CN121968784A

CN121968784A - A TBC solar cell and its preparation method

Info

Publication number: CN121968784A
Application number: CN202610143887.2A
Authority: CN
Inventors: 杨谋存; 储俊朗
Original assignee: Nanjing Tech University
Current assignee: Nanjing Tech University
Priority date: 2026-02-02
Filing date: 2026-02-02
Publication date: 2026-05-01

Abstract

This invention discloses a method for fabricating a TBC solar cell, comprising the following steps: alkaline polishing; sequential deposition of a silicon dioxide tunneling oxide layer and an intrinsic amorphous silicon layer; boron diffusion to convert to P-type polycrystalline silicon; laser patterning to prepare for N-region deposition; acid washing and alkaline polishing; sequential deposition of a silicon dioxide tunneling oxide layer and an intrinsic amorphous silicon layer again; phosphorus diffusion to convert to N-type polycrystalline silicon; removal of PSG from the front side; patterning to expose the N-type polycrystalline silicon region; alkaline texturing to form a pyramid structure and rounding treatment; acid washing of the back side while retaining the polycrystalline silicon layer; double-sided deposition of an alumina passivation layer and a silicon nitride passivation layer; laser drilling to expose the P-type and N-type polycrystalline silicon regions; metallization to form precision electrodes; and light injection to obtain the TBC solar cell. The TBC solar cell provided by this invention uses BSG & PSG as masks, and laser patterning/etching paste replaces photolithography and other mask materials, exhibiting high compatibility with existing TOPCON production lines.

Description

TBC solar cell and preparation method thereof

Technical Field

The invention relates to the technical field of solar cell manufacturing, in particular to a TBC solar cell preparation method based on laser patterning and non-in-situ doping technology.

Background

In recent years, the solar cell industry is rapidly developed, the conversion efficiency is required to be higher and higher, and BC batteries are developed and utilized by various manufacturers. BC battery (cross back contact battery) moves the front electrode grid line to the back, PN junction and metal contact are arranged in an interdigital manner, shielding of the grid line to sunlight is reduced, and conversion efficiency is improved. The structure optimization technology is a non-independent battery piece type, and can be overlapped with a P-type battery and an N-type battery to derive PBC, TBC (Tunnel Oxide Passivated Contact Back Contact), HBC and the like. At present, the main technical route package IBC, HBC, PBC, ABC, HPBC and the like have various BC battery technologies, and are the most differentiated routes in N-type batteries. The TBC battery integrates the advantages of TOPCon tunneling oxide passivation contact technology and IBC back contact structure, realizes no front grid line shielding through the P/N regions with the interdigital arrangement of the back, and remarkably improves photoelectric conversion efficiency.

The existing TBC has complex process, multiple times of mask and photoetching are needed for P/N region doping, the preparation method has complex flow and poor compatibility, the large-scale application of the TBC is limited, the steps are complicated, and the yield is low. Aiming at the problems, the invention provides a novel process integrating laser patterning, ex-situ doping and corrosion slurry localized doping, which simplifies the flow and improves the battery performance.

Disclosure of Invention

The invention aims at solving the problems in the prior art and provides a TBC solar cell preparation method based on a laser patterning and in-situ doping technology, which is particularly suitable for large-scale production of high-efficiency back contact crystalline silicon solar cells.

The invention aims at solving the problems through the following technical scheme:

a preparation method of a TBC solar cell comprises the following steps:

S1, performing alkali polishing, namely performing double-sided alkali polishing treatment on an N-type silicon wafer, removing a damaged layer and forming a high-reflection polished surface;

s2, thick oxidation, namely depositing a silicon dioxide tunneling oxide layer on the two sides of the N-type silicon wafer subjected to double-sided alkali polishing treatment, and then depositing an intrinsic amorphous silicon layer with the thickness of 230-260 nm outside the silicon dioxide tunneling oxide layer;

S3, boron expansion, namely converting the intrinsic amorphous silicon into P-type polycrystalline silicon by the boron expansion;

S4, laser patterning, namely removing the P-type polycrystalline silicon and the silicon dioxide tunneling oxide layer of the back surface set area by using laser under the condition of setting patterns, and preparing for depositing an N region;

s5, pickling and alkali polishing, namely pickling and removing laser damages on the front BSG and the back by using hydrofluoric acid, and then performing double-sided alkali polishing treatment on the silicon wafer;

S6, performing thin oxidation, namely depositing a silicon dioxide tunneling oxide layer on the two sides of the N-type silicon wafer subjected to double-sided alkali polishing treatment, and then depositing an intrinsic amorphous silicon layer of 110-120 nm outside the silicon dioxide tunneling oxide layer;

S7, phosphorus expansion, namely converting the intrinsic amorphous silicon into N-type polycrystalline silicon by phosphorus expansion;

s8, removing PSG on one side, namely removing PSG on the front side by hydrofluoric acid pickling;

S9, laser patterning or etching slurry patterning, namely removing the PSG of the back surface setting area by using laser or etching slurry to expose the N-type polysilicon area;

S10, performing alkali texturing treatment, forming pyramid structures on the front surface and the back surface, and rounding the pyramids;

s11, depositing an aluminum oxide passivation layer on two sides;

S12, double-sided deposition of a silicon nitride passivation layer;

S13, laser perforating, namely removing silicon nitride of the back P region and the back N region setting region by using laser, exposing the P-type polycrystalline silicon region and the N-type polycrystalline silicon region, forming a PN junction and forming good contact;

s14, metallization/electroplating, namely drying and sintering after metallization, electroplating to remove a mask and etching redundant parts so as to form a precise electrode;

and S15, light injection, namely performing light injection treatment on the sintered and electroplated silicon wafer to obtain the TBC solar cell.

The preparation method further comprises the testing of the step S16, wherein the testing process comprises the steps of adopting a high-precision machine vision detection system to detect surface defects and electrode integrity of the front and back surfaces of the battery, then conducting electrical performance testing under standard testing conditions, measuring parameters including short circuit current, open circuit voltage, filling factors and conversion efficiency, conducting nondestructive testing, including electroluminescence testing and photoluminescence testing, and finally conducting grading storage on the battery according to the standard according to testing results.

The alkali polishing process in the step S1 comprises the steps of placing an N-type silicon wafer with the thickness of 110-130um and the resistivity of 8-9Ω & cm into a wet groove type machine added with KOH, H ₂O₂ and additives, performing double-sided alkali polishing treatment on the N-type silicon wafer at the temperature of 70-90 ℃, removing a damaged layer, forming a high-reflection polished surface, and controlling the size of a tower foundation to be 7-8um.

The specific process of the thick oxidation in the step S2 is that the N-type silicon wafer subjected to double-sided alkali polishing treatment is placed into LPCVD equipment, oxygen is introduced according to 30000sccm/S-35000sccm/S, 800S-950S are deposited under the normal pressure of 600 ℃ to 650 ℃, a silicon dioxide tunneling oxide layer with the double-sided thickness of 1nm to 2nm is obtained, silane is introduced according to the flow rate of 1600sccm/S to 1800sccm/S after vacuumizing, 3500S to 4000S are deposited in the environment with the temperature of 600 ℃ to 630 ℃ and the pressure of 280 Mar to 310 Mar, and an intrinsic amorphous silicon layer with the thickness of 230nm to 260nm is deposited outside the silicon dioxide tunneling oxide layer.

The thin oxidation in the step S6 comprises the specific processes of putting the polished silicon wafer into LPCVD equipment, introducing oxygen according to 15000sccm/S-18000sccm/S, depositing 600S-660S under the normal pressure of 600-650 ℃ to obtain a silicon dioxide tunneling oxide layer with the thickness of 1nm-1.8nm, vacuumizing, introducing silane according to the flow rate of 1600sccm/S-1800sccm/S, depositing 1500S-1600S in the environment with the temperature of 600-630 ℃ and the pressure of 280 Mar-310 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 110nm-120nm outside the silicon dioxide tunneling oxide layer.

The back side sheet resistance after boron expansion in the step S3 is controlled to be 130 to 150 omega, and the back side sheet resistance after phosphorus expansion in the step S7 is controlled to be 40 to 50 omega.

The weight reduction of the alkali texturing treatment in the step S10 is controlled to be between 0.3g and 0.35g, and the rounding treatment in the step S10 is to adopt hydrochloric acid, ozone and hydrofluoric acid to carry out rounding treatment on the pyramid.

The thickness of the alumina passivation layer in the step S11 is 8nm-10nm, and the thickness of the silicon nitride passivation layer in the step S12 is 75nm-80nm, and the refractive index is 2.05-2.09.

The metallization in the step S14 is to print Cu/Ag slurry to the position of a laser opening by high-precision screen printing of a back electrode, and dry and sinter, the electroplating in the step S14 is to clean a substrate to form a seed layer, immerse the substrate into electrolyte containing target metal ions, reduce and deposit metal after electrifying, remove a mask, etch redundant parts and form the precision electrode.

KOH, H ₂O₂ and additives adopted in the preparation method are in conventional configuration.

The invention also provides a structure of the TBC solar cell, and the TBC solar cell is prepared by adopting the preparation method.

Compared with the prior art, the invention has the following advantages:

The preparation method takes BSG & PSG as a mask, replaces mask materials such as photoetching with laser patterning/corrosion slurry, has high compatibility with the existing TOPCON production line, avoids high-temperature diffusion by ex-situ doping, reduces the metallization cost by using silver-copper slurry, realizes good passivation effect by adding light injection, and improves open-circuit voltage and filling factor.

Drawings

In order to more clearly illustrate the detailed embodiments of the present invention or the technical solutions in the prior art, the following description will briefly explain the prior art and the flow chart of the present invention.

Fig. 1 is a flow chart of a preparation method of a TBC solar cell provided by the invention.

Detailed Description

Example embodiments will now be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus detailed descriptions thereof will be omitted.

The terms "a," "an," "the," "said" are used to indicate the presence of one or more elements/components/etc., the terms "comprising" and "having" are intended to mean that there may be additional elements/components/etc. in addition to the listed elements/components/etc.

The method for preparing the TBC solar cell comprises the following specific steps of:

S1, alkali polishing, namely placing an N-type silicon wafer with the thickness of 110-130um and the resistivity of 8 omega cm-9 omega cm into a wet groove type machine added with KOH, H ₂O₂ and additives, performing double-sided alkali polishing treatment on the N-type silicon wafer at 70-90 ℃, removing a damaged layer, forming a high-reflection polished surface, and controlling the size of a tower foundation to be 7-8um;

S2, thick oxidation, namely placing the N-type silicon wafer subjected to double-sided alkali polishing treatment into LPCVD equipment, introducing oxygen according to 30000sccm/S-35000sccm/S, depositing 800S-950S under normal pressure of 600-650 ℃ to obtain a silicon dioxide tunneling oxide layer with the double-sided thickness of 1nm-2nm, vacuumizing, introducing silane according to the flow rate of 1600sccm/S-1800sccm/S, depositing 3500S-4000S in an environment with the temperature of 600-630 ℃ and the pressure of 280 Mar-310 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 230nm-260nm outside the silicon dioxide tunneling oxide layer;

s3, boron expansion, namely converting the intrinsic amorphous silicon into P-type polycrystalline silicon by the boron expansion, decomposing boron trichloride at 800 ℃ to generate elemental boron (B), converting the intrinsic amorphous silicon into the P-type polycrystalline silicon under the action of high temperature, and controlling the back sheet resistance after the boron expansion to be 130-150 omega;

S4, laser patterning, namely removing the P-type polycrystalline silicon and the silicon dioxide tunneling oxide layer of the back surface set area by using laser under the condition of setting patterns, and preparing for depositing an N area;

s5, acid washing and alkali polishing, namely acid washing the front BSG (borosilicate glass) and the laser damage on the back by using hydrofluoric acid (HF) on a wet groove type machine, and adding KOH, H ₂O₂ and additives into the wet groove type machine to carry out alkali polishing treatment on the silicon wafer;

S6, thin oxidation, namely placing the polished silicon wafer into LPCVD equipment, introducing oxygen according to 15000sccm/S-18000sccm/S, depositing 600S-660S at the normal pressure of 600-650 ℃ to obtain a silicon dioxide tunneling oxide layer with the thickness of 1nm-1.8nm on both sides, vacuumizing, introducing silane according to the flow rate of 1600sccm/S-1800sccm/S, depositing 1500S-1600S in the environment with the temperature of 600-630 ℃ and the pressure of 280 Mar-310 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 110nm-120nm outside the silicon dioxide tunneling oxide layer;

S7, phosphorus expansion, namely converting intrinsic amorphous silicon into N-type polycrystalline silicon by phosphorus expansion, decomposing phosphorus oxychloride at 800 ℃ and reacting with the intrinsic amorphous silicon to generate elemental phosphorus (P), diffusing into a silicon substrate to form a PN junction, and controlling the back sheet resistance after phosphorus expansion to be 40-50Ω;

S8, removing PSG (phosphosilicate glass) on one side, namely removing PSG (phosphosilicate glass) on the front side by using hydrofluoric acid (HF) in an acid washing way on a wet groove type machine;

S9, patterning the laser patterning/etching slurry, namely removing a PSG (phosphosilicate glass) of a back surface setting area by using the laser/etching slurry to expose an N-type polycrystalline silicon area;

S10, performing alkali texturing treatment to form a pyramid structure on the front surface and the back surface, controlling the weight reduction to be between 0.3g and 0.35g, improving the light utilization rate, and performing rounding treatment on the pyramid by using hydrochloric acid (150 ml-200 ml) +ozone (concentration 40 ppm) +hydrofluoric acid (3L-4L) under the condition of 20 ℃ for 500S-600S;

S11, a double-sided aluminum oxide passivation layer is formed by depositing an aluminum oxide (AlOx) passivation layer with the thickness of 8nm-10nm on the front side and the back side by using ALD equipment;

s12, depositing a silicon nitride (SiNx) passivation layer with the thickness of 75nm-80nm and the refractive index of 2.05-2.09 on the aluminum oxide passivation layer through PECVD equipment;

S13, laser perforating, namely removing silicon nitride of the back P region and the back N region setting region by using laser, exposing the P-type polycrystalline silicon region and the N-type polycrystalline silicon region, forming a PN junction and forming good contact.

S14, metallization/electroplating:

metallization, namely printing Cu/Ag sizing agent to the position of a laser opening through a high-precision screen printing back electrode, and drying and sintering;

Electroplating, namely cleaning a substrate to form a seed layer (such as sputtering Cu), immersing the substrate in an electrolyte containing target metal ions (Cu ²⁺), and carrying out metal reduction deposition (such as Cu-Cu ²⁺+2e^-) after electrifying;

S15, light injection, namely performing light injection treatment on the sintered and electroplated silicon wafer to obtain a TBC solar cell, controlling the total amount and valence state of H to improve passivation performance, heating to activate H atoms in a silicon nitride passivation film, and controlling the valence state of the atoms through illumination to enable the atoms to be combined with a composite center (defect) at a P+ emitter and an N type substrate to form a non-composite center, so that a good passivation effect is finally realized, and the purpose of improving Voc and FF is achieved, thereby improving efficiency.

S16, testing, namely adopting a high-precision machine vision detection system to detect surface defects and electrode integrity of the front and back sides of the TBC solar cell, then carrying out electrical performance testing under standard testing conditions (AM1.5G, 1000W/m ² and 25+/-1 ℃), measuring parameters including short circuit current, open circuit voltage, filling factor and conversion efficiency, then carrying out nondestructive detection including Electroluminescence (EL) detection and Photoluminescence (PL) detection, and finally carrying out grading storage on the cell according to the standard according to the testing result.

Example 1

The preparation method of the TBC solar cell comprises the following specific steps:

S1, alkali polishing, namely placing an N-type silicon wafer with the thickness of 110um and the resistivity of 8 omega cm-9 omega cm into a wet groove type machine added with KOH, H ₂O₂ and additives, performing double-sided alkali polishing treatment on the N-type silicon wafer at the temperature of 75 ℃, removing a damaged layer, forming a high-reflection polished surface, and controlling the size of a tower foundation to be 8um;

S2, thick oxidation, namely placing the N-type silicon wafer subjected to double-sided alkali polishing treatment into LPCVD equipment, introducing oxygen according to 30000sccm/S, depositing 950S under the normal pressure of 600 ℃ to obtain a silicon dioxide tunneling oxide layer with the double-sided thickness of 2nm, introducing silane according to the flow rate of 1600sccm/S after vacuumizing, depositing 3500S in the environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 230nm outside the silicon dioxide tunneling oxide layer;

S3, boron expansion, namely converting the intrinsic amorphous silicon into P-type polycrystalline silicon by the boron expansion, decomposing boron trichloride at 800 ℃ to generate elemental boron (B), converting the intrinsic amorphous silicon into the P-type polycrystalline silicon under the action of high temperature, and controlling the back sheet resistance after the boron expansion to be 135 omega;

S6, performing thin oxidation, namely placing the polished silicon wafer into LPCVD equipment, introducing oxygen according to 15000sccm/S, depositing for 600S at normal pressure to obtain a silicon dioxide tunneling oxide layer with the thickness of 1nm on both sides, vacuumizing, introducing silane according to the flow rate of 1600sccm/S, depositing for 1500S in an environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 110nm outside the silicon dioxide tunneling oxide layer;

s7, phosphorus expansion, namely converting intrinsic amorphous silicon into N-type polycrystalline silicon by phosphorus expansion, decomposing phosphorus oxychloride at 800 ℃ and reacting with the intrinsic amorphous silicon to generate elemental phosphorus (P), diffusing into a silicon substrate to form a PN junction, and controlling the back sheet resistance after phosphorus expansion to be 45 omega;

S9, laser patterning, namely removing a back surface set region PSG (phosphosilicate glass) by using laser to expose an N-type polycrystalline silicon region;

s11, a double-sided aluminum oxide passivation layer is formed by depositing an 8nm aluminum oxide (AlOx) passivation layer on the front side and the back side by using ALD equipment;

S12, depositing a silicon nitride (SiNx) passivation layer with the thickness of 76nm and the refractive index of 2.05-2.09 on the aluminum oxide passivation layer through PECVD equipment;

S14, metallization, namely printing Cu/Ag slurry to a laser hole position through a high-precision screen printing back electrode, and drying and sintering;

Example two

S1, alkali polishing, namely placing an N-type silicon wafer with the thickness of 130um and the resistivity of 8 omega cm-9 omega cm into a wet groove type machine added with KOH, H ₂O₂ and additives, performing double-sided alkali polishing treatment on the N-type silicon wafer at the temperature of 85 ℃, removing a damaged layer, forming a high-reflection polished surface, and controlling the size of a tower foundation to be 7um;

S2, thick oxidation, namely placing the N-type silicon wafer subjected to double-sided alkali polishing treatment into LPCVD equipment, introducing oxygen according to 30000sccm/S, depositing 950S under the normal pressure of 600 ℃ to obtain a silicon dioxide tunneling oxide layer with the double-sided thickness of 2nm, introducing silane according to the flow rate of 1700sccm/S after vacuumizing, depositing 4000S in the environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 260nm outside the silicon dioxide tunneling oxide layer;

S6, performing thin oxidation, namely placing the polished silicon wafer into LPCVD equipment, introducing oxygen according to 15000sccm/S, depositing for 650 seconds at the normal pressure of 600 ℃ to obtain a silicon dioxide tunneling oxide layer with the thickness of 1.5nm on both sides, vacuumizing, introducing silane according to the flow rate of 1600sccm/S, depositing for 1600 seconds in the environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 115nm outside the silicon dioxide tunneling oxide layer;

S7, phosphorus expansion, namely converting the intrinsic amorphous silicon into N-type polycrystalline silicon by phosphorus expansion, decomposing phosphorus oxychloride at 800 ℃ and reacting with the intrinsic amorphous silicon to generate elemental phosphorus (P), diffusing into a silicon substrate to form a PN junction, and controlling the back sheet resistance after phosphorus expansion to be 50 omega;

S9, etching slurry patterning, namely removing a back surface set region PSG (phosphosilicate glass) by using the etching slurry to expose an N-type polycrystalline silicon region;

S11, a double-sided aluminum oxide passivation layer is formed by depositing an aluminum oxide (AlOx) passivation layer with the thickness of 9nm on the front side and the back side by using ALD equipment;

S12, depositing a silicon nitride (SiNx) passivation layer with the thickness of 78nm and the refractive index of 2.05-2.09 on the aluminum oxide passivation layer through PECVD equipment;

S14, electroplating, namely cleaning a substrate to form a seed layer (such as sputtering Cu), immersing the substrate in electrolyte containing target metal ions (Cu ²⁺), and carrying out metal reduction deposition (such as Cu-Cu ²⁺+2e^-) after electrifying;

Example III

s1, alkali polishing, namely placing an N-type silicon wafer with the thickness of 120um and the resistivity of 8 omega cm-9 omega cm into a wet groove type machine added with KOH, H ₂O₂ and additives, performing double-sided alkali polishing treatment on the N-type silicon wafer at the temperature of 75 ℃, removing a damaged layer, forming a high-reflection polished surface, and controlling the size of a tower foundation to be 8um;

s2, thick oxidation, namely placing the N-type silicon wafer subjected to double-sided alkali polishing treatment into LPCVD equipment, introducing oxygen according to 30000sccm/S, depositing for 900S at 600 ℃ under normal pressure to obtain a silicon dioxide tunneling oxide layer with the double-sided thickness of 2nm, introducing silane according to 1700sccm/S flow rate after vacuumizing, depositing 3500S in an environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 235nm outside the silicon dioxide tunneling oxide layer;

S6, performing thin oxidation, namely placing the polished silicon wafer into LPCVD equipment, introducing oxygen according to 15000sccm/S, depositing for 650 seconds at the normal pressure of 600 ℃ to obtain a silicon dioxide tunneling oxide layer with the thickness of 1.6nm on both sides, vacuumizing, introducing silane according to the flow rate of 1700sccm/S, depositing for 1600 seconds in the environment with the temperature of 610 ℃ and the pressure of 300 Mar, and depositing an intrinsic amorphous silicon layer with the thickness of 120nm outside the silicon dioxide tunneling oxide layer;

s11, a double-sided aluminum oxide passivation layer is formed by depositing an 8.5nm aluminum oxide (AlOx) passivation layer on the front side and the back side by using ALD equipment;

The test results of the TBC solar cells prepared in the above three examples are shown in table 1, and it is known from the above test data that the conversion efficiency of the TBC solar cells prepared in the third example is optimal.

Table 1 test results for three examples

In embodiments of the present invention, the term "plurality" refers to two or more, unless explicitly defined otherwise. The terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly attached, detachably attached, or integrally attached. The specific meaning of the above terms in the embodiments of the present invention will be understood by those of ordinary skill in the art according to specific circumstances.

In the description of the embodiments of the present invention, it should be understood that the directions or positional relationships indicated by the terms "upper", "lower", etc. are based on the directions or positional relationships shown in the drawings, are merely for convenience in describing the embodiments of the present invention and to simplify the description, and do not indicate or imply that the devices or units referred to must have a specific direction, be configured and operated in a specific direction, and thus should not be construed as limiting the embodiments of the present invention.

In the description of the present specification, the terms "one embodiment," "a preferred embodiment," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the embodiments of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above embodiments are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited by this, any modification made on the basis of the technical scheme according to the technical idea proposed by the present invention falls within the protection scope of the present invention, and the technology not related to the present invention can be implemented by the prior art.

Claims

1. A method for preparing a TBC solar cell, characterized in that the preparation method comprises the following steps:

S1, Alkali Polishing: Double-sided alkaline polishing of N-type silicon wafers to remove the damaged layer and form a highly reflective polished surface;

S2, Thick Oxidation: A silicon dioxide tunneling oxide layer is deposited on both sides of an N-type silicon wafer after double-sided alkaline polishing, followed by the deposition of an intrinsic amorphous silicon layer of 230nm-260nm outside the silicon dioxide tunneling oxide layer.

S3, Boron expansion: Boron expansion transforms intrinsic amorphous silicon into P-type polycrystalline silicon;

S4. Laser Patterning: With the pattern set, use a laser to remove the P-type polysilicon and silicon dioxide tunnel oxide layer in the back-side area to prepare for the deposition of the N-region.

S5. Pickling and Alkali Polishing: Use hydrofluoric acid to pickle and remove BSG on the front side and laser damage on the back side, and then perform double-sided alkaline polishing on the silicon wafer.

S6, Thin Oxidation: After double-sided alkaline polishing, a silicon dioxide tunneling oxide layer is deposited on both sides of the N-type silicon wafer, followed by the deposition of an intrinsic amorphous silicon layer of 110nm-120nm outside the silicon dioxide tunneling oxide layer.

S7. Phosphorus diffusion: Phosphorus diffusion transforms intrinsic amorphous silicon into N-type polycrystalline silicon;

S8. Single-sided PSG removal: Hydrofluoric acid pickling removes PSG from the front side;

S9. Laser patterning or etch paste patterning: Use a laser or etch paste to remove the PSG area on the back side to expose the N-type polysilicon area.

S10, Texturing to remove PSG/BSG: Alkali texturing is performed to form a pyramid structure on the front and back sides and the pyramids are rounded; hydrofluoric acid pickling removes PSG and BSG from the back side, retaining the polycrystalline silicon layer;

S11, double-sided deposited alumina passivation layer;

S12, Double-sided deposition of silicon nitride passivation layer;

S13, Laser opening: Using a laser to remove silicon nitride from the designated areas of the P and N regions on the back side, exposing the P-type polysilicon region and the N-type polysilicon region, forming a PN junction and creating good contact;

S14, Metallization/Electroplating: After metallization, drying and sintering are performed, and electroplating is used to remove the mask and etch the excess parts to form a precision electrode.

S15, Light Injection: Light injection is performed on the sintered and electroplated silicon wafer to obtain a TBC solar cell.

2. The TBC solar cell fabrication method according to claim 1, characterized in that: the fabrication method further includes the testing in step S16, the testing process being as follows: using a high-precision machine vision inspection system to detect surface defects and electrode integrity on the front and back of the cell; then performing electrical performance testing under standard test conditions, measuring parameters including short-circuit current, open-circuit voltage, fill factor, and conversion efficiency; then performing non-destructive testing, including electroluminescence detection and photoluminescence detection; finally, classifying and storing the cells according to standards based on the test results.

3. The method for preparing a TBC solar cell according to claim 1, characterized in that: the alkaline polishing process in step S1 is as follows: an N-type silicon wafer with a thickness of 110-130 μm and a resistivity of 8 Ω·cm-9 Ω·cm is placed in a wet trough mill containing KOH, _H₂O₂ _and additives, and the N-type silicon wafer is subjected to double-sided alkaline polishing at 70℃-90℃ to remove the damaged layer and form a high-reflectivity polished surface, with the base size controlled at 7-8 μm.

4. The method for preparing a TBC solar cell according to claim 1, characterized in that: the specific process of thick oxidation in step S2 is as follows: the N-type silicon wafer after double-sided alkaline polishing is placed in an LPCVD device, oxygen is introduced at a rate of 30000 sccm/s-35000 sccm/s, and atmospheric pressure at 600℃-650℃ for 800s-950s to obtain a silicon dioxide tunneling oxide layer with a thickness of 1nm-2nm on both sides. After vacuuming, silane is introduced at a flow rate of 1600 sccm/s-1800 sccm/s, and deposition is carried out in an environment with a temperature of 600℃-630℃ and a pressure of 280Mbar-310Mbar for 3500s-4000s to deposit an intrinsic amorphous silicon layer with a thickness of 230nm-260nm outside the silicon dioxide tunneling oxide layer.

5. The method for preparing a TBC solar cell according to claim 1, characterized in that: the specific process of thin oxidation in step S6 is as follows: the polished silicon wafer is placed in an LPCVD device, oxygen is introduced at a rate of 15000 sccm/s-18000 sccm/s, and atmospheric pressure at 600℃-650℃ is deposited for 600s-660s to obtain a silicon dioxide tunneling oxide layer with a thickness of 1nm-1.8nm on both sides; after vacuuming, silane is introduced at a flow rate of 1600 sccm/s-1800 sccm/s, and silane is deposited for 1500s-1600s in an environment with a temperature of 600℃-630℃ and a pressure of 280Mbar-310Mbar to deposit an intrinsic amorphous silicon layer with a thickness of 110nm-120nm outside the silicon dioxide tunneling oxide layer.

6. The method for preparing a TBC solar cell according to claim 1, characterized in that: the back sheet resistance after boron expansion in step S3 is controlled at 130Ω-150Ω; and the back sheet resistance after phosphorus expansion in step S7 is controlled at 40Ω-50Ω.

7. The method for preparing a TBC solar cell according to claim 1, characterized in that: the weight loss of the alkaline texturing treatment in step S10 is controlled between 0.3g and 0.35g; the rounding treatment in step S10 is performed by rounding the pyramid with hydrochloric acid + ozone + hydrofluoric acid.

8. The method for preparing a TBC solar cell according to claim 1, characterized in that: the thickness of the alumina passivation layer in step S11 is 8nm-10nm; the thickness of the silicon nitride passivation layer in step S12 is 75nm-80nm and the refractive index is 2.05-2.09.

9. The method for preparing a TBC solar cell according to claim 1, characterized in that: the metallization in step S14 is achieved by printing a back electrode using a high-precision screen printing method, printing Cu/Ag paste onto the laser-drilled opening position, and then drying and sintering; the electroplating in step S14 involves cleaning the substrate to form a seed layer, immersing the substrate in an electrolyte containing target metal ions, and then applying an electric current to reduce and deposit the metal; removing the mask, etching the excess portion, and forming a precision electrode.

10. A TBC solar cell prepared by the preparation method according to any one of claims 1-9.