicon layer 32 of the aforementioned thickness effectively enhances carrier collection, thereby improving the electrical performance of the passivation contact structure. The lightly doped polysilicon layer and the undoped intrinsic polysilicon layer 33 of the aforementioned thickness effectively block phosphorus, thereby reducing the risk of phosphorus diffusion into the tunneling layer and its interface.

[0075] In a second aspect, an embodiment of the present application provides a method for preparing a passivation contact structure as in the first aspect.

[0076] A method for preparing a passivation contact structure comprises the following steps:

[0077] A polysilicide layer 31 is deposited on the tunneling layer. The polysilicide layer 31 is a polycrystalline silicon oxide layer or a polycrystalline silicon carbide layer. The deposited polysilicide layer 31 is subjected to plasma treatment to obtain the polysilicide layer 31. The polysilicide layer 31 is n-type or p-type. When the polysilicide layer 31 is n-type, the doping mass concentration of the doping element in the polysilicide layer 31 after plasma treatment is within 1.49×1020 to 3×10 20 When the polysilicide layer 31 is p-type, the doping mass concentration of the doping element in the polysilicide layer 31 after plasma treatment is between 1.49×10 20 to 3×10 20 between.

[0078] The tunneling layer 2 of the passivated contact cell can serve as the substrate of the polysilicide layer 31. The polysilicide layer 31 is deposited on the tunneling layer 2 and subjected to plasma treatment after the polysilicide layer is deposited. This can increase the doping mass concentration of the polysilicide layer 31 and promote the crystallization of the polysilicide layer. This solves the problem that the crystallization quality of the polysilicide layer is easily reduced after the doping mass concentration in the polysilicide layer 31 is increased, thereby improving the electrical performance of the polysilicide layer 31 and further improving the cell efficiency.

[0079] In some embodiments, the plasma treatment of the polysilicide layer 31 is performed at a pressure of 0.5 mBar to 4 mBar, a power of 2000 W to 20000 W, a temperature of 350° C. to 500° C., and a time of 10 s to 200 s.

[0080] By adjusting the pressure and power of the plasma treatment, thereby controlling the intensity of the plasma and controlling the plasma treatment time, the doping mass concentration of the polysilicide layer 31 is increased while maintaining good crystallization performance. If the pressure and power of the plasma treatment are too high or the plasma treatment time is too long, the structure of the polysilicide layer 31 is easily damaged, defects in the polysilicide layer 31 are increased, and the performance of the polysilicide layer 31 is reduced. If the pressure and power of the plasma treatment are too low or the plasma treatment time is too short, the doping mass concentration of the polysilicide layer 31 is not effectively increased, and it is difficult to significantly improve the electrical performance of the polysilicide layer 31.

[0081] Exemplarily, the pressure of the plasma treatment of the polycrystalline silicide layer 31 is 0.5 mBar, 1 mBar, 1.5 mBar, 2 mBar, 2.5 mBar, 3 mBar, 3.5 mBar, 4 mBar, etc., the power is 2000 W, 4000 W, 6000 W, 8000 W, 10000 W, 15000 W, 18000 W, 20000 W, etc., the temperature is 350°C, 380°C, 420°C, 450°C, 480°C, 500°C, etc., and the time is 10s, 30s, 50s, 100s, 150s, 200s, etc.

[0082] In some embodiments, when the polysilicide layer 31 is n-type, the reaction gases for plasma treatment include PH3 and H2, and the gas flow ratio of PH3 to H2 is 100-2000:3000-30000; when the polysilicide layer 31 is p-type, the reaction gases for plasma treatment include B2H6 and H2, and the gas flow ratio of B2H6 to H2 is 100-2000:3000-30000.

[0083] Adding H2 can reduce the phosphorus content in the plasma. By controlling the ratio of the PH3 and H2 gas flows, the phosphorus concentration is controlled so that during the plasma treatment process, this concentration of phosphorus can promote the formation of Si-P bonds and improve the effective doping of phosphorus in the polysilicide layer 31 without negatively affecting the crystallization performance of the polysilicide layer 31. Excessively high phosphorus concentrations in the plasma can easily reduce the crystallization performance of the polysilicide layer 31 and loosen the network of the polysilicide layer 31, easily forming a loose and porous structure, reducing the effective doping of phosphorus and the film quality, and hindering the improvement of the electrical performance of the polysilicide layer 31. Excessively low phosphorus concentrations in the plasma can poorly improve the phosphorus doping mass concentration in the polysilicide layer 31, resulting in poor improvement in the electrical performance of the polysilicide layer 31. For example, the gas flow ratio of PH3 and H2 is 100:3000, 500:4000, 10000:20000, 20000:30000, etc.

[0084] In some embodiments, when the polycrystalline silicon oxide layer and / or the polycrystalline silicon carbide layer is n-type, the reaction gas for preparing the polycrystalline silicon oxide layer is oxygen-containing gas, SiH4, PH3 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the gas flow ratio of the reaction gas of the polycrystalline silicon oxide layer is: oxygen-containing gas:SiH4=(0.02-1.5):1, PH3:SiH4=(0.05%-5%):1, H2:SiH4=(0.5-50):1, the reaction gas for preparing the polycrystalline silicon carbide layer is CH4, SiH4, PH3 and H2, and the gas flow ratio of the reaction gas of the polycrystalline silicon carbide layer is: CH4:SiH4=(0.05-4):1, PH3:SiH4=(0.05%-5%):1, H2:SiH4=(0.5-50):1;

[0085] When the polycrystalline silicon oxide layer and / or the polycrystalline silicon carbide layer is p-type, the reaction gas for preparing the polycrystalline silicon oxide is oxygen-containing gas, SiH4, B2H6 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the gas flow ratio of the reaction gas of the polycrystalline silicon oxide layer is: oxygen-containing gas:SiH4=(0.02~1.5):1, B2H6:SiH4=(0.05%~5%):1, H2:SiH4=(0.5~50):1, the reaction gas for preparing the polycrystalline silicon carbide is CH4, SiH4, B2H6 and H2, and the gas flow ratio of the reaction gas of the polycrystalline silicon carbide layer is: CH4:SiH4=(0.05~4):1, B2H6:SiH4=(0.05%~5%):1, H2:SiH4=(0.5~50):1.

[0086] The polycrystalline silicon oxide layer and polycrystalline silicon carbide layer prepared by the above method have low parasitic absorption of light and improved short-circuit current. After the above plasma treatment, the doping mass concentration of the polycrystalline silicon oxide layer and polycrystalline silicon carbide layer is improved, and the electrical performance is also improved, which is beneficial to improving the fill factor and electrical performance of the battery.

[0087] The method for preparing the passivation contact structure further comprises the following steps:

[0088] A lightly doped polysilicon layer or an undoped intrinsic polysilicon layer 33 with a thickness of 0 nm to 80 nm is prepared on the tunneling layer 2;

[0089] forming a polycide layer 31 on the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer 33;

[0090] A heavily doped polysilicon layer 32 with a thickness of 0 nm to 40 nm is prepared on the polysilicide layer 31 to obtain a passivation contact structure, wherein at least one of the lightly doped polysilicon layer, the undoped intrinsic polysilicon layer 33 or the heavily doped polysilicon layer 32 has a thickness greater than 0 nm.

[0091] In some embodiments, when the polysilicon layer 31 is n-type, the heavily doped polysilicon layer 32 and the lightly doped polysilicon layer are n-type, and the reaction gases for preparing the n-type heavily doped polysilicon layer 32 are SiH4, PH3, and H2. The gas flow ratio of the reaction gases for preparing the n-type heavily doped polysilicon layer 32 is: PH3:SiH4=(0.1%-10%):1; H2:SiH4=(0.5-100):1. The reaction gases for preparing the n-type lightly doped intrinsic polysilicon layer 31 are SiH4, PH3, and H2. The gas flow ratio of the reaction gases for preparing the n-type lightly doped intrinsic polysilicon layer 31 is: PH3:SiH4=(0.05%-2%):1; H2:SiH4=(0.5-100):1.

[0092] When the polysilicon layer 31 is p-type, the heavily doped polysilicon layer 32 and the lightly doped polysilicon layer are p-type. The reaction gases used to prepare the p-type heavily doped polysilicon layer 32 are SiH4, B2H6, and H2. The gas flow ratio of the reaction gases for preparing the p-type heavily doped polysilicon layer 32 is: B2H6:SiH4 = (0.1% to 10%):1; H2:SiH4 = (0.5 to 100):1. The reaction gases used to prepare the p-type lightly doped intrinsic polysilicon layer 31 are SiH4, B2H6, and H2. The gas flow ratio of the reaction gases for preparing the p-type lightly doped intrinsic polysilicon layer 31 is: B2H6:SiH4 = (0.05% to 2%):1; H2:SiH4 = (0.5 to 100):1.

[0093] In some embodiments, when the polysilicide layer 31 is n-type or p-type, the reaction gases for preparing undoped intrinsic polysilicon are SiH4 and H2, and the gas flow ratio of the reaction gases for preparing undoped intrinsic polysilicon is: H2:SiH4=(0.5~100):1.

[0094] By controlling the flow rate ratio of the above reaction gases during the preparation of the heavily doped polysilicon layer 32 , it is beneficial to increase the doping mass concentration of the heavily doped polysilicon layer 32 , thereby obtaining a heavily doped polysilicon layer 32 with better carrier collection capability.

[0095] By controlling the flow rate ratio of the reaction gas in the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer 33, it is beneficial to produce a lightly doped polysilicon layer or the undoped intrinsic polysilicon layer 33 with better crystallization effect and higher density, thereby enhancing the barrier effect of the lightly doped polysilicon layer and the undoped intrinsic polysilicon layer 33 on phosphorus diffusion.

[0096] In a third aspect, an embodiment of the present application provides a solar cell.

[0097] A solar cell comprises a silicon wafer 1 and a passivation contact structure arranged on the front side, the back side or both sides of the silicon wafer 1.

[0098] The above-mentioned passivation contact structure can be used on the front side of a silicon wafer, can be used on the back side of a silicon wafer, and can also be used in a passivation contact cell having a passivation contact structure on both sides.

[0099] In some embodiments, the silicon wafer 1 is any one of an n-type single crystal silicon wafer 1, an n-type multi-crystalline silicon wafer 1, a p-type single crystal silicon wafer 1, and a p-type multi-crystalline silicon wafer 1;

[0100] When the passivation contact structure is provided on the back side of the silicon wafer 1, a passivation film layer 4 and a negative electrode are also provided on the back side of the silicon wafer 1. A polysilicide layer 31 is located between the tunneling layer 2 and the passivation film layer 4. The tunneling layer 2 is a polycrystalline silicon oxide layer with a thickness of 1nm to 2nm. The passivation film layer 4 is located on the side of the polysilicide layer 31 facing away from the silicon wafer. The passivation film layer 4 is a silicon nitride layer with a thickness of 60nm to 150nm. The negative electrode passes through the passivation film layer to form an ohmic contact with the polysilicide layer 31.

[0101] The front side of the silicon wafer may also be provided with a pn junction, an aluminum oxide layer, a silicon nitride passivation layer, and a positive electrode from the inside out. The pn junction has a junction depth of 0.3 μm to 1.5 μm, the aluminum oxide layer has a thickness of 3 nm to 15 nm, and the silicon nitride layer has a thickness of 50 nm to 180 nm. The pn junction, aluminum oxide layer, and silicon nitride passivation layer are stacked sequentially on the silicon wafer. The sintered positive electrode pierces the silicon nitride passivation layer and forms an ohmic contact with the silicon wafer 1.

[0102] When the passivation contact structure is disposed on the front side of the silicon wafer 1 , the polysilicide layer 31 is of p-type and is located on the side of the tunneling layer 2 facing away from the silicon wafer.

[0103] When the passivation contact structure is provided on both sides of the silicon wafer 1 , the front side of the silicon wafer 1 is the tunneling layer 2 and the p-type or n-type polycide layer 31 , and the back side of the silicon wafer 1 is the tunneling layer 2 and the p-type or n-type polycide layer 31 .

[0104] It should be noted that the above-mentioned passivating contact structure can be used in a variety of solar cells, such as passivating contact cells (Tunnel Oxide Passivating Contacts, TOPCon cells) and tunneling oxide passivated contact back contact cells (TBC cells). As long as they contain the above-mentioned passivating contact structure, they fall within the scope of protection of the present invention.

[0105] The method for preparing the above-mentioned passivated contact battery comprises the following steps:

[0106] Providing a silicon wafer 1 and performing post-processing;

[0107] Prepare a passivation contact structure on the front and / or back side of the processed silicon wafer 1;

[0108] After the passivation contact structure is deposited, an annealing process is performed;

[0109] A passivation film layer 4 is formed on the side of the passivation contact structure facing away from the silicon wafer 1;

[0110] The passivated contact cell was prepared by post-processing.

[0111] The technical solution of the present invention will be further described below in conjunction with more specific embodiments and drawings.

[0112] Example 1

[0113] Embodiment 1 of the present application provides a passivated contact battery, comprising:

[0114] An n-type single crystal silicon wafer 1 is diffused on the front side to form a pn junction, and then an aluminum oxide layer and a silicon nitride passivation layer are deposited. A silver positive electrode is printed. The pn junction depth is 1 μm, the aluminum oxide layer is 10 nm thick, and the silicon nitride layer is 100 nm thick. The sintered silver positive electrode pierces the silicon nitride layer and the aluminum oxide layer to form an ohmic contact with the pn junction.

[0115] The structure of the back side of the n-type single crystal silicon wafer 1 is shown in FIG1 . The back side of the n-type single crystal silicon wafer 1 is sequentially provided with a passivation contact structure, a passivation film layer 4 and a silver negative electrode, specifically including:

[0116] A tunneling layer 2 is stacked on the back of the silicon wafer 1. The tunneling layer 2 is a silicon oxide layer with a thickness of 1.5 nm.

[0117] A polycide layer 31 is stacked on the side of the tunnel layer 2 facing away from the silicon wafer 1. The polycide layer 31 is an n-type polycrystalline silicon oxide layer with a thickness of 135 nm.

[0118] A passivation film layer 4 is stacked on the side of the n-type polycrystalline silicon oxide layer facing away from the silicon wafer 1, and the passivation film layer 4 is a silicon nitride layer with a thickness of 120 nm;

[0119] The silver negative electrode is stacked on the side of the silicon nitride layer facing away from the silicon wafer 1 . The silver negative electrode passes through the passivation film layer 4 and forms an ohmic contact with the polysilicide layer 31 .

[0120] This embodiment also provides a method for preparing the above-mentioned passivated contact battery, comprising the following steps:

[0121] An n-type single crystal silicon wafer 1 is provided. After pre-cleaning, oil stains on the surface of the n-type single crystal silicon wafer 1 are removed, the cutting damage layer is removed, a clean pyramid light trapping structure is formed, boron is diffused to form a pn junction, and the glass layer coated around the edge and back is removed. The back is polished at the same time.

[0122] An n-type single crystal silicon wafer 1 is diffused on the front surface to form a pn junction, and then a front passivation layer of aluminum oxide and silicon nitride and a silver positive electrode are deposited. The silver positive electrode passes through the silicon nitride layer to form an ohmic contact with the crystalline silicon;

[0123] A tunneling layer 2 is deposited on the back side of an n-type single crystal silicon wafer 1 by plasma enhanced chemical vapor deposition;

[0124] With tunneling layer 2 as the substrate, an n-type polycrystalline silicon oxide layer was deposited on tunneling layer 2 using plasma-enhanced chemical vapor deposition (PECVD). The plasma reaction gases consisted of CO2, SiH4, PH3, and H2, with a CO2:SiH4 ratio of 1:1, PH3:SiH4 of 2.5%:1, and H2:SiH4 of 25:1. The n-type polycrystalline silicon oxide layer was then subjected to a plasma treatment using PH3 and H2 at a PH3 flow rate of 1000 sccm, an H2 flow rate of 15,000 sccm, a pressure of 2 mBar, a power of 10,000 W, a temperature of 420°C, and a treatment time of 100 seconds.

[0125] After the tunnel layer 2 and the n-type polycrystalline silicon oxide layer are deposited in sequence, an annealing process is performed;

[0126] A silicon nitride layer is prepared on the n-type polycrystalline silicon oxide layer, and a metal silver negative electrode is prepared on the silicon nitride layer by screen printing, so that the silver negative electrode passes through the silicon nitride layer to form an ohmic contact with the n-type polycrystalline silicon oxide layer.

[0127] Example 2

[0128] The difference from the first embodiment is that the polycide layer 31 is an n-type polycrystalline silicon carbide layer, and the thickness of the n-type polycrystalline silicon carbide layer is 135 nm. When the n-type polycrystalline silicon carbide layer is deposited using plasma-enhanced chemical vapor deposition, the plasma reactant gases are CH4, SiH4, PH3, and H2. The gas flow ratio of the reactant gases for the silicon carbide layer is: CH4:SiH4 = 2:1, PH3:SiH4 = 2.5%:1, and H2:SiH4 = 25:1. All other aspects remain the same as the first embodiment.

[0129] Example 3

[0130] The difference from the first embodiment is that when the n-type polycrystalline silicon oxide layer is subjected to plasma treatment, the pressure of the plasma treatment is 0.2 mBar and the power is 1000 W. The rest is the same as the first embodiment.

[0131] Example 4

[0132] The difference from the first embodiment is that when the plasma treatment is performed on the n-type polycrystalline silicon oxide layer, the pressure of the plasma treatment is 5 mBar and the power is 25000 W. The rest is consistent with the first embodiment.

[0133] Example 5

[0134] The difference from Example 1 is that an n-type heavily doped polysilicon layer 32 is added between the n-type polycrystalline silicon oxide layer and the silicon nitride layer. The structure of the n-type single crystal silicon wafer 1 and its back surface in the passivated contact cell of Example 5 is shown in FIG2 , wherein the thickness of the n-type polycrystalline silicon oxide layer is 80 nm, and the thickness of the n-type heavily doped polysilicon layer 32 is 55 nm. The preparation method of the n-type heavily doped polysilicon layer 32 is as follows:

[0135] The n-type heavily doped polysilicon layer 32 is deposited by plasma enhanced chemical vapor deposition. The plasma reaction gases are SiH4, PH3 and H2. The gas flow ratio of the reaction gases of the heavily doped polysilicon layer 32 is: PH3:SiH4=5%:1; H2:SiH4=50:1.

[0136] After the tunneling layer 2, the n-type polycrystalline silicon oxide layer and the heavily doped polycrystalline silicon layer 32 are deposited, an annealing process is performed;

[0137] A silicon nitride layer is formed on the n-type heavily doped polysilicon layer 32 .

[0138] The rest remains the same as in Example 1.

[0139] Example 6

[0140] The difference from Example 5 is that: with the tunneling layer 2 as the substrate, an n-type undoped intrinsic polycrystalline silicon layer 33 is added between the tunneling layer 2 and the n-type polycrystalline silicon oxide layer. The structure of the n-type single crystal silicon wafer 1 and its back side in the passivated contact cell of Example 6 is shown in Figure 3, wherein the thickness of the n-type undoped intrinsic polycrystalline silicon layer 33 is 20 nm, the thickness of the n-type polycrystalline silicon oxide layer is 60 nm, and the thickness of the n-type heavily doped polycrystalline silicon layer 32 is 55 nm.

[0141] The preparation method of the n-type undoped intrinsic polysilicon layer 33 and the n-type polycrystalline silicon oxide layer is as follows:

[0142] With the tunneling layer 2 as the substrate, an undoped intrinsic polysilicide layer 33 is deposited on the tunneling layer 2 by plasma enhanced chemical vapor deposition. The gases used in the plasma reaction are SiH4 and H2, and the gas flow ratio of SiH4 to H2 is: H2:SiH4=50:1.

[0143] An n-type polycrystalline silicon oxide layer was deposited on the undoped intrinsic polycrystalline silicon layer 33 using plasma-enhanced chemical vapor deposition. The plasma reaction gases were CO2, SiH4, PH3, and H2, with a CO2:SiH4 ratio of 1:1, PH3:SiH4 of 2.5%:1, and H2:SiH4 of 25:1. The n-type polycrystalline silicon oxide layer was then subjected to a plasma treatment using PH3 and H2, with a PH3 flow rate of 1000 sccm, an H2 flow rate of 15,000 sccm, a pressure of 2 mBar, a power of 10,000 W, a temperature of 420°C, and a treatment time of 100 seconds.

[0144] After the tunneling layer 2, the n-type undoped intrinsic polysilicon layer 33, the n-type polycrystalline silicon oxide layer and the heavily doped polysilicon layer 32 are deposited, an annealing process is performed;

[0145] A silicon nitride layer is formed on the n-type heavily doped polysilicon layer 32 .

[0146] The rest remains the same as in Example 5.

[0147] Example 7

[0148] The difference from Example 5 is that: with the tunneling layer 2 as the substrate, a lightly doped n-type polycrystalline silicide layer 31 is added between the tunneling layer 2 and the n-type polycrystalline silicon oxide layer, wherein the thickness of the lightly doped n-type polycrystalline silicide layer 31 is 20 nm, the thickness of the n-type polycrystalline silicon oxide layer is 60 nm, and the thickness of the n-type heavily doped polycrystalline silicon layer 32 is 55 nm.

[0149] The method for preparing the lightly doped n-type polysilicon silicide layer 31 and the n-type polycrystalline silicon oxide layer is as follows:

[0150] A lightly doped n-type polysilicide layer 31 is deposited on the tunneling layer 2 using plasma enhanced chemical vapor deposition. The ratio of the reaction gases SiH4, PH3, and H2 in the plasma is: PH3:SiH4 = 0.07%:1; H2:SiH4 = 50:1.

[0151] An n-type polycrystalline silicon oxide layer is deposited on the lightly doped n-type polycrystalline silicide layer 31 using plasma-enhanced chemical vapor deposition (PECVD). The plasma reaction gases are CO2, SiH4, PH3, and H2, where the ratio of CO2:SiH4 is 1:1, PH3:SiH4 is 2.5%:1, and H2:SiH4 is 25:1. The n-type polycrystalline silicon oxide layer is then subjected to plasma treatment using PH3 and H2. The PH3 gas flow rate is 1000 sccm, the H2 gas flow rate is 15,000 sccm, the pressure is 2 mBar, the power is 10,000 W, the temperature is 420°C, and the treatment time is 100 seconds. The n-type polycrystalline silicon oxide layer is deposited on the lightly doped n-type polycrystalline silicon oxide layer using PECVD.

[0152] After the tunneling layer 2, the lightly doped n-type intrinsic polysilicon layer 31, the n-type polycrystalline silicon oxide layer and the heavily doped polysilicon layer 32 are deposited, an annealing process is performed;

[0153] A silicon nitride layer is formed on the n-type heavily doped polysilicon layer 32 .

[0154] The rest remains the same as in Example 5.

[0155] Comparative Example 1

[0156] The difference from Example 1 is that an n-type polysilicon layer not doped with C or O is used to replace the n-type polycrystalline silicon oxide layer. After the n-type polysilicon layer not doped with C or O is deposited, no plasma treatment is performed. The method for preparing the passivation contact structure on the back side of the silicon wafer 1 is as follows:

[0157] A tunneling layer 2 is deposited on an n-type single crystal silicon wafer 1 using plasma enhanced chemical vapor deposition;

[0158] With the tunneling layer 2 as the substrate, an n-type polysilicide layer 31 not doped with C or O is deposited on the tunneling layer 2 by plasma enhanced chemical vapor deposition. The gases for the plasma reaction are PH3, SiH4 and H2, wherein PH3:SiH4=2.5%:1, H2:SiH4=25:1.

[0159] After the tunneling layer 2 and the n-type polysilicon layer 31 not doped with C or O are deposited in sequence, an annealing process is performed;

[0160] A silicon nitride layer is formed on the n-type heavily doped polysilicon layer 32 , and a metal silver negative electrode is formed on the silicon nitride layer by screen printing.

[0161] The rest remains the same as in Example 1.

[0162] Comparative Example 2

[0163] The difference from the first embodiment is that the n-type polycrystalline silicon oxide layer is not subjected to plasma treatment after deposition, and the rest is the same as the first embodiment.

[0164] Comparative Example 3

[0165] The difference from the second embodiment is that the n-type polycrystalline silicon carbide layer is not subjected to plasma treatment after deposition, and the rest is consistent with the first embodiment.

[0166] Comparative Example 4

[0167] The difference from Example 1 is that the concentration of PH3 is increased during the deposition of the n-type polycrystalline silicon oxide layer, and no plasma treatment is performed after deposition. Specifically, when preparing the n-type polycrystalline silicon oxide layer by plasma-enhanced chemical vapor deposition, the plasma reaction gases are CO2, SiH4, PH3, and H2, where the ratio of CO2:SiH4 is 1:1, PH3:SiH4 is 7%:1, and H2:SiH4 is 25:1. The rest of the ratio remains the same as Example 1.

[0168] Experiment 1

[0169] The polysilicide layers of the above embodiments and comparative examples were subjected to ECV curve tests, and the doping mass concentrations of the polysilicide layers were recorded. The test results are shown in Table 1.

[0170] Experiment 2

[0171] The electrical properties of the passivated contact cells prepared in the above embodiments and comparative examples: photoelectric conversion efficiency Eta, open circuit voltage Voc, short circuit current Isc and fill factor FF were tested, and the test value of comparative example 1 was used as the base value a, and the test value of each embodiment and comparative example was used as b. The change rate of the test value of each embodiment and comparative example compared with that of comparative example 1 was calculated as follows:

[0172] The test results are shown in Table 1.

[0173] Table 1

[0174] It can be seen from the data in Table 1 that the doping mass concentrations of the polysilicide layers of the various embodiments and comparative examples are different. On the one hand, this is because the plasma treatment conditions after the polysilicide layer is deposited are different. On the other hand, after the tunnel layer and different polysilicide layers are deposited, the subsequent annealing treatment allows the doping element phosphorus in the polysilicide layer to further diffuse, resulting in differences in the doping mass concentrations of phosphorus in the final polysilicide layer.

[0175] The FF of the passivated contact cells of Comparative Examples 2 and 3 decreased compared to that of Comparative Example 1, while Eta, Voc and Isc increased positively, proving that the use of polycrystalline silicon oxide layer or polycrystalline silicon carbide layer as the polycrystalline silicide layer can improve the short-circuit current of the passivated contact cell, but also has an adverse effect on the FF of the passivated contact cell.

[0176] The FF of Example 1 decreases less than that of Comparative Example 2, and the FF of Example 2 also decreases less than that of Comparative Example 3, and Eta, Voc, and Isc further increase positively, proving that after the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer is deposited and subjected to the above-mentioned plasma treatment, the doping mass concentration of the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer is increased, thereby significantly improving the FF and Eta, Voc, and Isc of the passivated contact cell.

[0177] A comparison of Example 1 and Comparative Example 4 shows that the phosphorus doping concentration of Example 1 is lower than that of Comparative Example 4, but the Eta, Voc, and Isc of the corresponding passivated contact cell are significantly improved compared to Comparative Example 4. The control group shown in Figure 4 is Comparative Example 4 without plasma treatment, while the experimental group is Example 1 after plasma treatment. Raman testing was performed on the passivated contact cells prepared in Example 1 and Comparative Example 4, respectively, resulting in a comparison of Raman curves as shown in Figure 4. As can be seen in Figure 4, the crystallization rate of Comparative Example 4 is 83.5%, while the crystallization rate of Example 1 is 88.1%. This shows that Example 1 has a significantly improved crystallization rate compared to Comparative Example 4, demonstrating better contact performance. This demonstrates that directly increasing the amount of PH3 during the polysilicide layer deposition process can increase the proportion of phosphorus in the polysilicide layer, but it impairs the crystallization performance of the polysilicide layer. As a result, after the phosphorus doping concentration in the polysilicide layer is increased, the Eta, Voc, and Isc of the passivated contact cell actually decrease compared to Example 1. In Example 1, plasma treatment is performed after the polysilicide layer is deposited, and the doping mass concentration of the phosphorus element is increased. The polysilicide layer prepared by this method has better crystallization quality, and the crystallization rate is significantly improved compared with the polysilicide layer in Comparative Example 4. Therefore, it has more excellent contact performance, and the Eta, Voc and Isc of the corresponding passivated contact cell are significantly improved. It can be seen that plasma treatment can solve the problem of decreased crystallization quality of the polysilicide layer that is easily caused by the polysilicide layer with a high phosphorus doping mass concentration prepared in Comparative Example 4.

[0178] The FF and of Example 3 and Example 4 decrease significantly compared with that of Example 1, which proves that under specific conditions, the plasma treatment can more significantly improve the doping mass concentration of the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer, and it is not easy to cause defects in the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer, thereby improving the FF of the passivation contact cell.

[0179] The FF of Example 5 shows a significantly lower decrease than that of Example 1, and its Eta is significantly improved, demonstrating that stacking a heavily doped polysilicon layer on the polysilicon oxide layer is beneficial for improving carrier collection capabilities, further improving the FF of the passivation contact cell, and also improving the Eta of the passivation contact cell. Based on Example 5, Examples 6 and 7 add undoped intrinsic polysilicon layers or lightly doped polysilicon layers, but the FF of Examples 6 and 7 is slightly lower than that of Example 5, demonstrating that increasing the doping concentration of the polysilicon layer is more conducive to reducing defects in the passivation contact cell and is an important factor in improving the FF of the passivation contact cell.

[0180] The above is a detailed introduction to the passivation contact structure and its preparation method, and the solar cell disclosed in the embodiments of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the passivation contact structure and its preparation method, the solar cell and its core concept of the present invention: At the same time, for general technical personnel in this field, according to the concept of the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation of the present invention.

Claims

1. A passivation contact structure, characterized in that: It includes a tunneling layer and a polysilicide layer, wherein the polysilicide layer is a polycrystalline silicon oxide layer and / or a polycrystalline silicon carbide layer; wherein, The polysilicide layer is of n-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 Up to 3×10 20 between; or, The polysilicide layer is of p-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 Up to 3×10 20 between.

2. The passivation contact structure according to claim 1, characterized in that: The polysilicide layer is a polysilicide layer that is plasma treated after being deposited.

3. The passivation contact structure according to claim 2, characterized in that: The polysilicide layer is of n-type, and the gas used in the plasma treatment is a gas containing phosphorus; or, The polysilicide layer is of p-type, and the gas used in the plasma treatment is a gas containing boron element.

4. The passivation contact structure according to any one of claims 1 to 3, characterized in that: The thickness of the polycrystalline silicon oxide layer or the polycrystalline silicon carbide layer is 5 nm to 150 nm.

5. The passivation contact structure according to any one of claims 1 to 4, characterized in that: The passivation contact structure further includes at least one of a lightly doped polysilicon layer, an undoped intrinsic polysilicon layer, and a heavily doped polysilicon layer; wherein, The lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is located on a side of the polysilicide layer close to the tunneling layer; the heavily doped polysilicon layer is located on a side of the polysilicide layer away from the tunneling layer.

6. The passivation contact structure according to claim 5, characterized in that: The thickness of the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is ≤80 nm, and the thickness of the heavily doped polysilicon layer is ≤40 nm.

7. The passivation contact structure according to claim 6, characterized in that: The passivation contact structure includes the lightly doped polysilicon layer, and the thickness of the lightly doped polysilicon layer is 5nm-80nm.

8. The passivation contact structure according to claim 6, characterized in that: The passivation contact structure includes the undoped intrinsic polysilicon layer, and the thickness of the undoped intrinsic polysilicon is 2nm-40nm.

9. The passivation contact structure according to any one of claims 6 to 8, characterized in that: The heavily doped polysilicon layer has a thickness of 5 nm to 100 nm.

10. A method for preparing a passivation contact structure, characterized in that: The preparation method comprises the following steps: The polysilicide layer is deposited on the tunneling layer, wherein the polysilicide layer is a polycrystalline silicon oxide layer or a polycrystalline silicon carbide layer, and the deposited polysilicide layer is subjected to plasma treatment; wherein, The polysilicide layer is of n-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49× 10 20 Up to 3×10 20 between; or, The polysilicide layer is of p-type, and the doping mass concentration of the doping element in the polysilicide layer is 1.49×10 20 Up to 3×10 20 between.

11. The method for preparing a passivation contact structure according to claim 10, characterized in that: The pressure of the plasma treatment is 0.5 mBar to 4 mBar, the power is 2000 W to 20000 W, the temperature is 350° C. to 500° C., and the time is 10 s to 200 s.

12. The method for preparing a passivation contact structure according to any one of claims 10 to 11, characterized in that: The polysilicide layer is of n-type, and the reaction gas for the plasma treatment includes PH3 and H2; or, The polycrystal silicide layer is of p-type, and the reaction gas of the plasma treatment includes B2H6 and H2.

13. The method for preparing a passivation contact structure according to claim 12, characterized in that: The gas flow ratio of the PH3 and the H2 is (100-2000):(3000-30000), and the gas flow ratio of the B2H6 and the H2 is (100-2000):(3000-30000).

14. The method for preparing a passivation contact structure according to any one of claims 10 to 11, characterized in that: The polycrystalline silicide layer is of n-type, the reaction gas for preparing the polycrystalline silicon oxide layer is oxygen-containing gas, SiH4, PH3 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the reaction gas for preparing the polycrystalline silicon carbide layer is CH4, SiH4, PH3 and H2; or, The polycrystalline silicide layer is of p-type, the reaction gas for preparing the polycrystalline silicon oxide is oxygen-containing gas, SiH4, B2H6 and H2, the oxygen-containing gas is one of carbon dioxide or nitrous oxide, and the reaction gas for preparing the polycrystalline silicon carbide is CH4, SiH4, B2H6 and H2.

15. The method for preparing a passivation contact structure according to claim 14, characterized in that: The polycrystalline silicide layer is of n-type, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon oxide layer is: oxygen-containing gas: SiH4 = (0.02-1.5): 1, PH3: SiH4 = (0.05%-5%): 1, H2: SiH4 = (0.5-50): 1, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon carbide layer is: CH4: SiH4 = (0.05-4): 1, PH3: SiH4 = (0.05%-5%): 1, H2: SiH4 = (0.5-50): 1; or, The polycrystalline silicide layer is of p-type, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon oxide layer is: oxygen-containing gas: SiH4 = (0.02~1.5):1, B2H6:SiH4 = (0.05%~5%):1, H2:SiH4 = (0.5~50):1, and the gas flow ratio of the reaction gas for preparing the polycrystalline silicon carbide layer is: CH4:SiH4 = (0.05~4):1, B2H6:SiH4 = (0.05%~5%):1, H2:SiH4 = (0.5~50):

1.

16. The method for preparing a passivation contact structure according to any one of claims 10 to 15, characterized in that: Before preparing the polysilicide layer, the method further includes: preparing a lightly doped polysilicon layer or an undoped intrinsic polysilicon layer on the tunneling layer; and / or, After preparing the polysilicide layer, the method further includes: preparing a heavily doped polysilicon layer on the polysilicide layer.

17. The method for preparing a passivation contact structure according to claim 16, characterized in that: The thickness of the lightly doped polysilicon layer or the undoped intrinsic polysilicon layer is ≤80nm, and the thickness of the heavily doped polysilicon layer is ≤40nm.

18. The method for preparing a passivation contact structure according to any one of claims 16 to 17, characterized in that: The polysilicide layer is of n-type, the heavily doped polysilicon layer or the lightly doped polysilicon layer is of n-type, the reaction gas for preparing the heavily doped polysilicon layer is SiH4, PH3 and H2, and the reaction gas for preparing the lightly doped intrinsic polysilicide layer is SiH4, PH3 and H2; The polysilicon layer is of p-type, the heavily doped polysilicon layer or the lightly doped polysilicon layer is of p-type, the reaction gases for preparing the p-type heavily doped polysilicon layer are SiH4, B2H6 and H2, and the reaction gases for preparing the p-type lightly doped intrinsic polysilicon layer are SiH4, B2H6 and H2.

19. The method for preparing a passivation contact structure according to claim 18, characterized in that: The gas flow ratio of the reaction gas for preparing the n-type heavily doped polysilicon layer is: PH3:SiH4=(0.1%-10%):1; H2:SiH4=(0.5-100):1; The gas flow ratio of the reaction gas for preparing the n-type lightly doped intrinsic polysilicide layer is PH3:SiH4=(0.05%-2%):1; H2:SiH4=(0.5-100):1; The gas flow ratio of the reaction gas for preparing the p-type heavily doped polysilicon layer is: B2H6:SiH4=(0.1%-10%):1; H2:SiH4=(0.5-100):1; The gas flow ratio of the reaction gas for preparing the p-type lightly doped intrinsic polysilicide layer is: B2H6:SiH4=(0.05%~2%):1; H2:SiH4=(0.5~100):

1.

20. The method for preparing a passivation contact structure according to any one of claims 16 to 19, characterized in that: The reaction gases for preparing the undoped intrinsic polysilicon are SiH4 and H2, and the gas flow ratio of the reaction gases for preparing the undoped intrinsic polysilicon is H2:SiH4=(0.5-100):

1.

21. A solar cell, characterized in that: It comprises a silicon wafer and a passivation contact structure arranged on the front and / or back side of the silicon wafer, wherein the passivation contact structure is the passivation contact structure as described in any one of claims 1 to 9, or the passivation contact structure prepared by the preparation method as described in any one of claims 7 to 13.

22. The passivated contact cell according to claim 21, characterized in that: The silicon wafer is any one of an n-type single crystal silicon wafer, an n-type multi-crystalline silicon wafer, a p-type single crystal silicon wafer and a p-type multi-crystalline silicon wafer.

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