Silicon thin film hybrid back-contact solar cell and preparation method therefor

Abstract

Provided in the present disclosure are a method for preparing a silicon thin film hybrid back-contact solar cell, and a solar cell obtained by using the method. The preparation method comprises: depositing a boron-doped silicon thin film layer on the back surface of monocrystalline silicon by means of high-density plasma chemical vapor deposition.

Description

Silicon thin film hybrid back contact solar cell and preparation method thereof

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to Chinese Patent Application No. 202411291441.1, filed on September 13, 2024, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present disclosure relates to the technical field of crystalline silicon solar cells, in particular to a preparation method of a silicon thin film hybrid back contact solar cell and a silicon thin film hybrid back contact solar cell obtained by the method. BACKGROUND

[0004] At present, the boron-doped silicon thin film layer in the amorphous-polycrystalline silicon hybrid back contact solar cell is usually prepared by plasma enhanced chemical vapor deposition (PECVD), and the boron-doped silicon thin film layer serves as a hole-selective contact layer to form a P-N junction in the polycrystalline silicon hybrid back contact solar cell.

[0005] However, in the process of preparing the boron-doped silicon thin film layer by PECVD, the negative bias causes particle bombardment damage, low doping rate, and slow deposition rate, etc., which brings about the disadvantages of high investment cost and small process window in the preparation of solar cells, and is not conducive to the industrialization of PECVD technology. Therefore, there is an urgent need to explore and apply a boron-doped silicon thin film technology that can reduce equipment cost and improve solar cell conversion efficiency. SUMMARY

[0006] The present disclosure provides a preparation method of a silicon thin film hybrid back contact solar cell, which comprises depositing a boron-doped silicon thin film layer by high-density plasma chemical vapor deposition (HDCVD, also known as inductively coupled plasma chemical vapor deposition (ICPCVD)).

[0007] In some embodiments, the boron-doped silicon thin film layer can comprise one or more of a boron-doped silicon thin film, a C-containing boron-doped silicon thin film, an O-containing boron-doped silicon thin film, and an N-containing boron-doped silicon thin film.

[0008] In some embodiments, the boron-doped silicon thin film layer can be at least one of an amorphous silicon thin film, a nanocrystalline silicon thin film, and a microcrystalline silicon thin film.

[0009] In some embodiments, the boron-doped silicon thin film layer can be a single-layer film or a multi-layer film, wherein the thickness of each film layer is 1-50 nm, and the total thickness of the boron-doped silicon thin film layer is 1-200 nm.

[0010] In some embodiments, in a high-density plasma chemical vapor deposition process, a boron-doped silicon thin film layer including a single-layer or multi-layer structure is formed by high-density plasma chemical vapor deposition using silane, borane, carbon dioxide, methane and hydrogen as process gases; the volume ratio of other gases to silane in the process gas is in the range of 0.1-100, the process pressure is in the range of 0.2-50 mbar, the deposition temperature is in the range of 30°C-500°C, and the radio frequency power density is in the range of 0.5-20 mW / cm 2 .

[0011] The high-density plasma chemical vapor deposition process can have the following operation modes.

[0012] Mode 1): Under plasma glow, a boron-doped silicon thin film is deposited on the back surface of a single crystal silicon wafer after a previous process using a mixed gas of silane, borane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100; the deposition temperature is in the range of 30°C-500°C, the time is 1-10 minutes; the process pressure is 0.2-50 mbar, and the radio frequency power density is 0.5-20 mW / cm 2 .

[0013] Mode 2): Under plasma glow, an oxygen-containing boron-doped silicon thin film is deposited on the back surface of a single crystal silicon wafer after a previous process using a mixed gas of silane, borane, carbon dioxide and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100, and the volume ratio of CO2 / SiH4 is in the range of 0.1-100; the deposition temperature is in the range of 30°C-500°C, the time is 1-10 minutes; the process pressure is 0.2-50 mbar, and the radio frequency power density is 0.5-20 mW / cm 2 .

[0014] Mode 3): Under plasma glow, an intrinsic amorphous silicon thin film is deposited on the back surface of a single crystal silicon wafer after a previous process using a mixed gas of silane and hydrogen; the volume ratio of the mixed gas H2 / SiH4 is in the range of 0.1-100; the deposition temperature is in the range of 30°C-500°C, the time is 1-10 minutes; the thickness of the intrinsic amorphous silicon thin film is 1-15 nm; the process pressure is 0.2-50 mbar, and the radio frequency power density is 0.5-20 mW / cm 2 .

[0015] Deposition of boron-doped silicon thin film using a mixed gas of silane, borane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 .

[0016] Method 4): deposition of intrinsic amorphous silicon thin film on the back surface of the single crystal silicon completed with the previous process using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the thickness of the intrinsic amorphous silicon thin film being 1-15 nm; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0017] Deposition of oxygen-containing boron-doped silicon thin film using a mixed gas of silane, borane, carbon dioxide and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100, the volume ratio of CO2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 .

[0018] Method 5): deposition of intrinsic amorphous silicon thin film on the back surface of the single crystal silicon completed with the previous process using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the thickness of the intrinsic amorphous silicon thin film being 1-15 nm; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0019] Deposition of oxygen-containing boron-doped silicon thin film using a mixed gas of silane, borane, carbon dioxide and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100, the volume ratio of CO2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0020] The boron-doped silicon thin film is deposited using a mixed gas of silane, borane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30°C-500°C, the time is 1-10 minutes; the process pressure is 0.2-50 mbar, the radio frequency power density is 0.5-20 mW / cm 2 .

[0021] The intrinsic amorphous silicon thin film is deposited on the single crystal silicon back surface using a mixed gas of silane and hydrogen under plasma glow, the volume ratio of the mixed gas H2 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30°C-500°C, the time is 1-10 minutes; the intrinsic amorphous silicon thin film thickness is 1-15 nm; the process pressure is 0.2-50 mbar, the radio frequency power density is 0.5-20 mW / cm 2 ;

[0022] The carbon-containing boron-doped silicon thin film is deposited using a mixed gas of silane, borane, methane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100, the volume ratio of CH4 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30°C-500°C, the time is 1-10 minutes; the process pressure is 0.2-50 mbar, the radio frequency power density is 0.5-20 mW / cm 2 ;

[0023] The boron-doped silicon thin film is deposited using a mixed gas of silane, borane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30°C-500°C, the time is 1-10 minutes; the process pressure is 0.2-50 mbar, the radio frequency power density is 0.5-20 mW / cm 2 .

[0024] In the preparation method of the silicon thin film hybrid back contact solar cell, after the etching, polishing and cleaning of the single crystal silicon wafer, the deposition of the tunneling oxide layer and the phosphorus-doped amorphous silicon thin film and other previous processes are completed, the boron-doped silicon thin film layer is deposited.

[0025] The silicon thin film hybrid back contact solar cell provided by the present disclosure has a boron-doped silicon thin film layer deposited by using the high-density plasma chemical vapor deposition technology. BRIEF DESCRIPTION OF DRAWINGS

[0026] FIG. 1 is a flow chart of the preparation method of the silicon thin film hybrid back contact solar cell according to the present disclosure.

[0027] Figure 2 is a structural diagram of a silicon thin film hybrid back contact solar cell according to the present disclosure. DETAILED DESCRIPTION

[0028] In order to make the skilled in the art better understand the technical solutions of the present disclosure, the technical solutions of the present disclosure are described in detail below in combination with the drawings.

[0029] In the following, example embodiments will be described more fully with reference to the accompanying drawings, in which example embodiments can be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0030] In the case of no conflict, each embodiment of the present disclosure and each feature in the embodiments can be combined with each other.

[0031] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0032] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0033] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.

[0034] The present disclosure provides a method for preparing a silicon thin film hybrid back contact solar cell, which comprises depositing a boron-doped silicon thin film layer by using a high-density plasma chemical vapor deposition (HDCVD) technique. The HDCVD is also known as an inductively coupled plasma chemical vapor deposition (ICPCVD) technique.

[0035] The boron-doped silicon thin film layer comprises one or more of a boron-doped silicon thin film, a carbon (C)-containing boron-doped silicon thin film, an oxygen (O)-containing boron-doped silicon thin film, and a nitrogen (N)-containing boron-doped silicon thin film.

[0036] The boron-doped silicon thin film layer comprises at least one of an amorphous silicon thin film, a nanocrystalline silicon thin film, and a microcrystalline silicon thin film.

[0037] The boron-doped silicon thin film layer comprises a single layer or multiple layers, each layer having a thickness of 1-50 nm, and the total thickness of the boron-doped silicon thin film layer being 1-200 nm.

[0038] In the high-density plasma chemical vapor deposition process, silane, borane, carbon dioxide, methane and hydrogen are used as process gases to form a boron-doped silicon thin film layer comprising a single layer or multiple layers by high-density plasma chemical vapor deposition; the volume ratio of other gases to silane in the process gas is in the range of 0.1-100, the process pressure is in the range of 0.2-50 mbar, the deposition temperature is in the range of 30-500°C, and the radio frequency power density is in the range of 0.5-20 mW / cm 2 .

[0039] Specifically, the volume ratio of the process gases N2O, H2, CH4, N2, CO2 or Ar to SiH4 is in the range of 0.1-100, preferably 20-80, and more preferably 30-70; for example, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, etc.

[0040] The process pressure is in the range of 0.2-50 mbar, preferably 1-45 mbar, and more preferably 5-40 mbar; for example, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, 25, 27.5, 30, 32.5, 35, 37.5, 40, 42.5, 45, 47.5 mbar, etc.

[0041] The deposition temperature is in the range of 30-500°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.

[0042] The radio frequency power density is in the range of 0.5-20 mW / cm 2 , preferably 1-18 mW / cm 2 , and more preferably 5-15 W / cm 2 ; for example, 1, 2, 4, 6, 8, 10, 12, 14, 16, 18 W / cm 2 , etc.

[0043] In the method for preparing the silicon thin film hybrid back contact solar cell according to the present disclosure, the boron-doped silicon thin film layer is deposited after the completion of the front-end processes such as texturing, polishing and cleaning of the single crystal silicon wafer, deposition of the tunneling oxide layer and deposition of the phosphorus-doped amorphous silicon thin film.

[0044] The single crystal silicon can be P-type single crystal silicon or N-type single crystal silicon.

[0045] According to one embodiment of the present disclosure, referring to FIG. 1, a preparation method of a silicon thin film hybrid back contact solar cell includes the following steps:

[0046] S1, texturing and polishing an N-type silicon wafer;

[0047] S2, depositing a tunneling silicon thin film layer and a phosphorus-doped silicon thin film layer;

[0048] S3, annealing, phosphorus activation of the phosphorus-doped silicon thin film;

[0049] S4, front side film removal and texturing;

[0050] S5, front and back side deposition of a recombination passivation film layer;

[0051] S6, patterning and etching process to remove the P region silicon thin film and cleaning;

[0052] S7, depositing a boron-doped silicon thin film layer by using high-density plasma chemical vapor deposition technology;

[0053] S8, depositing a TCO layer;

[0054] S9, patterning and etching of the TCO layer and the boron-doped silicon thin film layer; and

[0055] S10, metallization to form a cell wafer.

[0056] According to another embodiment of the present disclosure, a preparation method of a silicon thin film hybrid back contact solar cell includes the following steps:

[0057] S1, texturing and polishing an N-type silicon wafer;

[0058] In the texturing step, an alkaline solution is used to remove the surface damage layer of the silicon wafer and to smooth the surface.

[0059] S2, depositing a silicon thin film layer and a phosphorus-doped silicon thin film layer;

[0060] A tunneling oxide layer and a phosphorus-doped amorphous silicon thin film are deposited by using vacuum technology, including thermal oxidation, PECVD, low pressure chemical vapor deposition (LPCVD), high temperature diffusion, magnetron sputtering, and physical vapor deposition (PVD) technology.

[0061] S3, annealing, phosphorus activation of the phosphorus-doped silicon thin film;

[0062] A high temperature annealing furnace is used to crystallize the silicon wafer, and the annealing method can be rapid thermal annealing or tube type high temperature annealing.

[0063] For example, annealing is performed by introducing N2 at a temperature of 700-1080℃ for 300-7200s. The flow rate of N2 can be 2000-80000sccm.

[0064] S4, front side film removal and texturing;

[0065] The front side of the silicon wafer is subjected to film removal and texturing. For example, the front side SiOx is removed by using a single-side film removal device, and the front surface of the silicon wafer is subjected to texturing by using an alkaline solution. The alkaline solution has a temperature of 50-100℃, and the treatment time is 1-20min.

[0066] S5, deposition of a composite passivation film layer on the front and back sides;

[0067] The composite passivation film can be deposited by resistance heating evaporation, electron beam evaporation, magnetron sputtering, PECVD, LPCVD, etc. The composite passivation film layer can be a single-layer film or a multi-layer film formed by SiOx, AlOx, SiNxOy, SiNx or MgFx. The thickness of the composite passivation film layer is 50-150nm.

[0068] S6, patterning and etching process to remove the silicon film in the P region and cleaning;

[0069] After the deposition of the composite passivation film layer, the functional region is patterned by a patterning and etching process. The patterning process includes screen printing, laser, photolithography, etc. The etching process includes wet and dry processes, such as slurry etching, chemical etching and plasma etching, etc.

[0070] For example, the silicon film in the P region and the insulating region can be removed by laser etching, and the laser power is 300-800W, and the laser spot size is 50μm×50μm to 500μm×500μm.

[0071] In the photolithography process, a dry photoresist film can be used as a mask, extreme ultraviolet light can be used as an exposure light source, NaOH can be used as a developer, and a mixed solution of HNO3 and HF can be used 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.

[0072] S7, deposition of a boron-doped silicon film layer by high-density plasma chemical vapor deposition;

[0073] The boron-doped silicon film layer is deposited by high-density plasma chemical vapor deposition, which can include the following operation modes.

[0074] Method 1): Under plasma glow discharge, a boron-doped silicon thin film is deposited on the back surface of a single-crystal silicon substrate after previous processing using a mixed gas of silane, borane, and hydrogen. The volume ratio of BH3 / SiH4 in the mixed gas is in the range of 0.1–100, and the volume ratio of H2 / SiH4 is in the range of 0.1–100. The deposition temperature is between 30℃ and 500℃, and the time is between 1 and 10 minutes. The process pressure is between 0.2 and 50 mbar, and the RF power density is between 0.5 and 20 mW / cm³. 2 .

[0075] Method 2): Under plasma glow discharge, an oxygen-containing boron-doped silicon thin film is deposited on the back surface of a single-crystal silicon substrate after the previous process is completed, using a mixed gas of silane, borane, carbon dioxide, and hydrogen. The volume ratio of BH3 / SiH4 in the mixed gas is in the range of 0.1–100, the volume ratio of H2 / SiH4 is in the range of 0.1–100, and the volume ratio of CO2 / SiH4 is in the range of 0.1–100. The deposition temperature is between 30℃ and 500℃, the time is 1–10 minutes, the process pressure is 0.2–50 mbar, and the RF power density is 0.5–20 mW / cm³. 2 .

[0076] Method 3): Under plasma glow discharge, an intrinsic amorphous silicon thin film is deposited on the back surface of a single-crystal silicon substrate after previous processing using a mixed gas of silane and hydrogen; the volume ratio of the mixed gas H2 / SiH4 is in the range of 0.1–100; the deposition temperature is between 30℃ and 500℃, and the time is 1–10 minutes; the thickness of the intrinsic amorphous silicon thin film is 1–15 nm; the process pressure is 0.2–50 mbar, and the RF power density is 0.5–20 mW / cm². 2 ;

[0077] Boron-doped silicon thin films were deposited using a mixed gas of silane, borane, and hydrogen, with a BH3 / SiH4 volume ratio and an H2 / SiH4 volume ratio ranging from 0.1 to 100. The deposition temperature ranged from 30°C to 500°C, and the deposition time was 1 to 10 minutes. The process pressure ranged from 0.2 to 50 mbar, and the RF power density ranged from 0.5 to 20 mW / cm³. 2 .

[0078] Method 4): Under plasma glow discharge, an intrinsic amorphous silicon thin film is deposited on the back surface of a single-crystal silicon substrate after previous processing using a mixed gas of silane and hydrogen; the volume ratio of the mixed gas H2 / SiH4 is in the range of 0.1–100; the deposition temperature is between 30℃ and 500℃, and the time is 1–10 minutes; the thickness of the intrinsic amorphous silicon thin film is 1–15 nm; the process pressure is 0.2–50 mbar, and the RF power density is 0.5–20 mW / cm². 2 ;

[0079] Deposition of oxygen-containing boron-doped silicon thin film using a mixed gas of silane, borane, carbon dioxide and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100, the volume ratio of CO2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 .

[0080] Method 5): deposition of intrinsic amorphous silicon thin film on the back surface of the single crystal silicon after completion of the previous process using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the thickness of the intrinsic amorphous silicon thin film being 1-15 nm; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0081] Deposition of oxygen-containing boron-doped silicon thin film using a mixed gas of silane, borane, carbon dioxide and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100, the volume ratio of CO2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0082] Deposition of boron-doped silicon thin film using a mixed gas of silane, borane and hydrogen, the volume ratio of the mixed gas BH3 / SiH4 being in the range of 0.1-100, the volume ratio of H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 .

[0083] Method 6): deposition of intrinsic amorphous silicon thin film on the back surface of the single crystal silicon after completion of the previous process using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 being in the range of 0.1-100; the deposition temperature being between 30°C-500°C, the time being 1-10 minutes; the thickness of the intrinsic amorphous silicon thin film being 1-15 nm; the process pressure being 0.2-50 mbar, the radio frequency power density being 0.5-20 mW / cm 2 ;

[0084] Carbon-containing boron-doped silicon thin films were deposited using a mixed gas of silane, borane, methane, and hydrogen. The volume ratios of the mixed gas (BH3 / SiH4, H2 / SiH4, and CH4 / SiH4) were in the range of 0.1–100. The deposition temperature ranged from 30°C to 500°C, and the deposition time ranged from 1 to 10 minutes. The process pressure ranged from 0.2 to 50 mbar, and the RF power density ranged from 0.5 to 20 mW / cm³. 2 ;

[0085] Boron-doped silicon thin films were deposited using a mixed gas of silane, borane, and hydrogen, with a BH3 / SiH4 volume ratio and an H2 / SiH4 volume ratio ranging from 0.1 to 100. The deposition temperature ranged from 30°C to 500°C, and the deposition time was 1 to 10 minutes. The process pressure ranged from 0.2 to 50 mbar, and the RF power density ranged from 0.5 to 20 mW / cm³. 2 .

[0086] A boron-doped silicon thin film layer can be deposited according to any of the methods 1) to 6) above.

[0087] S8, deposited TCO layer;

[0088] TCO materials can be transparent conductive thin film materials such as ITO, IWO, ITiO, IMO, IO, and AZO; TCO layers can be composed of single-layer or multi-layer films. The thickness of the TCO layer ranges from 1 to 500 nm. TCO layers can be formed through methods such as resistance thermal evaporation, electron beam evaporation, magnetron sputtering, and reactive plasma deposition.

[0089] S9. Patterning and etching of the TCO layer and boron-doped silicon thin film layer;

[0090] Patterning processes include laser etching, screen printing, and photolithography. Etching processes include paste etching, laser ablation, chemical etching, and plasma etching. Insulating areas and metal contact areas are formed through patterning and etching.

[0091] S10 is metallized to form battery cells.

[0092] Metallization processes can be carried out using methods such as resistance thermal evaporation, vacuum atomic layer deposition, magnetron sputtering, chemical electroplating, screen printing, and laser pattern conversion.

[0093] For example, in the case of the resistance thermal evaporation method, the deposition is performed at a pressure of 1.5E-2 to 1.5E-6 Pa, a deposition power of 1 to 3000 W, a deposition pressure of 1.5E-3 to 1.5E-5 Pa, a substrate rotation speed of 10 rpm, a substrate temperature of 35 to 300°C, and a thermal evaporation temperature of 300 to 1200°C, and the deposited metal material can be Cu, Al, Ag, Ti, Ni, Pd, Au, Cr, Pt, or the like.

[0094] Then, the non-metallized area photoresist and the metal are removed by ultrasonic treatment. Acetone can be used as a solvent in the ultrasonic treatment.

[0095] The present disclosure also provides a silicon thin film hybrid back contact solar cell having a boron-doped silicon thin film layer obtained by using a high-density plasma chemical vapor deposition technique.

[0096] Referring to FIG. 2, the solar cell includes the following structures:

[0097] 1: N-type silicon wafer, 2: n+poly-Si, 3: boron-doped silicon thin film, 4: TCO, 5: composite passivation layer 1 (antireflection film 1), 6: composite passivation layer 2 (antireflection film 2), 7: SiOx, 8: N-zone metal electrode and structure, and 9: P-zone metal electrode.

[0098] The silicon thin film hybrid back contact solar cell prepared by using the preparation method of the present disclosure has the characteristics of fast deposition rate, small plasma damage, good uniformity, and high mass production feasibility, etc. due to the use of the high-density plasma chemical vapor deposition technique which simultaneously performs deposition and etching processes in the same reaction chamber. In addition, the high-density plasma chemical vapor deposition technique does not require multiple process cycles and post-deposition treatment, which is beneficial to cost reduction and efficiency improvement of the solar cell.

[0099] In order for 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 examples:

[0100] Embodiment 1

[0101] The N-type silicon wafer is textured and polished, and an alkaline solution is used in the texturing step to remove the damage layer on the surface of the silicon wafer and to smooth the surface.

[0102] A high-temperature LPCVD tube is used to introduce O2 at 600°C to form a tunneling silicon oxide SiOx with a thickness of 5 nm. After vacuumizing, H2, SiH4, and PH3 are introduced, and the temperature is raised to 675°C to deposit a phosphorus-doped amorphous silicon thin film with a thickness of 300 nm.

[0103] The phosphorus-doped silicon film is activated by phosphorus by introducing 5000sccm nitrogen into the high-temperature annealing tube, increasing the temperature from 600°C to 900°C at a rate of 10°C / min, and keeping the temperature for 30 min, and then decreasing the temperature to 700°C and taking out; thus the phosphorus-doped silicon film is activated by phosphorus.

[0104] The front surface SiOx is removed by using a single-sided film removal device, and the front surface of the silicon wafer is textured by using an alkaline solution; the alkaline solution has a temperature of 80°C, and the treatment time is 10 min.

[0105] SiNx and SiNxOy films are deposited by using PECVD technology, introducing SiH4, CO2, NH3 and H2, and the composite film layer has a thickness of 100 nm.

[0106] The silicon film in the P region and the insulating region is removed by using a laser etching method, the laser power is 500 W, and the laser spot size is 100*100 μm; and the silicon wafer is cleaned by using deionized water.

[0107] Boron-doped silicon film deposition is performed by using HDCVD, the back surface of the silicon wafer is exposed to the plasma glow, and a mixed gas of silane, borane and hydrogen is used to deposit the boron-doped silicon film; the volume ratio of the mixed gas BH3 / SiH4 is 1, and the volume ratio of H2 / SiH4 is 20; the deposition temperature is 100°C, the time is 10 minutes, the film thickness is 50 nm, the process pressure is 1 mbar, and the radio frequency power density is 5 mW / cm 2 .

[0108] An ITO layer with a thickness of 100 nm is deposited on the back surface of the silicon wafer by using a magnetron sputtering instrument, the deposition power is 200 W, and the deposition time is 10 min.

[0109] The ITO layer and the P-type functional region are patterned by using laser etching, the laser power is 500 W, and the laser spot size is 100*100 μm; and the silicon wafer is cleaned by using deionized water.

[0110] A patterned photoresist is formed by using ultraviolet exposure and photoresist technology; and the insulating film in the metallization area is opened by using a BOE mixed solution.

[0111] Metallization is performed by using a magnetron sputtering method, 1 μm of silver metal is deposited, the magnetron sputtering power is 100 W, the working gas pressure is 1E-3 mbar, and the deposition time is 10 min; then, the silicon wafer is placed in an ultrasonic instrument, acetone solution is poured into the ultrasonic instrument, ultrasonic treatment is performed for 30 minutes, the silicon wafer is taken out and dried, and a silicon thin film hybrid back contact solar cell is prepared.

[0112] Example 2

[0113] A silicon thin film hybrid back contact solar cell is prepared in the same manner as in Example 1, except that the boron-doped silicon film layer is deposited as follows:

[0114] The boron-doped silicon thin film containing oxygen was deposited using a mixture of silane, borane, carbon dioxide and hydrogen under plasma glow, with a volume ratio of BH3 / SiH4 of 20, a volume ratio of H2 / SiH4 of 50, and a volume ratio of CO2 / SiH4 of 15; the deposition temperature was 120°C, the deposition time was 8 minutes; the process pressure was 5 mbar, and the radio frequency power density was 10 mW / cm2. 2 .

[0115] Example 3

[0116] The silicon thin film hybrid back contact solar cell was prepared in the same manner as in Example 1, except that the boron-doped silicon thin film layer was deposited as follows:

[0117] The intrinsic amorphous silicon thin film was deposited using a mixture of silane and hydrogen under plasma glow, with a volume ratio of H2 / SiH4 of 15; the deposition temperature was 150°C, the deposition time was 5 minutes; the intrinsic amorphous silicon thin film thickness was 3 nm; the process pressure was 10 mbar, and the radio frequency power density was 10 mW / cm2. 2 ;

[0118] Then, the boron-doped silicon thin film containing oxygen was deposited using a mixture of silane, borane and hydrogen, with a volume ratio of BH3 / SiH4 of 30, a volume ratio of H2 / SiH4 of 50; the deposition temperature was 150°C, the deposition time was 6 minutes; the process pressure was 10 mbar, and the radio frequency power density was 20 mW / cm2. 2 .

[0119] Example 4

[0120] The silicon thin film hybrid back contact solar cell was prepared in the same manner as in Example 1, except that the boron-doped silicon thin film layer was deposited as follows:

[0121] The intrinsic amorphous silicon thin film was deposited using a mixture of silane and hydrogen under plasma glow, with a volume ratio of H2 / SiH4 of 30; the deposition temperature was 200°C, the deposition time was 3 minutes; the intrinsic amorphous silicon thin film thickness was 5 nm; the process pressure was 8 mbar, and the radio frequency power density was 15 mW / cm2. 2 ;

[0122] Then, the boron-doped silicon thin film containing oxygen was deposited using a mixture of silane, borane and hydrogen, with a volume ratio of BH3 / SiH4 of 30, a volume ratio of H2 / SiH4 of 50; the deposition temperature was 150°C, the deposition time was 6 minutes; the process pressure was 10 mbar, and the radio frequency power density was 20 mW / cm2. 2 .

[0123] Example 5

[0124] A silicon thin film hybrid back contact solar cell was prepared in the same manner as in Example 1, except that the deposition of the boron-doped silicon thin film layer was performed as follows:

[0125] An intrinsic amorphous silicon thin film was deposited using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 was 50; the deposition temperature was 300°C, and the time was 6 minutes; the thickness of the intrinsic amorphous silicon thin film was 8 nm; the process pressure was 4 mbar, and the radio frequency power density was 20 mW / cm 2 ;

[0126] Then, an oxygen-containing boron-doped silicon thin film was deposited using a mixed gas of silane, borane, carbon dioxide, and hydrogen; the volume ratio of the mixed gas BH3 / SiH4 was 50, the volume ratio of H2 / SiH4 was 70, and the volume ratio of CO2 / SiH4 was 40; the deposition temperature was 250°C, and the time was 5 minutes; the process pressure was 7 mbar, and the radio frequency power density was 10 mW / cm 2 ;

[0127] Then, a boron-doped silicon thin film was deposited using a mixed gas of silane, borane, and hydrogen; the volume ratio of the mixed gas BH3 / SiH4 was 50, and the volume ratio of H2 / SiH4 was 20; the deposition temperature was 300°C, and the time was 5 minutes; the process pressure was 8 mbar, and the radio frequency power density was 10 mW / cm 2 .

[0128] Example 6

[0129] A silicon thin film hybrid back contact solar cell was prepared in the same manner as in Example 1, except that the deposition of the boron-doped silicon thin film layer was performed as follows:

[0130] An intrinsic amorphous silicon thin film was deposited using a mixed gas of silane and hydrogen under plasma glow; the volume ratio of the mixed gas H2 / SiH4 was 60; the deposition temperature was 400°C, and the time was 3 minutes; the thickness of the intrinsic amorphous silicon thin film was 5 nm; the process pressure was 6 mbar, and the radio frequency power density was 10 mW / cm 2 ;

[0131] Then, a carbon-containing boron-doped silicon thin film was deposited using a mixed gas of silane, borane, methane, and hydrogen; the volume ratio of the mixed gas BH3 / SiH4 was 30, the volume ratio of H2 / SiH4 was 50, and the volume ratio of CH4 / SiH4 was 65; the deposition temperature was 400°C, and the time was 5 minutes; the process pressure was 15 mbar, and the radio frequency power density was 20 mW / cm 2 ;

[0132] Then, boron-doped silicon thin film is deposited using a mixed gas of silane, borane and hydrogen, with a volume ratio of BH3 / SiH4 being 60, a volume ratio of H2 / SiH4 being 30; a deposition temperature being 400℃, a deposition time being 10 minutes; a process pressure being 25mbar, and a radio frequency power density being 15mW / cm 2 .

[0133] Comparative Example 1

[0134] The silicon thin film hybrid back contact solar cell is prepared in the same manner as in Example 1, except that the boron-doped silicon thin film layer is deposited as follows:

[0135] In the plasma enhanced vapor deposition, carbon-containing boron-doped silicon thin film is deposited using a mixed gas of silane, borane, methane and hydrogen, with a volume ratio of BH3 / SiH4 being 30, a volume ratio of H2 / SiH4 being 50, and a volume ratio of CH4 / SiH4 being 65; a deposition temperature being 200℃, a deposition time being 5 minutes; a process pressure being 15mbar, and a radio frequency power density being 350mW / cm 2 .

[0136] Comparative Example 2

[0137] The silicon thin film hybrid back contact solar cell is prepared in the same manner as in Example 1, except that the boron-doped silicon thin film layer is deposited as follows:

[0138] In the magnetron sputtering deposition, boron-doped silicon target material is used, 30sccm Ar is introduced, a deposition temperature is 200℃, and a sputtering time is 8 minutes; a process pressure is 5E-3mbar, and a radio frequency power density is 350mW / cm 2 .

[0139] The performance of the cells prepared in the examples and comparative examples is tested, and the comparison of the performance of the cells is shown in Table 1 below.

[0140] Table 1: Comparison of the electrical performance of the solar cells prepared in the examples and comparative examples of the present disclosure

[0141] From the data in Table 1, it can be observed that the solar cells prepared by the present method have a significant advantage in energy conversion efficiency, with an increase of at least 0.223%, which can significantly improve the efficiency and reduce the cost.

[0142] The preparation method of the silicon thin film hybrid back contact solar cell described in the present disclosure has the characteristics of fast deposition rate, small plasma damage, good uniformity, and high feasibility for mass production, which is beneficial to the cost reduction and efficiency improvement of the solar cell.

[0143] Example embodiments have been disclosed herein and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. In some instances, it will be apparent to those skilled in the art that features, characteristics or / and elements described in connection with a particular embodiment can be used in conjunction with other embodiments unless otherwise explicitly stated. Accordingly, it will be understood that various changes in form and details can be made without departing from the scope of the disclosure as set forth in the appended claims.

Claims

1. A method of fabricating a silicon thin film hybrid back contact solar cell, comprising: The boron-doped silicon thin film layer is deposited on the back surface of the single crystal silicon by high-density plasma chemical vapor deposition.

2. The method of producing a silicon thin film hybrid back contact solar cell according to claim 1, wherein The boron-doped silicon thin film layer comprises one or more of boron-doped silicon thin film, carbon-containing boron-doped silicon thin film, oxygen-containing boron-doped silicon thin film, and nitrogen-containing boron-doped silicon thin film.

3. The method of producing a silicon thin film hybrid back contact solar cell according to claim 1, wherein, The boron-doped silicon thin film layer comprises at least one of amorphous silicon thin film, nanocrystalline silicon thin film, and microcrystalline silicon thin film.

4. The method of producing a silicon thin film hybrid back contact solar cell according to claim 1, wherein A boron-doped silicon thin film layer including a single layer or a multi-layer structure is formed by high-density plasma chemical vapor deposition using silane (SiH4), borane (BH3), carbon dioxide (CO2), methane (CH4) and hydrogen (H2) as process gases; the volume ratio of other gases to SiH4 in the process gases is in the range of 0.1 to 100, the process pressure is in the range of 0.2 to 50 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 0.5 to 20 mW / cm 2 .

5. The method of producing a silicon thin film hybrid back contact solar cell according to claim 1, wherein The boron-doped silicon thin film layer comprises a single layer or multiple layers, and the thickness of the boron-doped silicon thin film layer is 1-200 nm.

6. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein The boron-doped silicon film layer is deposited on the back surface of the single crystal silicon by high-density plasma chemical vapor deposition, including: using the mixed gas of SiH4, BH3 and H2 to deposit the boron-doped silicon film on the back surface of the single crystal silicon which has completed the previous process under the plasma glow, the volume ratio of BH3 / SiH4 in the mixed gas is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30-500℃, the time is 1-10 minutes; the process pressure is 0.2-50mbar, the radio frequency power density is 0.5-20mW / cm 2 .

7. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein A boron-doped silicon thin film layer is deposited on the back surface of a single crystal silicon wafer by high-density plasma chemical vapor deposition, including: under plasma glow, using a mixture of SiH4, BH3, CO2 and H2 to deposit an oxygen-containing boron-doped silicon thin film on the back surface of a single crystal silicon wafer after a previous process, in the mixture, the volume ratio of BH3 / SiH4 is in the range of 0.1-100, the volume ratio of H2 / SiH4 is in the range of 0.1-100, and the volume ratio of CO2 / SiH4 is in the range of 0.1-100; the deposition temperature is between 30-500℃, the time is 1-10 minutes; the process pressure is 0.2-50mbar, and the radio frequency power density is 0.5-20mW / cm 2 .

8. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein The method for depositing boron-doped silicon film on the back surface of single crystal silicon by high-density plasma chemical vapor deposition comprises the following steps: depositing intrinsic amorphous silicon film on the back surface of single crystal silicon which has completed preliminary process by using mixed gas of SiH4 and H2 under plasma glow; the volume ratio of H2 / SiH4 in the mixed gas is in the range of 0.1-100; the deposition temperature is in the range of 30-500℃, the deposition time is 1-10 minutes; the thickness of the intrinsic amorphous silicon film is 1-15nm; the process pressure is 0.2-50mbar, and the radio frequency power density is 0.5-20mW / cm 2 . A boron-doped silicon thin film is deposited using a mixed gas of SiH4, BH3 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 .

9. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein The method for depositing boron-doped silicon film on the back surface of single crystal silicon by high-density plasma chemical vapor deposition comprises the following steps: depositing intrinsic amorphous silicon film on the back surface of single crystal silicon which has completed preliminary process by using mixed gas of SiH4 and H2 under plasma glow; the volume ratio of H2 / SiH4 in the mixed gas is in the range of 0.1-100; the deposition temperature is in the range of 30-500℃, the deposition time is 1-10 minutes; the thickness of the intrinsic amorphous silicon film is 1-15nm; the process pressure is 0.2-50mbar, and the radio frequency power density is 0.5-20mW / cm 2 . A boron-doped silicon thin film containing oxygen is deposited using a mixed gas of SiH4, BH3, CO2 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, the volume ratio of H2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of CO2 / 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 .

10. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein The method for depositing boron-doped silicon film on the back surface of single crystal silicon by high-density plasma chemical vapor deposition comprises the following steps: depositing intrinsic amorphous silicon film on the back surface of single crystal silicon which has completed preliminary process by using mixed gas of SiH4 and H2 under plasma glow; the volume ratio of H2 / SiH4 in the mixed gas is in the range of 0.1-100; the deposition temperature is in the range of 30-500℃, the deposition time is 1-10 minutes; the thickness of the intrinsic amorphous silicon film is 1-15nm; the process pressure is 0.2-50mbar, and the radio frequency power density is 0.5-20mW / cm 2 . A boron-doped silicon thin film containing oxygen is deposited using a mixed gas of SiH4, BH3, CO2 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, the volume ratio of H2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of CO2 / 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 . A boron-doped silicon thin film is deposited using a mixed gas of SiH4, BH3 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 .

11. The method of producing a silicon thin film hybrid back contact solar cell according to claim 4, wherein The method for depositing boron-doped silicon film on the back surface of single crystal silicon by high-density plasma chemical vapor deposition comprises the following steps: depositing intrinsic amorphous silicon film on the back surface of single crystal silicon which has completed preliminary process by using mixed gas of SiH4 and H2 under plasma glow; the volume ratio of H2 / SiH4 in the mixed gas is in the range of 0.1-100; the deposition temperature is in the range of 30-500℃, the deposition time is 1-10 minutes; the thickness of the intrinsic amorphous silicon film is 1-15nm; the process pressure is 0.2-50mbar, and the radio frequency power density is 0.5-20mW / cm 2 . A carbon-containing boron-doped silicon thin film is deposited using a mixed gas of SiH4, BH3, CH4 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, the volume ratio of H2 / SiH4 is in the range of 0.1 to 100, and the volume ratio of CH4 / 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 . A boron-doped silicon thin film is deposited using a mixed gas of SiH4, BH3 and H2, wherein the volume ratio of BH3 / SiH4 is in the range of 0.1 to 100, 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 50 mbar, and the radio frequency power density is 0.5 to 20 mW / cm 2 .

12. The method of producing a silicon thin film hybrid back contact solar cell according to claim 1, wherein, Before the boron-doped silicon thin film layer is deposited on the back surface of the single crystal silicon by high-density plasma chemical vapor deposition, the method further comprises: The single crystal silicon wafer is subjected to etching, polishing, and cleaning, and is subjected to preliminary processes such as deposition of a tunneling oxide layer and a phosphorus-doped amorphous silicon thin film.

13. A silicon thin film hybrid back contact solar cell prepared by the preparation method of the silicon thin film hybrid back contact solar cell according to any one of claims 1 to 12.

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