Preparation method of tunneling silicon film back contact solar cell and solar cell

Abstract

The invention provides a preparation method of a tunneling silicon thin film back contact solar cell and the solar cell prepared by the method. The preparation method comprises the step of depositing a tunneling silicon thin film layer on the back surface of monocrystalline silicon by adopting high-density plasma chemical vapor deposition. By adopting the preparation method of the tunneling silicon thin film back contact solar cell, the preparation of the tunneling silicon thin film layer can be completed in one step, atom doping can be realized, the property of the tunneling silicon thin film layer can be improved, the photoelectric conversion efficiency of a crystalline silicon solar cell can be improved, and the cost can be reduced.

Description

Technical Field

[0001] The present disclosure relates to the technical field of crystalline silicon solar cells, and in particular to a method for preparing a tunneling silicon thin film back contact solar cell, and a solar cell obtained by the preparation method. Background Art

[0002] In this technical field, thermal oxidation and plasma-enhanced technology are currently widely used to prepare tunneling oxide layers. However, the existing thermal oxidation technology generally uses a processing temperature greater than 500 degrees Celsius, which results in large energy losses and limited room for cost reduction. Secondly, the plasma-enhanced vapor deposition method uses nitrous oxide as a carrier gas. Due to the influence of bias on the plasma, it is easy to cause particle bombardment damage, and the uniformity of the film is difficult to control, which greatly affects the production line yield. Chemical nitric acid oxidation is also one of the methods for preparing tunneling layers, but it has the disadvantages of high raw material costs and high requirements for waste liquid treatment, which is not conducive to cost reduction. Therefore, it is increasingly urgent to explore and apply a tunneling layer material technology that can both reduce preparation costs and improve the conversion efficiency of solar cells to meet the needs of photovoltaic efficiency improvement and cost reduction. Summary of the invention

[0003] The present invention provides a method for preparing a tunneling silicon thin film back contact solar cell, which comprises using high density plasma chemical vapor deposition technology (HDPCVD, also known as inductively coupled plasma chemical vapor deposition technology (ICPCVD)) to deposit a tunneling silicon thin film layer on the back of single crystal silicon.

[0004] The tunneling silicon film layer is selected from one or more of a silicon oxide film, a silicon carbide multilayer film, a silicon nitride multilayer film, and a C or N doped silicon oxide layer film.

[0005] In the high-density plasma chemical vapor deposition process, silane, laughing gas, hydrogen, argon, nitrogen, carbon dioxide, methane and ammonia are used as process gases to deposit silicon oxide, oxygen-doped nano-silicon, silicon carbide and silicon nitride to form a tunneling silicon thin film layer including a single layer or a multilayer structure. The thickness of the tunneling silicon thin film layer is 1-10nm.

[0006] In the high-density plasma chemical vapor deposition process, the volume ratio of other gases in the process gas to silane is in the range of 0.1 to 100, the process pressure is 0.2 to 10 mbar, the deposition temperature is between 30° C. and 500° C., and the radio frequency power density is 1 to 500 mW / cm 2 .

[0007] The high-density plasma chemical vapor deposition process may include the following operations: using a mixed gas of silane, nitrous oxide and hydrogen to deposit a silicon oxide film on the back of a single crystal silicon, wherein the volume ratio of the mixed gas N2O / SiH4 is in the range of 0.1 to 100, and the volume ratio of H2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the radio frequency power density is 1 to 500 mW / cm 2 .

[0008] The high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; a deposition temperature between 30° C. and 500° C., for 1 to 10 minutes; a process pressure of 0.2 to 10 mbar, and a radio frequency power density of 1 to 500 mW / cm 2 .

[0009] The high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; a deposition temperature between 30° C. and 500° C., for 1 to 10 minutes; a process pressure of 0.2 to 10 mbar, and a radio frequency power density of 1 to 500 mW / cm 2 ;

[0010] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0011] The high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; a deposition temperature between 30° C. and 500° C., for 1 to 10 minutes; a process pressure of 0.2 to 10 mbar, and a radio frequency power density of 1 to 500 mW / cm 2 ;

[0012] A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm2 .

[0013] The high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; a deposition temperature between 30° C. and 500° C., for 1 to 10 minutes; a process pressure of 0.2 to 10 mbar, and a radio frequency power density of 1 to 500 mW / cm 2 ;

[0014] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0015] A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0016] The high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; a deposition temperature between 30° C. and 500° C., for 1 to 10 minutes; a process pressure of 0.2 to 10 mbar, and a radio frequency power density of 1 to 500 mW / cm 2 ;

[0017] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0018] A mixed gas of silane, carbon dioxide and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas CO2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of N2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0019] In the method for preparing a tunneling silicon thin film back contact solar cell disclosed in the present invention, a tunneling silicon thin film layer is deposited after texturing, polishing and cleaning of a single crystal silicon wafer.

[0020] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, after depositing the tunneling silicon thin film layer, the silicon thin film is deposited.

[0021] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, a post-annealing treatment is performed after depositing the silicon thin film layer.

[0022] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, functional area patterning, composite passivation film deposition and back metallization are sequentially performed after post-annealing treatment.

[0023] The present disclosure provides a tunneling silicon thin film back contact solar cell, which has a tunneling silicon thin film layer deposited by high-density plasma chemical vapor deposition technology.

[0024] The method for preparing the tunneling silicon thin film back-contact solar cell disclosed in the present invention adopts high-density plasma chemical vapor deposition technology, which simultaneously performs deposition and etching processes in the same reaction chamber, and can fill gaps below 0.5 microns, thereby making the tunneling silicon thin film layer denser and more uniform, thereby improving the photoelectric conversion efficiency of the crystalline silicon solar cell; in addition, since the high-density plasma chemical vapor deposition technology does not require multiple process cycles and post-deposition treatment, it can reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a flow chart of the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention.

[0026] Figure 2 It is a structural diagram of the tunneling silicon thin film back contact solar cell described in the present disclosure. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solution of the present disclosure, the technical solution of the present disclosure is described in detail below with reference to the accompanying drawings.

[0028] Example embodiments will be described more fully below with reference to the accompanying drawings, but the example embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, the purpose of providing these embodiments is to make the present disclosure thorough and complete and to enable those skilled in the art to fully understand the scope of the present disclosure.

[0029] In the absence of conflict, the various embodiments of the present disclosure and the various features therein may be combined with each other.

[0030] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] The terms used herein are only used to describe specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "made of" are used in this specification, the presence of the features, wholes, steps, operations, elements and / or components is specified, but the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or groups thereof is not excluded.

[0032] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted as having an idealized or overly formal meaning unless explicitly defined as such herein.

[0033] The present invention provides a method for preparing a tunneling silicon thin film back contact solar cell, which comprises using high density plasma chemical vapor deposition technology (HDPCVD, also known as inductively coupled plasma chemical vapor deposition technology (ICPCVD)) to deposit a tunneling silicon thin film layer on the back of single crystal silicon.

[0034] The tunneling silicon film layer is selected from one or more of a silicon oxide film, a silicon carbide multilayer film, a silicon nitride multilayer film, and a C or N doped silicon oxide layer film.

[0035] In the high-density plasma chemical vapor deposition process, silane, laughing gas, hydrogen, argon, nitrogen, carbon dioxide, methane and ammonia are used as process gases to deposit silicon oxide, nanocrystalline silicon oxide, silicon carbide and silicon nitride to form a tunneling silicon thin film layer including a single layer or a multilayer structure. The thickness of the tunneling silicon thin film layer is 1-5nm.

[0036] In the high-density plasma chemical vapor deposition process, the volume ratio of other gases in the process gas to silane is in the range of 0.1 to 100, the process pressure is in the range of 0.2 to 10 mbar, the deposition temperature is in the range of 30° C. to 500° C., and the radio frequency power density is in the range of 1 to 500 mW / cm 2 within the range.

[0037] Specifically, the volume ratio of process gas N2O, H2, CH4, N2, CO2 or Ar to SiH4 is in the range of 0.1 to 100, preferably 20 to 80, and more preferably 30 to 70; for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, etc.

[0038] The process pressure is in the range of 0.2 to 10 mbar, preferably 1 to 8 mbar, and more preferably 2 to 6 mbar; for example, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5 mbar, etc.

[0039] The deposition temperature is in the range of 30°C to 500°C, preferably 50-450°C, and more preferably 100-400°C; for example, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475°C, etc.

[0040] RF power density is 1~500mW / cm 2 range, preferably 50 to 400 W / cm 2 , more preferably 100 to 350 W / cm 2 ; For example, 25, 50, 75, 100, 125, 150, 175, 200, 225, 250, 275, 300, 325, 350, 375, 400, 425, 450, 475 W / cm 2 wait.

[0041] In one embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using a mixed gas of silane, nitrous oxide and hydrogen to deposit on the back of the single crystal silicon, the volume ratio of the mixed gas N2O / SiH4 is in the range of 0.1 to 100, and the volume ratio of H2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0042] In another embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, the nitrous oxide flow rate is in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0043] In another embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, the nitrous oxide flow rate is in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0044] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0045] In another embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, the nitrous oxide flow rate is in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0046] A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0047] In another embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, the nitrous oxide flow rate is in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0048] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0049] A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0050] In another embodiment of the present disclosure, the high-density plasma chemical vapor deposition process may include the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, the nitrous oxide flow rate is in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0051] The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ;

[0052] A mixed gas of silane, carbon dioxide and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas CO2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of N2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

[0053] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, the tunneling silicon thin film layer is deposited after the texturing, polishing and cleaning of the single crystal silicon wafer are completed. The single crystal silicon can be P-type single crystal silicon or N-type single crystal silicon.

[0054] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, after depositing the tunneling silicon thin film layer, the silicon thin film is deposited.

[0055] The silicon thin film may include amorphous silicon, nanocrystalline silicon and microcrystalline silicon. The silicon thin film may be an intrinsic silicon thin film, a boron-doped silicon thin film and a phosphorus-doped silicon thin film. The silicon thin film may be a single-layer film or a multi-layer film.

[0056] After the tunneling silicon thin film layer is deposited, p+ silicon thin film or n+ silicon thin film is deposited by plasma enhanced vapor deposition (PECVD), low pressure chemical vapor deposition (LPCVD), magnetron sputtering and resistance thermal evaporation.

[0057] For example, when plasma enhanced vapor deposition of p+ silicon thin film is used, the polished and cleaned silicon wafer can be placed on a graphite boat, and SiH4, BH3 and H2 are introduced under the conditions of 2-80MHz power and 100-500°C temperature to deposit and form the p+ silicon thin film. The flow rate of SiH4 can be 100-5000sccm, the flow rate of BH3 can be 100-15000sccm, and the flow rate of H2 can be 100-20000sccm.

[0058] When plasma enhanced vapor deposition of n+ silicon thin film is used, the polished and cleaned silicon wafer can be placed on a graphite boat, and SiH4, PH3 and H2 are introduced under the conditions of 2-80MHz power and 100-500℃ temperature to deposit and form n+ silicon thin film. Among them, the flow rate of SiH4 can be 100-5000sccm, the flow rate of BH3 can be 100-15000sccm, and the flow rate of H2 can be 100-20000sccm.

[0059] In the method for preparing a tunneling silicon thin film back contact solar cell disclosed in the present invention, a post-annealing treatment is performed to crystallize the silicon thin film after the silicon thin film layer is deposited.

[0060] Annealing methods may include rapid thermal annealing and tubular high temperature annealing. For example, N2 is introduced at a temperature of 700-1080°C and maintained for 300-7200 seconds for annealing. The flow rate of N2 may be 2000-80000 sccm.

[0061] In the method for preparing the tunneling silicon thin film back contact solar cell disclosed in the present invention, functional area patterning, composite passivation film deposition and back metallization are sequentially performed after post-annealing treatment.

[0062] After the annealing treatment, the silicon wafer can be patterned by laser, photolithography, silk screen printing, etc. to remove the p+ silicon film in the N region.

[0063] In the photolithography process, a photoresist dry film can be used as a mask, extreme ultraviolet light as an exposure light source, NaOH as a developer, and a mixed solution of HNO3 and HF as a wet etching solution to remove the p+ silicon film in the N region, and then acetone is used to remove the residual photoresist.

[0064] After the patterning process is completed, the front side of the silicon wafer is textured by a wet process, and then a composite passivation film is deposited on the front side and the back side of the silicon wafer.

[0065] The composite passivation film may be a stacked film or a multilayer film formed by SiOx, AlOx, SiNxOy, SiNx or MgFx, and may be deposited by resistance thermal evaporation, electron beam evaporation, magnetron sputtering, PECVD, LPCVD or the like.

[0066] After depositing the composite passivation film, the silicon wafer is patterned by laser, photolithography, silk screen printing and other methods to form a Gap insulation area.

[0067] In the photolithography process, a photoresist dry film can be used as a mask, extreme ultraviolet light as an exposure light source, NaOH as a developer, and an HF mixed solution as a wet etching solution to remove the film layer in the insulating area.

[0068] Then, a metallization process can be used to form the metal electrode of the back contact battery. In the metallization process, thermal evaporation, atomic layer deposition, magnetron sputtering, chemical plating, screen printing laser pattern conversion and other technologies can be used.

[0069] In the resistance thermal evaporation process, the gas pressure before deposition is 1E-2 to 1E-6Pa, the deposition power is 1-2000W, the deposition pressure is 1E-3 to 1E-5Pa, the stage rotation speed is 5 rpm, the substrate temperature is 25-300°C, the thermal evaporation temperature is 500-1200°C, and the deposited metal materials are Cu, Al, Ag, Ti, Ni, Pd, Au, Cr and Pt, etc.

[0070] After the metallization process is completed, the photoresist and metal in the non-metallized area can be removed by ultrasonic technology. Acetone can be used as a solvent.

[0071] According to one embodiment of the present disclosure, referring to Figure 1 The method for preparing the tunneling silicon thin film back contact solar cell comprises the following steps:

[0072] S1, N-type silicon wafer texturing and polishing;

[0073] S2, tunneling silicon thin film layer deposition;

[0074] S3, boron-doped silicon thin film layer deposition;

[0075] S4, annealing, boron activation of the boron-doped silicon thin film layer deposition;

[0076] S5, photolithography patterning to remove the N-region silicon film;

[0077] S6, tunneling silicon thin film layer deposition;

[0078] S7, deposition of phosphorus-doped silicon thin film layer;

[0079] S8, annealing to activate phosphorus on the phosphorus-doped silicon thin film layer deposition;

[0080] S9, depositing a composite passivation film on the front and back sides;

[0081] S10, photolithography and patterning to form a metal contact area; and

[0082] S11, metal evaporation and ultrasonic process are used to make solar cells.

[0083] According to another embodiment of the present disclosure, the method for preparing the tunneling silicon thin film back contact solar cell comprises the following steps:

[0084] S1, N-type silicon wafer texturing and polishing;

[0085] In the texturing step, an alkaline solution is used to remove the damaged layer on the surface of the silicon wafer and smooth the surface.

[0086] S2, tunneling silicon thin film layer deposition;

[0087] HDPCVD technology is used to introduce N2O to form a tunneling silicon thin film layer SiOx with a thickness of 0.5-5nm.

[0088] S3, boron-doped silicon thin film layer deposition;

[0089] The PECVD technology is used to deposit boron-doped amorphous silicon films by introducing SiH4, H2 and BH3.

[0090] S4, annealing to activate the boron-doped silicon thin film layer deposition;

[0091] In a tubular annealing furnace, the silicon wafer is annealed at a peak temperature of 850°C to form polycrystalline silicon.

[0092] S5, photolithography patterning to remove the N-region silicon film;

[0093] Using ultraviolet exposure and photoresist technology, a patterned photoresist is formed; using a mixed solution of HNO3 and HF to remove the N-region silicon film; and then the silicon wafer is cleaned.

[0094] S6, tunneling silicon thin film layer deposition;

[0095] HDPCVD technology is used to introduce N2O to form a tunneling silicon thin film layer SiOx with a thickness of 0.5-5nm.

[0096] S7, deposition of phosphorus-doped silicon thin film layer;

[0097] Using PECVD technology, SiH4, H2 and PH3 are introduced to deposit phosphorus-doped amorphous silicon film.

[0098] S8, annealing to activate phosphorus on the phosphorus-doped silicon thin film layer deposition;

[0099] In a tubular annealing furnace, the silicon wafer is annealed at a peak temperature of 850°C to form polycrystalline silicon.

[0100] S9, depositing a composite passivation film on the front and back sides;

[0101] PECVD technology is used to introduce SiH4, CO2, NH3 and H2 to deposit SiNx and SiNxOy films.

[0102] S10, photolithography patterning to form a metal contact area;

[0103] The patterned photoresist is formed by using UV exposure and photoresist technology; the insulating film in the metallized area is opened by using a BOE mixed solution.

[0104] S11, metal evaporation and ultrasonic process to make solar cells;

[0105] The metal is evaporated by resistive thermal evaporation to form 1 μm silver metal; the silicon wafer is placed in an ultrasonic device, an acetone solution is poured in, and ultrasonicated for 30 minutes, and the silicon wafer is taken out and dried to make a tunneling silicon thin film back contact solar cell.

[0106] The present disclosure also provides a tunneling silicon thin film back contact solar cell, which has a tunneling silicon thin film layer deposited by high-density plasma chemical vapor deposition technology.

[0107] Reference Figure 2As shown, the battery includes the following structure:

[0108] 1: N-type silicon wafer, 2: n+poly-Si, 3: p+poly-Si, 4: anti-reflection film 1, 5: anti-reflection film 2, 6: tunneling silicon thin film layer, 7: N-region metal electrode, 8: P-region metal electrode.

[0109] In order to enable those skilled in the art to more clearly understand the technical solutions provided by the embodiments of the present disclosure, the technical solutions provided by the embodiments of the present disclosure are described in detail below through specific embodiments:

[0110] Example 1

[0111] The N-type silicon wafer is textured and polished, wherein an alkaline solution is used in the texture step to remove the damaged layer on the surface of the silicon wafer and smooth the morphology.

[0112] Using HDPCVD technology, a mixed gas of silane, nitrous oxide and hydrogen is used to deposit a tunneling silicon thin film layer on the back of single crystal silicon. The volume ratio of the mixed gas N2O / SiH4 is 80, and the volume ratio of H2 / SiH4 is 60. The deposition temperature is 300°C, the time is 8 minutes, the pressure is 5mbar, and the RF power density is 300mW / cm 2 ; The thickness is 2nm.

[0113] Using PECVD technology, SiH4, H2 and BH3 are introduced to deposit boron-doped amorphous silicon film. Under the conditions of power of 50MHz and temperature of 200℃, the flow rate of SiH4 can be 1000sccm, the flow rate of BH3 can be 8000sccm, and the flow rate of H2 can be 12000sccm.

[0114] In a tubular annealing furnace, boron activation is performed on the deposited boron-doped silicon thin film layer, and the silicon wafer is annealed at a peak temperature of 850°C to form polysilicon.

[0115] Using ultraviolet exposure and photoresist technology, a patterned photoresist is formed; using a mixed solution of HNO3 and HF to remove the N-region silicon film; and then the silicon wafer is cleaned.

[0116] Using HDPCVD technology, a mixed gas of silane, nitrous oxide and hydrogen is used to deposit a tunneling silicon thin film layer on the back of single crystal silicon. The volume ratio of the mixed gas N2O / SiH4 is 70, and the volume ratio of H2 / SiH4 is 80. The deposition temperature is 250°C, the time is 5 minutes, the pressure is 4mbar, and the RF power density is 200mW / cm 2 ; Thickness is 3nm.

[0117] Using PECVD technology, SiH4, H2 and PH3 are introduced to deposit phosphorus-doped amorphous silicon film. Under the conditions of power of 60MHz and temperature of 250℃, the flow rate of SiH4 can be 2000sccm, the flow rate of BH3 can be 6000sccm, and the flow rate of H2 can be 10000sccm.

[0118] In a tubular annealing furnace, the silicon wafer is annealed at a peak temperature of 850°C to form polycrystalline silicon.

[0119] PECVD technology was used to introduce SiH4, CO2, NH3 and H2 to deposit SiNx and SiNxOy films at a deposition temperature of 400°C, a deposition time of 8 minutes and a deposition pressure of 1.5 mbar.

[0120] A patterned photoresist is formed using ultraviolet exposure and photoresist technology. A BOE mixed solution is used to open the insulating film in the metallized area. The BOE concentration ratio is 1:7 and the process time is 2 minutes.

[0121] The metal was evaporated by resistive thermal evaporation to form 1μm silver metal; the silicon wafer was placed in an ultrasonic device, and an acetone solution was poured in. The ultrasonic power was 200W and the temperature was 50°C. The silicon wafer was taken out and dried to make a tunneling silicon thin film back contact solar cell.

[0122] Example 2

[0123] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0124] The silicon oxide film was deposited on the back of the single crystal silicon using nitrous oxide with a nitrous oxide flow rate of 1200 sccm, a deposition temperature of 350°C, a deposition time of 8 minutes, a pressure of 8 mbar, and an RF power density of 350 mW / cm 2 ; The thickness is 5nm.

[0125] Example 3

[0126] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0127] The silicon oxide film was deposited on the back of the single crystal silicon using nitrous oxide with a nitrous oxide flow rate of 1500 sccm, a deposition temperature of 400°C, a deposition time of 6 minutes, a pressure of 5 mbar, and an RF power density of 250 mW / cm 2 ;Thickness is 2nm;

[0128] Then, a mixed gas of silane, methane and hydrogen was used to deposit the tunneling silicon carbide film. The volume ratio of the mixed gas CH4 / SiH4 was 60, and the volume ratio of H2 / SiH4 was 40. The deposition temperature was between 300°C and the time was 5 minutes. The pressure was 6 mbar and the RF power density was 350 mW / cm 2 ; The thickness is 4nm.

[0129] Example 4

[0130] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0131] The silicon oxide film was deposited on the back of the single crystal silicon using nitrous oxide with a nitrous oxide flow rate of 1000 sccm, a deposition temperature of 100°C, a deposition time of 8 minutes, a pressure of 6 mbar, and an RF power density of 350 mW / cm 2 ;Thickness is 3nm;

[0132] Then, a mixed gas of silane, argon and nitrogen was used to deposit the tunneling silicon nitride film. The volume ratio of the mixed gas N2 / SiH4 was 50, and the volume ratio of Ar / SiH4 was 80. The deposition temperature was 400°C, the time was 6 minutes, the pressure was 5 mbar, and the RF power density was 250 mW / cm 2 ; Thickness is 3nm.

[0133] Example 5

[0134] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0135] The silicon oxide film was deposited on the back of the single crystal silicon using nitrous oxide. The nitrous oxide flow rate was 800 sccm. The deposition temperature was 400°C for 6 minutes. The pressure was 7 mbar and the RF power density was 300 mW / cm 2 ;Thickness is 3nm;

[0136] Then, a mixed gas of silane, methane and hydrogen was used to deposit the tunneling silicon carbide film. The volume ratio of the mixed gas CH4 / SiH4 was 60, and the volume ratio of H2 / SiH4 was 80. The deposition temperature was 200°C and the time was 7 minutes. The process pressure was 9 mbar and the RF power density was 400 mW / cm 2 ;Thickness is 2nm;

[0137] Then, a mixed gas of silane, argon and nitrogen was used to deposit the tunneling silicon nitride film. The volume ratio of the mixed gas N2 / SiH4 was 80, and the volume ratio of Ar / SiH4 was 60. The deposition temperature was 200°C, the time was 8 minutes, the pressure was 5 mbar, and the RF power density was 450 mW / cm 2 ; The thickness is 4nm.

[0138] Example 6

[0139] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0140] The silicon oxide film was deposited on the back of the single crystal silicon using nitrous oxide with a nitrous oxide flow rate of 1500 sccm, a deposition temperature of 250°C, a deposition time of 8 minutes, a pressure of 6 mbar, and an RF power density of 400 mW / cm 2 ;Thickness is 3nm;

[0141] Then, a mixed gas of silane, methane and hydrogen was used to deposit the tunneling silicon carbide film. The volume ratio of the mixed gas CH4 / SiH4 was 55, and the volume ratio of H2 / SiH4 was 75. The deposition temperature was 300°C, the time was 6 minutes, the pressure was 4 mbar, and the RF power density was 300 mW / cm 2 ;Thickness is 4nm;

[0142] Then, a mixed gas of silane, carbon dioxide and nitrogen was used to deposit the tunneling silicon nitride film. The volume ratio of the mixed gas CO2 / SiH4 was 85, and the volume ratio of N2 / SiH4 was 70. The deposition temperature was 250°C, the time was 8 minutes, the pressure was 8 mbar, and the RF power density was 400 mW / cm 2 ; The thickness is 2nm.

[0143] Comparative Example 1

[0144] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0145] A thermal oxidation method is adopted, oxygen is introduced into a tubular heating furnace, the temperature is set at 600-700° C., and the process time is 5 minutes; the thickness of the tunneling silicon film layer is 5 nm.

[0146] Comparative Example 2

[0147] A tunneling silicon thin film back contact solar cell is prepared in the same manner as in Example 1, except that the deposition operation of the tunneling silicon thin film layer is as follows:

[0148] Plasma enhanced vapor chemical deposition was used, N2O was introduced as the reaction gas, the power was 20W, the set temperature was 180°C, the working pressure was 2mbar, the reaction time was 4 minutes; the thickness of the tunneling silicon film layer was 5nm.

[0149] The batteries prepared in the examples and comparative examples were subjected to performance tests, and the following Table 1 shows a comparison of the performance of each battery.

[0150] Table 1: Comparison of electrical properties of solar cells prepared in the embodiments of the present invention and the comparative examples

[0151] Number of samples Conversion efficiency % Voc_mV Isc_A FF_% Example 1 197 25.736 0.7365 13.7478 85.081 Example 2 195 25.756 0.7362 13.7468 85.085 Example 3 190 25.743 0.7368 13.7462 85.083 Example 4 195 25.738 0.7360 13.7470 85.088 Example 5 190 25.740 0.7361 13.7465 85.085 Example 6 195 25.751 0.7365 13.7475 85.082 Comparative Example 1 198 25.536 0.7355 13.7548 84.490 Comparative Example 2 195 25.432 0.7335 13.7542 84.485

[0152] It can be observed from Table 1 that the solar cells prepared by this method have obvious advantages in energy conversion efficiency, which is increased by at least 0.2%, and can significantly improve efficiency and reduce costs.

[0153] By adopting the method for preparing the tunneling silicon thin film back-contact solar cell disclosed in the present invention, the tunneling silicon thin film layer can be prepared in one step and atomic doping can be achieved, which can improve the properties of the tunneling silicon thin film layer, increase the photoelectric conversion efficiency of the crystalline silicon solar cell, and reduce the cost.

[0154] Example embodiments have been disclosed herein, and although specific terms are employed, they are used and should be interpreted only in a general illustrative sense and not for limiting purposes. In some instances, it will be apparent to those skilled in the art that, unless otherwise expressly noted, features, characteristics, and / or elements described in conjunction with a particular embodiment may be used alone or in combination with features, characteristics, and / or elements described in conjunction with other embodiments. Therefore, those skilled in the art will appreciate that various changes in form and detail may be made without departing from the scope of the present disclosure as set forth in the appended claims.

Claims

1. A method for preparing a tunneling silicon thin film back contact solar cell, which comprises depositing a tunneling silicon thin film layer on the back of a single crystal silicon by high density plasma chemical vapor deposition.

2. The method for preparing a tunneling silicon thin film back-contact solar cell according to claim 1, wherein the tunneling silicon thin film layer is selected from one or more of a silicon oxide thin film, a silicon carbide multilayer thin film, a silicon nitride multilayer thin film, and a C or N-doped silicon oxide layer thin film.

3. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: Silicon oxide, nanocrystalline silicon oxide, silicon carbide and silicon nitride are deposited using silane, nitrous oxide, hydrogen, argon, nitrogen, carbon dioxide, methane and ammonia as process gases, and a tunneling silicon thin film layer including a single layer or a multilayer structure is formed by high-density plasma chemical vapor deposition.

4. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: In the high-density plasma chemical vapor deposition process, the volume ratio of other gases in the process gas to silane is in the range of 0.1 to 100, the process pressure is 0.2 to 10 mbar, the deposition temperature is between 30° C. and 500° C., and the radio frequency power density is 1 to 500 mW / cm 2 .

5. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: The thickness of the tunneling silicon thin film layer is 1-5 nm.

6. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using a mixed gas of silane, nitrous oxide and hydrogen to deposit on the back of single crystal silicon, the volume ratio of the mixed gas N2O / SiH4 is in the range of 0.1 to 100, and the volume ratio of H2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

7. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

8. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

9. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

10. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; A mixed gas of silane, argon and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas N2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of Ar / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

11. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 3, wherein: High-density plasma chemical vapor deposition includes the following operations: using nitrous oxide to deposit a silicon oxide film on the back of a single crystal silicon, with a nitrous oxide flow rate in the range of 0 to 2000 sccm; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; The tunneling silicon carbide film is deposited using a mixed gas of silane, methane and hydrogen, with a CH4 / SiH4 volume ratio in the range of 0.1 to 100 and a H2 / SiH4 volume ratio in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 ; A mixed gas of silane, carbon dioxide and nitrogen is used to deposit a tunneling silicon nitride film, wherein the volume ratio of the mixed gas CO2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of N2 / SiH4 is in the range of 0.1 to 100; the deposition temperature is between 30°C and 500°C, and the time is 1 to 10 minutes; the process pressure is 0.2 to 10 mbar, and the RF power density is 1 to 500 mW / cm 2 .

12. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: After the single crystal silicon wafer is textured, polished and cleaned, a tunneling silicon thin film layer is deposited.

13. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: After depositing the tunneling silicon thin film layer, the silicon thin film is deposited.

14. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: A post annealing process is performed after the deposition of the silicon thin film layer.

15. The method for preparing a tunneling silicon thin film back contact solar cell according to claim 1, wherein: After the post-annealing treatment, functional area patterning, composite passivation film deposition and back metallization treatment are carried out in sequence.

16. A tunneling silicon thin film back contact solar cell, comprising a tunneling silicon thin film layer deposited by high density plasma chemical vapor deposition technology.

17. A tunneling silicon thin film back-contact solar cell, which is obtained by the preparation method of the tunneling silicon thin film back-contact solar cell according to claims 1-15.

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