TBC Battery Grooving Method, TBC Battery Preparation Method and Application

Abstract

The present invention provides a method for grooving a TBC battery, a method for manufacturing a TBC battery, and an application thereof, relating to the technical field of solar cells. The method for grooving a TBC battery comprises the following steps: sequentially preparing a first tunneling oxide layer, a P-Poly layer, and a first BSG layer on the back surface of a battery substrate, and removing the first BSG layer in a preset negative electrode region by using a first laser treatment; then performing a thermal oxidation treatment on the P-Poly layer to oxidize the P-Poly layer in the preset negative electrode region into a second BSG layer, and removing the second BSG layer and the first tunneling oxide layer in the preset negative electrode region by using a second laser treatment to obtain a battery chip with a groove in the preset negative electrode region. The present invention adopts a preparation method of laser patterning + thermal oxidation + laser patterning at the grooved position of the preset negative electrode region, and does not damage the silicon substrate.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and particularly to a grooving method for a TBC cell, a preparation method for a TBC cell, and an application thereof. Background Art

[0002] The front side of an IBC cell has no occlusion and has a higher conversion efficiency. An IBC (Interdigitated back contact) cell, also known as an interdigitated back contact cell, is characterized in that all the grid lines on the front side of the cell are transferred to the back side, reducing the occlusion of incident light, and improving the short-circuit current and conversion efficiency of the cell. The BC cell is a platform technology and can be combined with X cells using different passivation processes to form various XBC cells. For example, it can be combined with Topcon to form a TBC cell. The general process route of PECVD is: double-sided polishing - PECVD preparation of P-poly - backside patterning - polishing - PECVD preparation of N-poly - annealing - secondary patterning - cleaning + texturing - double-sided ALOx - backside SiNx - front side SiNx - printing - light injection - testing.

[0003] In the existing TBC cell, the N-region grooving is prepared by backside patterning and polishing. First, a laser is used to groove the backside BSG. Due to the limited laser energy, the P-poly and the tunneling oxide layer are retained, and then an alkaline solution is used for polishing to remove the P-poly and the tunneling oxide layer. However, at the same time, the alkaline solution will also corrode the silicon substrate. The greater the corrosion depth, the less the absorption of long-wavelength incident light, the fewer the number of photo-generated carriers, and the lower the current, ultimately resulting in a reduction in efficiency.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] One of the objectives of the present invention is to provide a grooving method for a TBC cell to at least solve one of the technical problems existing in the prior art. The grooving method for a TBC cell includes the following steps: sequentially preparing a first tunneling oxide layer, a P-Poly layer, and a first BSG layer on the back side of the cell substrate, and using a first laser treatment to remove the first BSG layer in a preset negative region; then performing a thermal oxidation treatment on the P-Poly layer to oxidize the P-Poly layer in the preset negative region into a second BSG layer, and using a second laser treatment to remove the second BSG layer and the first tunneling oxide layer in the preset negative region to obtain a cell sheet with grooves in the preset negative region. The present invention adopts a preparation method of laser patterning + thermal oxidation + laser patterning at the grooving position in the preset negative region, which will not damage the silicon substrate.

[0006] Another objective of the present invention is to provide an application of the grooving method for a TBC cell in the preparation of a TBC cell.

[0007] A third object of the present invention is to provide a method for manufacturing a TBC battery. The method for manufacturing a TBC battery includes the following steps: sequentially preparing a second tunneling oxide layer, an N-Poly layer, and a PSG layer in the grooved area of the cell wafer obtained by using the grooving method for the TBC battery, and annealing and crystallizing; removing the PSG layer in the preset positive electrode area and the PSG layer in the Gap area, then removing the N-poly layer, the second tunneling oxide layer, and the first BSG layer in the preset positive electrode area, and removing the PSG layer in the preset negative electrode area and removing the N-poly layer and the second tunneling oxide layer in the Gap area; preparing a passivation film on both sides of the cell wafer, and then performing metallization treatment on the cell wafer to manufacture a TBC battery. When the present invention removes the BSG layer, P-poly, and tunneling oxide layer in the preset negative electrode area during the manufacture of the TBC battery, it does not damage the silicon substrate, improves the absorption of long-wavelength light, increases the number of photo-generated carriers, increases the current, and ultimately improves the conversion efficiency of the battery.

[0008] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0009] In the first aspect, the present invention provides a grooving method for a TBC battery, and the grooving method for the TBC battery includes the following steps:

[0010] Sequentially prepare a first tunneling oxide layer, a P-Poly layer, and a first BSG layer on the back surface of the cell substrate, and use the first laser treatment to remove the first BSG layer in the preset negative electrode area;

[0011] After that, perform thermal oxidation treatment on the P-Poly layer to oxidize the P-Poly layer in the preset negative electrode area into a second BSG layer, and use the second laser treatment to remove the second BSG layer and the first tunneling oxide layer in the preset negative electrode area to obtain a cell wafer grooved in the preset negative electrode area.

[0012] In the present invention, for the grooving method for the TBC battery provided by the present invention, laser patterning + thermal oxidation + laser patterning is used for grooving at the grooved area in the preset negative electrode area (N area) of the TBC battery. First, use laser patterning to remove the first BSG layer at the grooved area, and then use the thermal oxidation method to oxidize the P-Poly layer so that the P-Poly layer in the preset negative electrode area is oxidized into a second BSG layer. This is because the absorption characteristics of silicon and silicon dioxide for laser are different, and laser etching cannot directly etch silicon, but can only etch the oxide of silicon. Therefore, the P-Poly layer is oxidized to form a BSG layer, and then laser patterning is used to remove the newly formed BSG layer and the remaining tunneling oxide layer.

[0013] Preferably, the first tunneling oxide layer, the P-Poly layer, and the first BSG layer are deposited by PECVD process;

[0014] Preferably, the thickness of the first tunneling oxide layer is 0.8 - 2.0 nm, for example, it can be 0.8 nm, 0.9 nm, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2.0 nm, etc.;

[0015] Preferably, the thickness of the P-Poly layer is 100 - 300 nm, for example, it can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc.;

[0016] Preferably, B2H6, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 300 - 400 °C, for example, it can be 300 °C, 350 °C, 400 °C, etc., and the deposition time is 10 - 40 min, for example, it can be 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, etc. The gas flow ratio of SiH4, H2, and B2H6 is 1:(9 - 12):(2 - 5). "9 - 12" can be, for example, 9, 10, 11, 12, etc., and "2 - 5" can be, for example, 2, 3, 4, 5, etc.; the gas flow of H2 is 2000 - 8000 sccm, for example, it can be 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, etc.

[0017] Preferably, the thickness of the first BSG layer is 30 - 100 nm, for example, it can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.;

[0018] Preferably, N2O, SiH4, B2H6 and H2 are introduced into the PECVD equipment to deposit the first BSG layer. The deposition temperature is 300 - 350 °C, such as 300 °C, 310 °C, 320 °C, 330 °C, 340 °C, 350 °C, etc. The deposition time is 70 - 90 min, such as 70 min, 75 min, 80 min, 85 min, 90 min, etc. The gas flow ratio of N2O and SiH4 is (5 - 9):1, such as 5:1, 6:1, 7:1, 8:1, 9:1, etc. The gas flow ratio of B2H6 and SiH4 is (4 - 10):1, such as 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc. The gas flow of H2 is 2000 - 8000 sccm, such as 2000 sccm, 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, 7000 sccm, 8000 sccm, etc.

[0019] Preferably, the power of the first laser treatment is 60 - 90%, such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. The depth is 30 - 80 nm, such as 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, etc. The width is 400 - 600 nm, such as 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, etc. The power of the second laser treatment is 60 - 90%, such as 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc. The depth is 50 - 200 nm, such as 50 nm, 100 nm, 150 nm, 200 nm, etc. The width is 400 - 600 nm, such as 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, etc.

[0020] Preferably, the temperature of the thermal oxidation treatment is 700 - 900 °C, such as 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, etc. The oxygen flow rate is 8 - 15 slm, such as 8 slm, 9 slm, 10 slm, 11 slm, 12 slm, 13 slm, 14 slm, 15 slm, etc. The pressure is 300 - 700 mbar, such as 300 mbar, 350 mbar, 400 mbar, 450 mbar, 500 mbar, 550 mbar, 600 mbar, 650 mbar, 700 mbar, etc. The time is 1 - 2 h, such as 1 h, 1.5 h, 2 h, etc.

[0021] Preferably, the N-type crystalline silicon substrate is preferably a battery substrate.

[0022] In a second aspect, the present invention provides an application of the described TBC cell grooving method in the preparation of TBC cells.

[0023] In a third aspect, the present invention provides a method for preparing a TBC cell, the method for preparing a TBC cell comprising the following steps:

[0024] Successively prepare a second tunneling oxide layer, an N-Poly layer, and a PSG layer in the grooved area and the Gap area of the cell wafer obtained by using the described TBC cell grooving method, and perform annealing crystallization;

[0025] Remove the PSG layer in the preset positive electrode area and the PSG layer in the Gap area, then remove the N-poly layer, the second tunneling oxide layer, and the first BSG layer in the preset positive electrode area, and remove the PSG layer in the preset negative electrode area and remove the N-poly layer and the second tunneling oxide layer in the Gap area;

[0026] Prepare a passivation film on both sides of the cell wafer, and then perform metallization treatment on the cell wafer to prepare a TBC cell, where the Gap area is the partition between the P area (preset positive electrode area) and the N area (preset negative electrode area).

[0027] In the present invention, the use of the preparation method provided by the present invention can improve the cell conversion efficiency of the TBC cell.

[0028] Preferably, the second tunneling oxide layer, the N-Poly layer, and the PSG layer are deposited by a PECVD process;

[0029] Preferably, the thickness of the second tunneling oxide layer is 0.8 - 2.0 nm, for example, it can be 0.8 nm, 0.9 nm, 1 nm, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, 1.9 nm, 2.0 nm, etc.;

[0030] Preferably, the thickness of the N-Poly layer is 100 - 300 nm, for example, it can be 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, etc.;

[0031] Preferably, PH3, SiH4 and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 400 - 500 °C, such as 400 °C, 450 °C, 500 °C, etc. The deposition time is 10 - 40 min, such as 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, etc. The flow rate ratio of SiH4, H2 and PH3 is 1:(1 - 3):(0.2 - 0.5). "1 - 3" can be 1, 2, 3, etc. "0.2 - 0.5" can be 0.2, 0.3, 0.4, 0.5, etc. The gas flow rate of H2 is 3000 - 6000 sccm, such as 3000 sccm, 4000 sccm, 5000 sccm, 6000 sccm, etc.;

[0032] Preferably, the thickness of the PSG layer is 30 - 100 nm, such as 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc.;

[0033] Preferably, SiH4, N2O, H2 and PH3 are introduced into the PECVD equipment to deposit the PSG layer. The deposition temperature is 400 - 500 °C, such as 400 °C, 410 °C, 420 °C, 430 °C, 440 °C, 450 °C, 460 °C, 470 °C, 480 °C, 490 °C, 500 °C, etc. The deposition time is 70 - 90 min, such as 70 min, 75 min, 80 min, 85 min, 90 min, etc. The gas flow rate ratio of N2O and SiH4 is (4 - 6):1, such as 4:1, 5:1, 6:1, etc. The gas flow rate ratio of PH3 and SiH4 is (1 - 3):1, such as 1:1, 2:1, 3:1, etc. The gas flow rate of H2 is 3000 - 6000 sccm, such as 3000 sccm, 3500 sccm, 4000 sccm, 4500 sccm, 5000 sccm, 5500 sccm, 6000 sccm, etc.

[0034] Preferably, the temperature of the annealing is 800 - 950 °C, such as 800 °C, 850 °C, 900 °C, etc. The annealing time is 0.5 - 2 h, such as 0.5 h, 1 h, 1.5 h, 2 h, etc.

[0035] Preferably, the PSG layer in the preset positive electrode region and the PSG layer in the Gap region are removed by the third laser treatment;

[0036] Preferably, the power of the third laser treatment is 60-90%, for example, it can be 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc., and the depth is 30-80 nm, for example, it can be 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, etc.

[0037] Preferably, a cleaning and texturing process is used to remove the N-poly layer, the second tunneling oxide layer, the first BSG layer in the preset positive electrode region, the PSG layer in the preset negative electrode region, and the N-poly layer and the second tunneling oxide layer in the Gap region;

[0038] In the present invention, a cleaning and texturing process is adopted to retain the N-PolySi layer on the back N region of the silicon substrate, remove the N-PolySi layer in other regions, and the BSG layer on the back of the silicon substrate.

[0039] Preferably, the reagent used for the cleaning and texturing is a NaOH solution with a concentration of 0.4% ± 0.1%;

[0040] Preferably, preparing the passivation film includes preparing an alumina layer and a silicon nitride layer.

[0041] Furthermore, the method for preparing the TBC battery includes the following steps:

[0042] Step 1: Select an N-type crystalline silicon substrate and perform a double-sided polishing process step;

[0043] Step 2: Deposit a first tunneling oxide layer, a P-Poly layer, and a first BSG layer on the cell wafer processed in Step 1 by PECVD;

[0044] Step 3: Perform a first laser patterning on the cell wafer processed in Step 2 to remove the first BSG layer in the preset negative electrode region (N region) on the back of the cell wafer;

[0045] Step 4: Perform a backside thermal oxidation on the cell wafer processed in Step 3 to oxidize the P-poly layer exposed on the back N region into a second BSG layer;

[0046] Step 5: Perform a second laser patterning on the cell wafer processed in Step 4 to remove the newly formed second BSG layer in the N region and the remaining first tunneling oxide layer, obtaining a cell wafer with slots in the preset negative electrode region;

[0047] Step 6: Deposit a second tunneling oxide layer, an N-Poly layer, and a PSG layer on the slotted region and the Gap region of the cell wafer by PECVD in sequence;

[0048] Step 7: Anneal and crystallize;

[0049] Step 8: Perform the third laser patterning on the solar cell processed in Step 7 to remove the PSG layer in the preset positive electrode region and the PSG layer in the Gap region;

[0050] Step 9: Clean and texture the solar cell processed in Step 8 to remove the N-poly layer, the second tunneling oxide layer, and the first BSG layer in the preset positive electrode region, remove the PSG layer in the preset negative electrode region, and remove the N-poly layer and the second tunneling oxide layer in the Gap region;

[0051] Step 10: Deposit alumina layers on both sides of the solar cell processed in Step 9, deposit SiNx films on the front and back, and then metallize to fabricate the solar cell.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] In the TBC solar cell grooving method provided by the present invention, laser patterning + thermal oxidation + laser patterning is used for grooving at the grooving position in the preset negative electrode region (N region) of the TBC solar cell. First, the first BSG layer at the grooving position is removed by laser patterning, and then the P-Poly layer is oxidized by thermal oxidation to oxidize the P-Poly layer in the preset negative electrode region into the second BSG layer. This is because the absorption characteristics of silicon and silicon dioxide for laser are different, and laser etching cannot directly etch silicon but can only etch the oxide of silicon. Therefore, the P-Poly layer is oxidized to form the BSG layer, and then laser patterning is used to remove the newly formed BSG layer and the remaining tunneling oxide layer.

[0054] When the TBC solar cell provided by the present invention removes the BSG layer, P-poly, and tunneling oxide layer in the N region by grooving, the silicon substrate is not damaged, the absorption of long-wavelength light is improved, the number of photo-generated carriers is increased, the current is increased, and finally the conversion efficiency of the solar cell is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0056] Figure 1 It is a schematic structural diagram of the present invention with a first tunneling oxide layer, a P-Poly layer, and a first BSG layer deposited on the back of the solar cell substrate;

[0057] Figure 2 It is a schematic structural diagram of the solar cell after the first laser patterning;

[0058] Figure 3Schematic diagram of a structure where a second tunneling oxide layer, an N-Poly layer, and a PSG layer are deposited in a preset negative electrode region of a cell wafer;

[0059] Figure 4 Schematic diagram of the cell wafer structure after the third laser patterning;

[0060] Figure 5 Schematic diagram of the cell wafer structure after cleaning and texturing;

[0061] Figure 6 Schematic diagram of the structure of a completed TBC cell.

[0062] Icons: 10 - First tunneling oxide layer; 20 - P-Poly layer; 30 - First BSG layer; 40 - Second tunneling oxide layer; 50 - N-Poly layer; 60 - PSG layer; 70 - N-type crystalline silicon substrate; 80 - Aluminum oxide layer; 90 - Silicon nitride layer; 100 - Silicon oxide layer; 110 - P-region electrode; 120 - N-region electrode; 130 - N++ layer. Detailed implementation manners

[0063] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meanings and scopes of the terms should be clear. However, in any case of potential ambiguity, the definitions provided herein shall prevail over any dictionary or extrinsic definition. In this application, unless otherwise specified, the use of "or" means "and / or". Additionally, the use of the term "comprising" and other forms is non-restrictive.

[0064] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0065] The present invention provides a method for preparing a TBC cell, comprising the following steps:

[0066] Step 1: Select an N-type crystalline silicon substrate 70 and perform a double-sided polishing process step;

[0067] Step 2: Deposit a first tunneling oxide layer 10, a P-Poly layer 20, and a first BSG layer 30 on the cell wafer processed in Step 1 by PECVD. The structure of the cell wafer is as Figure 1 shown.

[0068] Step 3: Perform the first laser patterning on the cell wafer processed in Step 2 to remove the first BSG layer 30 in the preset negative electrode region (N region) on the back of the cell wafer. The structure of the cell wafer after the first laser patterning is asFigure 2 as shown

[0069] Step 4: Perform backside thermal oxidation on the solar cell processed in Step 3 to oxidize the P-Poly layer 20 exposed in the backside N region into the second BSG layer;

[0070] Step 5: Perform a second laser patterning on the solar cell processed in Step 4 to remove the newly formed second BSG layer in the N region and the remaining first tunneling oxide layer 10, obtaining a solar cell with grooves opened in the preset negative electrode region;

[0071] Step 6: Sequentially deposit a second tunneling oxide layer 40, an N-Poly layer 50, and a PSG layer 60 on the grooved region and the Gap region of the solar cell by PECVD. The structure of the solar cell is as Figure 3 shown, where the PSG layer 60 and the N++ layer 130 on the front side of the solar cell are front side overcoats.

[0072] Step 7: Anneal and crystallize;

[0073] Step 8: Perform a third laser patterning on the solar cell processed in Step 7 to remove the PSG layer 60 in the preset positive electrode region and the PSG layer 60 in the Gap region. The structure of the solar cell after the third laser patterning is as Figure 4 shown;

[0074] Step 9: Perform cleaning and texturing on the solar cell processed in Step 8 to remove the N-Poly layer 50, the second tunneling oxide layer 40, and the first BSG layer 30 in the preset positive electrode region, and remove the PSG layer 60 in the preset negative electrode region and remove the N-Poly layer 50 and the second tunneling oxide layer 40 in the Gap region. The structure of the solar cell after cleaning and texturing is as Figure 5 shown;

[0075] Step 10: Perform double-sided preparation of an alumina layer 80 and deposit silicon nitride layers 90 (SiNx films) on the front and back sides of the solar cell processed in Step 9, and then metallize to fabricate a solar cell. The structure of the solar cell is as Figure 6 shown. Among them, the paste is formed into an N-region electrode 120 and a P-region electrode 110 by screen printing. The silicon oxide layer 100 is deposited when depositing silicon nitride on the front side and is generated by the ionization of SiH4 and N2O.

[0076] The present invention will be further described below through embodiments. Unless otherwise specified, the materials in the embodiments are prepared according to existing methods or directly purchased from the market.

[0077] Embodiment 1

[0078] This embodiment provides a method for grooving a TBC solar cell, including the following steps:

[0079] Step 1: Select an N-type crystalline silicon substrate and perform a double-sided polishing process step;

[0080] Step 2: Deposit a tunneling oxide layer, a P-Poly layer, and a BSG layer on the cell wafer processed in Step 1 through the PECVD process;

[0081] Among them, the thickness of the tunneling oxide layer is 0.8 nm. During the Poly deposition process, B2H6 gas is introduced to achieve in-situ doping, and the thickness of the P-Poly layer is 300 nm;

[0082] Among them, B2H6, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 300 °C, the deposition time is 40 min, and the gas flow ratio of SiH4, H2, and B2H6 is 1:9:5, and the gas flow of H2 is 2000 sccm;

[0083] Among them, the thickness of the BSG layer is 30 nm. N2O, SiH4, B2H6, and H2 are introduced into the PECVD equipment to deposit the BSG layer. The deposition temperature is 300 °C, the deposition time is 70 min, the gas flow ratio of N2O and SiH4 is 5:1, the gas flow ratio of B2H6 and SiH4 is 10:1, and the gas flow of H2 is 2000 sccm.

[0084] Step 3: Perform the first laser patterning on the cell wafer processed in Step 2 to remove the BSG layer in the preset negative electrode area (N area) on the back of the cell wafer;

[0085] Among them, the power of the first laser treatment is 60%, the depth is 30 nm, and the width is 400 nm.

[0086] Step 4: Perform backside thermal oxidation on the cell wafer processed in Step 3 to oxidize the P-poly layer exposed in the back N area into a BSG layer;

[0087] Among them, the temperature of the thermal oxidation treatment is 700 °C, the oxygen flow rate is 15 slm, the pressure is 700 mbar, and the time is 1 h.

[0088] Step 5: Perform the second laser patterning on the cell wafer processed in Step 4 to remove the newly formed BSG layer and the remaining tunneling oxide layer in the N area, and obtain a cell wafer with slots in the preset negative electrode area;

[0089] Among them, the power of the second laser treatment is 60%, the depth is 50 nm, and the width is 400 nm.

[0090] Example 2

[0091] This example provides a method for slotting a TBC cell, including the following steps:

[0092] Step 1: Select an N-type crystalline silicon substrate and perform a double-sided polishing process step;

[0093] Step 2: Deposit a tunneling oxide layer, a P-Poly layer, and a BSG layer on the cell processed in Step 1 by PECVD process;

[0094] Among them, the thickness of the tunneling oxide layer is 2.0 nm. During the Poly deposition process, B2H6 gas is introduced to achieve in-situ doping, and the thickness of the P-Poly layer is 100 nm;

[0095] Among them, B2H6, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 400 °C, the deposition time is 10 min, and the gas flow ratio of SiH4, H2, and B2H6 is 1:12:2. The gas flow of H2 is 8000 sccm;

[0096] Among them, the thickness of the BSG layer is 100 nm. N2O, SiH4, B2H6, and H2 are introduced into the PECVD equipment to deposit the BSG layer. The deposition temperature is 350 °C, the deposition time is 90 min, the gas flow ratio of N2O and SiH4 is 9:1, the gas flow ratio of B2H6 and SiH4 is 4:1, and the gas flow of H2 is 8000 sccm.

[0097] Step 3: Perform the first laser patterning on the cell processed in Step 2 to remove the BSG layer in the preset negative electrode area (N area) on the back of the cell;

[0098] Among them, the power of the first laser treatment is 90%, the depth is 80 nm, and the width is 600 nm.

[0099] Step 4: Perform backside thermal oxidation on the cell processed in Step 3 to oxidize the P-poly layer exposed in the back N area into a BSG layer;

[0100] Among them, the thermal oxidation treatment temperature is 900 °C, the oxygen flow rate is 8 slm, the pressure is 300 mbar, and the time is 2 h.

[0101] Step 5: Perform the second laser patterning on the cell processed in Step 4 to remove the newly formed BSG layer and the remaining tunneling oxide layer in the N area, and obtain a cell with grooves in the preset negative electrode area;

[0102] Among them, the power of the second laser treatment is 90%, the depth is 200 nm, and the width is 600 nm.

[0103] Example 3

[0104] This embodiment provides a method for grooving a TBC battery, including the following steps:

[0105] Step 1: Select an N-type crystalline silicon substrate and perform a double-sided polishing process step;

[0106] Step 2: Deposit a tunneling oxide layer, a P-Poly layer, and a BSG layer on the cell wafer processed in Step 1 through the PECVD process;

[0107] Among them, the thickness of the tunneling oxide layer is 1.4 nm. During the Poly deposition process, B2H6 gas is introduced to achieve in-situ doping, and the thickness of the P-Poly layer is 200 nm;

[0108] Among them, B2H6, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 350 °C, the deposition time is 25 min, and the gas flow ratio of SiH4, H2, and B2H6 is 1:11:4. The gas flow of H2 is 5000 sccm;

[0109] Among them, the thickness of the BSG layer is 65 nm. N2O, SiH4, B2H6, and H2 are introduced into the PECVD equipment to deposit the BSG layer. The deposition temperature is 325 °C, the deposition time is 80 min, the gas flow ratio of N2O and SiH4 is 7:1, the gas flow ratio of B2H6 and SiH4 is 7:1, and the gas flow of H2 is 5000 sccm.

[0110] Step 3: Perform the first laser patterning on the cell wafer processed in Step 2 to remove the BSG layer in the preset negative electrode region (N region) on the back of the cell wafer;

[0111] Among them, the power of the first laser treatment is 75%, the depth is 55 nm, and the width is 500 nm.

[0112] Step 4: Perform backside thermal oxidation on the cell wafer processed in Step 3 to oxidize the P-poly layer exposed in the backside N region into a BSG layer;

[0113] Among them, the temperature of the thermal oxidation treatment is 800 °C, the oxygen flow rate is 12 slm, the pressure is 500 mbar, and the time is 1.5 h.

[0114] Step 5: Perform the second laser patterning on the cell wafer processed in Step 4 to remove the newly formed BSG layer and the remaining tunneling oxide layer in the N region, obtaining a cell wafer with grooves in the preset negative electrode region;

[0115] Among them, the power of the second laser treatment is 75%, the depth is 125 nm, and the width is 500 nm.

[0116] Example 4

[0117] This embodiment provides a method for preparing a TBC battery, comprising the following steps:

[0118] Step 1: Using the grooved cell wafer prepared in Example 3, sequentially deposit a tunneling oxide layer, an N-Poly layer, and a PSG layer on the grooved area and the Gap area of the cell wafer through PECVD;

[0119] Among them, the thickness of the tunneling oxide layer is 0.8 nm. During the Poly deposition process, PH3 gas is introduced to achieve in-situ doping, and the thickness of the N-Poly layer is 300 nm;

[0120] Among them, PH3, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 400 °C, the deposition time is 40 min, the gas flow ratio of SiH4, H2, and PH3 is 1:1:0.5, and the gas flow of H2 is 3000 sccm;

[0121] Among them, the thickness of the PSG layer is 30 nm. SiH4, N2O, H2, and PH3 are introduced into the PECVD equipment to deposit the PSG layer. The deposition temperature is 400 °C, the deposition time is 70 min, the gas flow ratio of N2O and SiH4 is 4:1, the gas flow ratio of PH3 and SiH4 is 3:1, and the gas flow of H2 is 3000 sccm.

[0122] Step 2: Anneal and crystallize. The annealing temperature is 800 °C, and the annealing time is 2 h;

[0123] Step 3: Perform third laser patterning on the cell wafer processed in Step 2 to remove the PSG layer in the preset positive electrode area and the PSG layer in the Gap area;

[0124] Among them, the power of the third laser treatment is 60%, and the depth is 30 nm.

[0125] Step 4: Clean and texture the cell wafer processed in Step 3 to remove the N-poly layer, the tunneling oxide layer, and the BSG layer in the preset positive electrode area, and remove the PSG layer in the preset negative electrode area and remove the N-poly layer and the tunneling oxide layer in the Gap area;

[0126] Among them, the reagent used for cleaning and texturing is a NaOH solution with a concentration of 0.4% ± 0.1%.

[0127] Step 5: Prepare an alumina layer on both sides of the cell wafer processed in Step 4 and deposit SiNx films on the front and back, and then metallize to form a battery.

[0128] Example 5

[0129] This embodiment provides a method for preparing a TBC battery, comprising the following steps:

[0130] Step 1: Using the grooved cell wafer prepared in Example 3, sequentially deposit a tunneling oxide layer, an N-Poly layer, and a PSG layer on the grooved area and the Gap area of the cell wafer by PECVD;

[0131] Among them, the thickness of the tunneling oxide layer is 2.0 nm. PH3 gas is introduced during the Poly deposition process to achieve in-situ doping, and the thickness of the N-Poly layer is 100 nm;

[0132] Among them, PH3, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 500 °C, the deposition time is 10 min, the gas flow ratio of SiH4, H2, and PH3 is 1:3:0.2, and the gas flow of H2 is 6000 sccm;

[0133] Among them, the thickness of the PSG layer is 100 nm. SiH4, N2O, H2, and PH3 are introduced into the PECVD equipment to deposit the PSG layer. The deposition temperature is 500 °C, the deposition time is 90 min, the gas flow ratio of N2O and SiH4 is 6:1, the gas flow ratio of PH3 and SiH4 is 1:1, and the gas flow of H2 is 6000 sccm.

[0134] Step 2: Anneal and crystallize, the annealing temperature is 950 °C, and the annealing time is 0.5 h;

[0135] Step 3: Perform third laser patterning on the cell wafer processed in Step 2 to remove the PSG layer in the preset positive electrode area and the PSG layer in the Gap area;

[0136] Among them, the power of the third laser treatment is 90%, and the depth is 80 nm.

[0137] Step 4: Clean and texture the cell wafer processed in Step 3 to remove the N-poly layer, the tunneling oxide layer, and the BSG layer in the preset positive electrode area, the PSG layer in the preset negative electrode area, and the N-poly layer and the tunneling oxide layer in the Gap area;

[0138] Among them, the reagent used for cleaning and texturing is a NaOH solution with a concentration of 0.4% ± 0.1%.

[0139] Step 5: Prepare an alumina layer on both sides of the cell wafer processed in Step 4 and deposit SiNx films on the front and back, and then metallize to make a battery.

[0140] Examples 6 - 8

[0141] This embodiment provides a method for preparing a TBC battery, comprising the following steps:

[0142] Step 1: Respectively use the grooved cell wafers prepared in Examples 1-3, and sequentially deposit a tunneling oxide layer, an N-Poly layer, and a PSG layer on the grooved area and the Gap area of the cell wafer by PECVD;

[0143] Among them, the thickness of the tunneling oxide layer is 1.4 nm, PH3 gas is introduced during the Poly deposition process to achieve in-situ doping, and the thickness of the N-Poly layer is 200 nm;

[0144] Among them, PH3, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer, the deposition temperature is 450 °C, the deposition time is 25 min, the gas flow ratio of SiH4, H2, and PH3 is 1:2:0.3, and the gas flow of H2 is 4500 sccm;

[0145] Among them, the thickness of the PSG layer is 65 nm, SiH4, N2O, H2, and PH3 are introduced into the PECVD equipment to deposit the PSG layer, the deposition temperature is 450 °C, the deposition time is 80 min, the gas flow ratio of N2O and SiH4 is 5:1, the gas flow ratio of PH3 and SiH4 is 2:1, and the gas flow of H2 is 4500 sccm.

[0146] Step 2: Anneal and crystallize, the annealing temperature is 900 °C, and the annealing time is 1.5 h;

[0147] Step 3: Perform third laser patterning on the cell wafer processed in Step 2 to remove the PSG layer in the preset positive electrode area and the PSG layer in the Gap area;

[0148] Among them, the power of the third laser treatment is 75%, and the depth is 55 nm.

[0149] Step 4: Clean and texture the cell wafer processed in Step 3 to remove the N-poly layer, the tunneling oxide layer, and the BSG layer in the preset positive electrode area, and remove the PSG layer in the preset negative electrode area, and remove the N-poly layer and the tunneling oxide layer in the Gap area;

[0150] Among them, the reagent used for cleaning and texturing is a NaOH solution, and the concentration is 0.4% ± 0.1%.

[0151] Step 5: Perform double-sided preparation of an alumina layer and deposit SiNx films on the front and back surfaces on the cell wafer processed in Step 4, and then metallize to make a battery to obtain the TBC batteries of Examples 6-8.

[0152] Comparative Example 1

[0153] This comparative example provides a method for grooving a TBC cell. The difference from Example 3 is that in Step 4, an alkaline solution polishing method is used to remove the P-poly and tunneling oxide layers. The alkaline solution used is NaOH.

[0154] Comparative Example 2

[0155] This comparative example provides a method for preparing a TBC cell. The difference from Example 8 is that:

[0156] In Step 1, the grooved cell wafer prepared in Comparative Example 1 is used;

[0157] The rest is the same as Example 8.

[0158] Test example:

[0159] Test samples: The TBC cells prepared in Examples 4 - 8 and the TBC cell in Comparative Example 2 are used.

[0160] Test method: The samples are tested using a Halm system. The test results are shown in Table 1.

[0161] Table 1

[0162] sample battery conversion efficiency Example 4 26.88％ Example 5 26.85％ Example 6 26.82％ Example 7 26.80％ Example 8 26.95％ Comparative Example 2 26.75％

[0163] As can be seen from Table 1, compared with Comparative Example 2, the TBC cells prepared by the preparation method provided in the embodiments of the present invention have a higher conversion efficiency.

[0164] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A grooving method for a TBC battery, characterized in that, The TBC cell grooving method includes the following steps: A first tunneling oxide layer, a P-Poly layer, and a first BSG layer are sequentially prepared on the back surface of the cell substrate, and the first BSG layer in the preset negative electrode region is removed by a first laser treatment; Thereafter, thermal oxidation treatment is performed on the P-Poly layer to oxidize the P-Poly layer in the preset negative electrode region into a second BSG layer, and the second BSG layer and the first tunneling oxide layer in the preset negative electrode region are removed by a second laser treatment to obtain a cell wafer with grooves in the preset negative electrode region.

2. The TBC battery grooving method according to claim 1, wherein, The first tunneling oxide layer, the P-Poly layer, and the first BSG layer are deposited by a PECVD process.

3. The TBC cell grooving method according to claim 2, wherein The thickness of the first tunneling oxide layer is 0.8 - 2.0 nm.

4. The grooving method of the TBC battery according to claim 2, wherein The thickness of the P-Poly layer is 100 - 300 nm.

5. The TBC battery grooving method according to claim 2, wherein B2H6, SiH4, and H2 are introduced into the PECVD equipment to deposit the P-Poly layer. The deposition temperature is 300 - 400 °C, the deposition time is 10 - 40 min, the gas flow ratio of SiH4, H2, and B2H6 is 1:(9 - 12):(2 - 5), and the gas flow of H2 is 2000 - 8000 sccm.

6. The grooving method of the TBC cell according to claim 2, characterized in that, The thickness of the first BSG layer is 30 - 100 nm.

7. The TBC battery grooving method according to claim 2, characterized in that, N2O, SiH4, B2H6, and H2 are introduced into the PECVD equipment to deposit the first BSG layer. The deposition temperature is 300 - 350 °C, the deposition time is 70 - 90 min, the gas flow ratio of N2O and SiH4 is (5 - 9):1, the gas flow ratio of B2H6 and SiH4 is (4 - 10):1, and the gas flow of H2 is 2000 - 8000 sccm.

8. The TBC battery grooving method according to claim 1, wherein, The power of the first laser treatment is 60 - 90%, the depth is 30 - 80 nm, and the width is 400 - 600 nm. The power of the second laser treatment is 60 - 90%, the depth is 50 - 200 nm, and the width is 400 - 600 nm.

9. The TBC battery grooving method according to claim 1, wherein, The temperature of the thermal oxidation treatment is 700 - 900 °C, the oxygen flow rate is 8 - 15 slm, the pressure is 300 - 700 mbar, and the time is 1 - 2 h.

10. The application of the TBC cell grooving method according to any one of claims 1 - 9 in the preparation of TBC cells.

11. A method for preparing a TBC battery, characterized in that, The TBC cell preparation method includes the following steps: A second tunneling oxide layer, an N-Poly layer, and a PSG layer are sequentially prepared in the grooved area and the Gap area of the cell wafer obtained by using the TBC cell grooving method according to any one of claims 1 - 9, and annealing crystallization is performed; The PSG layer in the preset positive electrode region and the PSG layer in the Gap area are removed, and then the N-poly layer, the second tunneling oxide layer, and the first BSG layer in the preset positive electrode region are removed, and the PSG layer in the preset negative electrode region and the N-poly layer and the second tunneling oxide layer in the Gap area are removed; A passivation film is prepared on both sides of the cell wafer, and then the cell wafer is metallized to prepare a TBC cell; Among them, the Gap area is the partition between the preset positive electrode region and the preset negative electrode region.

12. The method for preparing a TBC battery according to claim 11, wherein, The second tunneling oxide layer, the N-Poly layer and the PSG layer are deposited by PECVD process.

13. The method for preparing a TBC battery according to claim 11, characterized in that, The thickness of the second tunneling oxide layer is 0.8 - 2.0 nm.

14. The method for preparing a TBC battery according to claim 11, wherein, The thickness of the N-Poly layer is 100 - 300 nm.

15. The method for preparing a TBC battery according to claim 11, wherein, PH3, SiH4 and H2 are introduced into the PECVD equipment to deposit the N-Poly layer. The deposition temperature is 400 - 500 °C, the deposition time is 10 - 40 min, the gas flow ratio of SiH4, H2 and PH3 is 1:(1 - 3):(0.2 - 0.5), and the gas flow of H2 is 3000 - 6000 sccm.

16. The method for preparing a TBC battery according to claim 11, wherein The thickness of the PSG layer is 30 - 100 nm.

17. The method for preparing a TBC battery according to claim 11, wherein SiH4, N2O, H2 and PH3 are introduced into the PECVD equipment to deposit the PSG layer. The deposition temperature is 400 - 500 °C, the deposition time is 70 - 90 min, the gas flow ratio of N2O and SiH4 is (4 - 6):1, the gas flow ratio of PH3 and SiH4 is (1 - 3):1, and the gas flow of H2 is 3000 - 6000 sccm.

18. The method for preparing a TBC battery according to claim 11, wherein, The annealing temperature is 800 - 950 °C, and the annealing time is 0.5 - 2 h.

19. The method for preparing a TBC battery according to claim 11, wherein The PSG layer in the preset positive electrode region and the PSG layer in the Gap region are removed by the third laser treatment.

20. The method for preparing a TBC battery according to claim 19, wherein, The power of the third laser treatment is 60 - 90%, and the depth is 30 - 80 nm.

21. The method for preparing a TBC battery according to claim 11, characterized in that, The N-poly layer, the second tunneling oxide layer, the first BSG layer in the preset positive electrode region are removed by the cleaning and texturing process, and the PSG layer in the preset negative electrode region and the N-poly layer and the second tunneling oxide layer in the Gap region are removed.

22. The manufacturing method of the TBC battery according to claim 21, characterized in that, The reagent used for the cleaning and texturing is NaOH solution with a concentration of 0.4% ± 0.1%.

23. The method for preparing a TBC battery according to claim 11, wherein Preparing the passivation film includes preparing an alumina layer and a silicon nitride layer.

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