A method for manufacturing a back contact heterojunction solar cell with low laser damage

Abstract

The application provides a low-laser-damage back contact heterojunction solar cell manufacturing method, which comprises the following steps: A, a first conductive type film layer is arranged on a part of a first main surface of a semiconductor substrate to form a first conductive region of the first conductive type, and the specific method of the step A is as follows: a1, a first conductive type film layer, a first insulating layer and a laser absorption sacrificial layer are sequentially formed on the first main surface of the semiconductor substrate; a2, the laser absorption sacrificial layer in a region other than the first conductive region is removed by laser etching; and a3, the first insulating layer and the first conductive type film layer not covered by the laser absorption sacrificial layer are removed by chemical etching to form the first conductive region with the insulating film layer attached to the surface. The application aims to provide a low-laser-damage back contact heterojunction solar cell manufacturing method, which can reduce laser damage, reduce the influence of thermal decay and improve photoelectric conversion efficiency.

Description

Technical Field

[0001] This invention relates to a method for manufacturing a back-contact heterojunction solar cell with low laser damage. Background Technology

[0002] Following SunPower's pioneering launch of mass-produced back-contact cells and modules internationally, Panasonic's heterojunction division, leveraging the unique advantages of back-contact technology in power generation efficiency and appearance, began investing in the development of low-temperature back-contact technology in heterojunctions in 2014. However, to date, the back-contact technology process is complex, and frequent contact with the cell surface damages surface passivation, hindering cost reduction and improved mass production efficiency. It is estimated that each additional printing process lowers the absolute efficiency of the cell by 0.2%, and the technology for opening the back electrode primarily relies on ink printing and chemical etching, limiting the potential for cost reduction. The key to the mass production and widespread adoption of back-contact technology is reducing production steps and minimizing efficiency loss caused by mechanical contact, a goal that can be achieved through the extensive application of laser-guided openings. However, since heterojunctions, primarily based on amorphous silicon, are low-temperature processes (below 200 degrees Celsius), the grown film is highly sensitive to the thermal effects of lasers. Therefore, reducing the thermal degradation effect caused by laser-guided openings is a crucial research and development challenge for back-contact technology. Summary of the Invention

[0003] The purpose of this invention is to provide a method for manufacturing back-contact heterojunction solar cells with low laser damage, which can reduce laser damage, reduce the impact of thermal decay, and improve photoelectric conversion efficiency.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A method for manufacturing a back-contact heterojunction solar cell with low laser damage includes step A, which involves depositing a first conductive film layer with a surface-covered insulating film layer on a portion of a first main surface of a semiconductor substrate to form a first conductive region of the first conductive type.

[0006] The specific method for step A is as follows:

[0007] a1, a first conductive film layer, a first insulating layer and a laser absorption sacrificial layer are sequentially formed on the first main surface of the semiconductor substrate;

[0008] a2, laser etching is used to remove the laser absorption sacrificial layer in areas other than the first conductive region;

[0009] a3, using chemical etching to remove the first insulating layer and the first conductive film layer that are not covered by the laser absorption sacrificial layer, to form a first conductive area with the insulating film layer attached to the surface.

[0010] Compared with the prior art, the advantages of the present invention are as follows:

[0011] (1) By setting a laser absorption sacrificial layer, not only can the laser be absorbed to reduce the damage of the laser to the first conductive region film layer, but it can also be used as an etching mask to remove the first conductive film layer outside the first conductive region and protect the first insulating layer of the first conductive region.

[0012] (2) The second conductive film covering the first conductive area has only a laser opening as minimal as possible, which ensures the conductive contact between the first conductive area and the electrode, reduces the number of processes, controls laser damage, and improves photoelectric conversion efficiency.

[0013] (3) The N-type conductive thin film layer is made of oxygen-doped or non-oxygen-doped microcrystalline layer. The carrier mobility and effective doping of the N-type conductive microcrystalline layer are significantly different from those of the N-type amorphous film layer, which can greatly improve the lateral collection capability of the N-type collecting electrode and make the aperture ratio of the N-type electrode decrease significantly. Attached Figure Description

[0014] Figure 1 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0015] Figure 2 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0016] Figure 3 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0017] Figure 4 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0018] Figure 5 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0019] Figure 6 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0020] Figure 7 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0021] Figure 8 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0022] Figure 9 This is a cross-sectional schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0023] Figure 10 This is a partial schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0024] Figure 11 This is a partial schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0025] Figure 12 This is a partial schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0026] Figure 13 This is a partial schematic diagram of a manufacturing process of the solar cell unit of the present invention.

[0027] Figure 14 This is a schematic diagram of the structure of the first main surface of an embodiment of the solar cell unit of the present invention. The metal grid electrodes 42 and 47 have an interdigitated structure. Figure 9 This is a schematic diagram of the BB section in this figure.

[0028] Figure 15 This is a schematic diagram of the structure of the first main surface of an embodiment of the solar cell unit of the present invention. The metal grid electrode is designed in a half-cell symmetrical manner. After the cell unit is manufactured, it is divided into two halves by laser cutting to form a half-cell module.

[0029] Figure 16 This is a simplified structural diagram of another embodiment of the solar cell unit of the present invention. Detailed Implementation

[0030] A method for manufacturing a back-contact heterojunction solar cell with low laser damage, comprising the following steps:

[0031] Step A: A first conductive film layer with an insulating film layer on its surface is formed on a portion of the first main surface of the semiconductor substrate to form a first conductive region of the first conductive type;

[0032] Step B: A second conductive film layer is formed on the first main surface of the semiconductor substrate after the treatment in step A;

[0033] Step C: Remove a portion of the second conductive film layer covering the area inside the first conductive region using laser discontinuous etching or laser linear etching.

[0034] Step D involves removing the insulating film layer that does not cover the second conductive film layer using chemical etching.

[0035] The specific method for step A is as follows:

[0036] a1, a first conductive film layer, a first insulating layer and a laser absorption sacrificial layer are sequentially formed on the first main surface of the semiconductor substrate;

[0037] a2, laser etching is used to remove the laser absorption sacrificial layer in areas other than the first conductive region;

[0038] a3, using chemical etching to remove the first insulating layer and the first conductive film layer that are not covered by the laser absorption sacrificial layer, to form a first conductive area with the insulating film layer attached to the surface.

[0039] The specific process for the laser absorption sacrificial layer is to deposit an amorphous silicon thin film on a first insulating layer as a substrate.

[0040] The first conductive film layer is an N-type conductive film layer, and the deposition process of the first conductive film layer includes forming an oxygen-doped or non-oxygen-doped microcrystalline layer; the second conductive film layer is a P-type conductive film layer.

[0041] The film-forming rate of the oxygen-doped microcrystalline layer is controlled at 0.2-2 Å / s, the film thickness is 40-200 Å, and the optical refractive index after film formation is between 2.2 and 3.1.

[0042] The first conductive film layer is composed of a first passivation layer and a first semiconductor layer formed sequentially from bottom to top on the first main surface of the semiconductor substrate; the second conductive film layer is composed of a second passivation layer and a second semiconductor layer formed sequentially from bottom to top on the first main surface of the semiconductor substrate.

[0043] Step B further includes sequentially depositing a third passivation film layer and an optical antireflection layer on the second main surface of the semiconductor substrate.

[0044] The specific method of step C is to use laser discontinuous etching to remove part of the second conductive film layer covering the middle region of the first conductive region, so that the second conductive film layer covering the first conductive region forms a hole array that exposes the insulating film layer. Adjacent holes do not contact each other, and the hole array consists of one or more rows of holes.

[0045] In step C, the laser is pulsed with a pulse width of less than 20 nanoseconds; the laser spot formed on the back of the silicon wafer is circular, elliptical, or rectangular; the laser is spatially shaped into a flat-top laser.

[0046] The method for manufacturing a back-contact heterojunction solar cell further includes the following steps.

[0047] Step E: After the processing in step D, a conductive layer is formed on the surface of the first conductive region and the second conductive region.

[0048] Step F: An anti-deposition layer is formed on the conductive layer by printing to create the electrode pattern to be deposited;

[0049] Step G: An electrode is formed on the surface of the region of the conductive layer that is not covered by the anti-deposition layer;

[0050] Step H involves creating grooves in the anti-deposited layer and the conductive layer area it covers using laser etching or a combination of laser etching and chemical etching; the grooves form a separating insulation between the first conductive area and the second conductive area.

[0051] Step I involves using chemical etching to remove the anti-deposition layer and the conductive layer covering it.

[0052] The specific method of step E is to sequentially fabricate a transparent conductive film and a metal conductive film on the first main surface of the semiconductor substrate after the treatment in step D to form a conductive layer.

[0053] The transparent conductive film is an indium oxide thin film doped with hydrogen, tin oxide, titanium oxide, zinc oxide, or gallium oxide; the mass percentage of the doped hydrogen, tin oxide, titanium oxide, zinc oxide, or gallium oxide is 0-10%.

[0054] The process for preparing the hydrogen-doped indium oxide thin film involves using pure indium oxide as the target material, then introducing hydrogen or water vapor into the process gas, and forming the hydrogen-doped indium oxide thin film through physical vapor deposition.

[0055] The specific method of step F is to print anti-electroplating ink on the conductive layer obtained by step E.

[0056] The specific method of step G is to use electroplating to fabricate the first conductive region electrode and the second conductive region electrode on the first conductive region and the second conductive region after the treatment in step C.

[0057] The specific process of step G is to form an electroplated copper grid electrode by means of immersion or horizontal brush contact, and to form a protective tin layer of 100 nanometers to 5 micrometers on the copper grid electrode by means of chemical tin covering or electroplated tin covering.

[0058] The specific method of step H is as follows: after the treatment in step G, a groove is made on the anti-deposition layer by laser etching, and then the conductive layer in the grooved area is etched by chemical etching to form an insulating groove between the first conductive area and the second conductive area.

[0059] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0060] like Figures 1 to 15 The diagram shown is an embodiment of a method for manufacturing a back-contact heterojunction solar cell with low laser damage provided by the present invention.

[0061] Traditionally, all-back contact electrode technology requires a high bulk minority carrier lifetime, with alternating distribution of electron and hole extraction regions. These regions must be extracted in time before the minority carriers generated by photocurrent recombine and disappear to achieve high power generation conversion efficiency and short-circuit current. For example... Figure 14 ,15 The diagram shows an interdigitated electrode structure. Therefore, traditionally, back-contact solar cells commonly use high-performance N-type Czochralski (CZ) silicon wafers, which are relatively expensive. In recent years, cast monocrystalline silicon, with appropriate surface pretreatment, can achieve similar high volume minority carrier lifetimes to Czochralski silicon. The improved cast monocrystalline silicon wafers are also suitable for high-efficiency battery technologies, such as heterojunction (HIT / HJT / HDT) and TopCon technologies. The silicon substrates used in the heterojunction back-contact solar cells of this invention cover both conventional Czochralski and cast monocrystalline silicon wafers.

[0062] Czochralski-grown or cast-crystal silicon ingots are cut with diamond wire or slurry to form silicon wafers with a thickness of 130-250 micrometers. Although cast-crystal silicon has a higher proportion of monocrystalline silicon, the cell still has a significant proportion of polycrystalline grain boundaries and lattice defects. If cast-crystal silicon wafers are used as the substrate, they need to undergo pretreatment at different temperature ranges before being introduced into the heterojunction production process to achieve gettering and dangling bond saturation. After pretreatment, the silicon wafers first undergo tank solution pre-cleaning to remove surface organic contaminants and large particles. Then, they are de-damaged and texturized with alkaline solution to form a roughened light-trapping structure, followed by RCA cleaning (or an equivalent RCA cleaning solution formulation), and finally, HF solution to remove the surface oxide layer, deionized water cleaning, and surface drying.

[0063] like Figure 1 As shown, a first conductive film layer (including 11 and 12) is formed on the silicon wafer, and an insulating film layer 13 (including a first insulating layer and a laser absorption sacrificial layer) is formed on the first conductive film layer. The specific process is as follows:

[0064] After solution cleaning, PECVD deposition is used to prepare a surface passivation film 11 (undoped) and a doped film 12. The PECVD equipment power supply is 13.56MHz, 26MHz, or 40MHz, preferably 13.56MHz. The process gas for the intrinsic amorphous silicon film 11 contains all or a combination of silane (SiH4), hydrogen (H2), CO2, and methane (CH4). The process gas for preparing the N-type doped film contains all or a combination of SiH4, H2, CO2, and phosphine (PH3). The back contact cell of this invention uses a partial opening, and laser processing damage is controlled by a lower laser opening ratio. Furthermore, the N-type doped film uses oxygen-containing microcrystals or oxygen-free microcrystals. The oxygen-containing microcrystalline film layer includes three stages of process: (1) First, a non-oxygen-containing incubation layer with a high H2 / SiH4 ratio, which aims to promote the formation of microcrystalline state; (2) Oxygen-containing microcrystalline layer, the film formation rate of oxygen-containing microcrystalline μc-SiOx:H(N) is controlled at 0.2-2 Å / s, preferably at 0.6-0.8 Å / s; the thickness of oxygen-containing microcrystalline μc-SiOx:H(N) on the film formation surface is 40-200 Å, preferably 60-120 Å; (3) Non-oxygen-containing contact layer, which aims to reduce the contact resistance between the TCO film layer and the contact layer.

[0065] An insulating film layer deposited via PECVD is placed between the first conductive film layer (11, 12) and the second conductive film layer (26, 27) to prevent leakage current in the device. The first insulating layer is a combination of silicon nitride, silicon dioxide, silicon oxide, and silicon oxynitride. For ease of laser processing, an amorphous silicon thin film is placed on top of the first insulating layer as a sacrificial film layer for laser absorption and as an etching mask for the subsequent insulating layer. The insulating layer and the laser-absorbing sacrificial layer are as follows: Figure 1 13 shown.

[0066] like Figure 2 As shown, the laser-absorbing sacrificial layer on the silicon wafer is removed using a first laser ablation process, while the exposed insulating film layer and the underlying first conductive film layer (including 11 and 12) are removed using chemical etching, forming a P-type electrode opening region 24. The first conductive film layer still covering the insulating film layer constitutes a first conductive region 29, and the P-type electrode opening region constitutes a second conductive region 24. A pulsed laser, preferably a green laser with a pulse width of less than 20 nanoseconds, is used to remove a portion of the combined film layer 13 (after laser etching, a wet etching process containing hydrofluoric acid is applied).

[0067] like Figure 3As shown, the silicon wafer is subjected to PECVD to form a passivation film 21, an amorphous or microcrystalline film 22, and an antireflection layer 23 on the front side; and a second semiconductor film (containing an amorphous layer 26 and a p-type doped layer 27) on the back side. After chemical cleaning, the silicon wafer is subjected to PECVD to deposit the second semiconductor film (intrinsic amorphous silicon 26 and p-type doped amorphous silicon 27) on the back side. The PECVD equipment uses a power supply of 13.56MHz, 26MHz, or 40MHz, preferably 13.56MHz. The process gas for the intrinsic amorphous silicon film 26 contains all or a combination of silane (SiH4), hydrogen (H2), CO2, and methane (CH4). The process gas for preparing the p-type doped film 27 contains all or a combination of SiH4, H2, CO2, diborane (B2H6), or TMB. Figure 3 As shown, the deposition sequence on the front side of the silicon wafer is intrinsic amorphous silicon 21, amorphous or oxygen-containing microcrystalline film layer 22, and silicon nitride antireflective film layer. The process gas for the intrinsic amorphous silicon 21 on the front side (light-receiving surface) contains all or a combination of several of silane (SiH4), hydrogen (H2), CO2, and methane (CH4).

[0068] like Figure 4 As shown, the N-type silicon wafer undergoes laser ablation to remove the second conductive film layers 26 and 27 from a localized surface, and then chemical wet etching to remove the insulating film layer 13, forming an opening region 28 for the N-type electrode. To avoid laser damage (including thermal damage caused by temperature rise and excessively high local energy due to interference), preferably, the back side of the silicon wafer 00 is chemically polished to eliminate the pyramid-shaped light-trapping structure. The laser used for opening is spatially shaped to be a flat-top laser to ensure uniform energy within the processing area. The laser used for opening is a pulsed laser, preferably a green laser, violet laser, or ultraviolet laser with a pulse width of less than 100 picoseconds. To avoid a decrease in power generation efficiency due to laser damage, the opening region 28 consists of a series of non-adjacent laser processing spots, such as... Figures 10 to 13 As shown, it can be a single or multiple rows of rectangular light spots, or a single or multiple rows of circular (including elliptical) light spots.

[0069] like Figure 5As shown, a transparent conductive film (TCO) 30 and a seed metal layer 40 are prepared by PVD magnetron sputtering after the laser aperture-opening process. The TCO material can be an indium oxide thin film doped with tin oxide, titanium oxide, zinc oxide, or gallium oxide. Indium oxide (In2O3) is the main material, accounting for more than 90% by weight. Preferably, the doping material contains at least one of tin oxide, titanium oxide, zinc oxide, or gallium oxide, accounting for 0-10% by weight. The target material used for PVD can also be pure indium oxide, and then H2 or water vapor is introduced into the process gas to form a doped In2O3:H thin film. The seed metal layer can contain at least a copper layer.

[0070] like Figure 6 , 7 As shown, metal grid lines are applied after the PVD process. Preferably, one or more layers of electroplating ink 45 are printed using screen printing to transfer the metal grid line pattern to the surface of the cell. An electroplating process is used to grow a copper plating layer with a thickness of 5-100 micrometers on the back of the cell. To prevent oxidation of the copper, after the copper plating process, a protective layer with a thickness of 100 nanometers to 5 micrometers is formed on the surface of the copper grid electrode using a chemical tin replacement reaction or an electroplating tin process.

[0071] like Figure 8 , 9 As shown, a portion of the electroplated ink between gate electrodes 42 and 47 is removed using a laser continuous line etching method. Using the electroplated gate electrodes and the remaining electroplated ink as a mask, the exposed seed metal 40 and TCO film 30 are etched. Subsequently, the electroplated ink on the back side is removed using an alkaline solution. Then, using gate electrodes 42 and 47 as an etching mask, the remaining seed metal 40 on the back side is removed, and finally, the electroplated ink is removed again.

[0072] Using laser engraving instead of screen printing to define the back electrode pattern, and selective laser ablation instead of etching ink or chemical etching for openings, can greatly simplify the back contact technology process. During laser processing, local temperature rises can reach hundreds of degrees Celsius. Amorphous silicon-based heterojunction films undergo significant changes at temperatures exceeding 220 degrees Celsius. To avoid this thermal decay, the N-type conductive amorphous silicon doped layer needs to be modified into oxygen-containing or oxygen-free N-type conductive microcrystals. Simultaneously, the carrier mobility and effective doping of N-type conductive microcrystals are significantly altered compared to N-type amorphous films, greatly improving the lateral electron collection capability of the N-type collecting electrode. This allows for a significant reduction in the aperture ratio of the N-type electrode (from 10-15% for amorphous materials to around 5%). This modification can increase the throughput of laser processing equipment. Since the thermal decay of the heterojunction is related to the laser's effective area, the power conversion efficiency of the heterojunction back contact battery can also be improved accordingly.

[0073] like Figure 16The diagram shown is a schematic representation of an embodiment of a back-contact heterojunction solar cell characterized by low laser damage provided by the present invention.

[0074] A back-contact heterojunction solar cell characterized by low laser damage includes a semiconductor substrate 50, a first conductive film layer 51 disposed on a portion of a first main surface of the semiconductor substrate 50, a first insulating layer 52 disposed on the first conductive film layer 51, a laser absorption sacrificial layer 53 disposed on the first insulating layer 52, and a second conductive film layer 54 disposed on the remaining portion of the first main surface of the semiconductor substrate 50 and the first conductive film layer 51; the first conductive film layer in direct contact with the first main surface of the semiconductor substrate 50 constitutes a first conductive region 55, and the second conductive film layer in direct contact with the first main surface of the semiconductor substrate 50 constitutes a second conductive region 56.

[0075] The second conductive film layer 54 covering the first conductive area 55 has grooves or multiple countersunk holes 57 that expose the first conductive area 55.

[0076] The first insulating layer includes at least one thin film selected from silicon dioxide, silicon oxide, silicon nitride, and silicon oxynitride, and the laser absorption sacrificial layer 53 is an amorphous silicon thin film.

[0077] The first conductive film layer includes an N-type conductive film layer, which includes at least an oxygen-doped or oxygen-free microcrystalline layer; the second conductive film layer is a P-type conductive film layer.

[0078] The semiconductor substrate 50 is an N-type doped cast single-crystal or polycrystalline silicon wafer.

[0079] The back-contact heterojunction solar cell further includes a first conductive layer 58 disposed on a first conductive region 55 and electrically connected to a first conductive film layer 51, a first electrode 59 disposed on the first conductive layer 58, a second conductive layer 60 disposed on a second conductive region 56 and electrically connected to a second conductive film layer 54, and a second electrode 61 disposed on the second conductive layer 60; an insulating separation groove 62 is provided between the first conductive layer 58 and the second conductive layer 59.

[0080] The junction between the first conductive region 55 and the semiconductor substrate 50 is a heterojunction; the junction between the second conductive region 56 and the semiconductor substrate 50 is a heterojunction.

[0081] The semiconductor substrate 50 is an N-type doped cast single-crystal or polycrystalline silicon wafer.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a back-contact heterojunction solar cell with low laser damage, characterized in that: It includes step A, which involves depositing a first conductive film layer with a surface-covered insulating film layer on a portion of the first main surface of a semiconductor substrate to form a first conductive region of the first conductive type. The specific method for step A is as follows: a1, a first conductive film layer, a first insulating layer and a laser absorption sacrificial layer are sequentially formed on the first main surface of the semiconductor substrate; a2, laser etching is used to remove the laser absorption sacrificial layer in areas other than the first conductive region; a3, using chemical etching to remove the first insulating layer and the first conductive film layer that are not covered by the laser absorption sacrificial layer, so as to form a first conductive area with an insulating film layer attached to the surface; Step B: After the semiconductor substrate is processed in step A, a third passivation film layer and an optical antireflection layer are sequentially formed on its second main surface, and a second conductive film layer is formed on its first main surface. Step C: Use a laser discontinuous etching method to remove part of the second conductive film layer covering the inner region of the first conductive region; Step D: Remove the insulating film layer that does not cover the second conductive film layer by chemical etching; The first conductive film layer is an N-type conductive film layer, and the deposition process of the first conductive film layer includes forming an oxygen-doped microcrystalline layer; the second conductive film layer is a P-type conductive film layer; The deposition of the oxygen-doped microcrystalline layer comprises three process stages: first, forming a non-oxygen-containing incubation layer with a high H2 / SiH4 ratio; second, forming an oxygen-containing microcrystalline layer, wherein the deposition rate of the oxygen-containing microcrystalline N-type μc-SiOx:H is controlled at 0.2-2 Å / s, and the thickness on the deposition surface is 40-200 Å; and third, forming a non-oxygen-containing contact layer. The specific method of step C is to use laser discontinuous etching to remove part of the second conductive film layer covering the middle area of ​​the first conductive region, so that the second conductive film layer covering the first conductive region forms a hole array that exposes the insulating film layer. Adjacent holes do not contact each other, and the hole array consists of one or more rows of holes. The laser is a flat-top laser that has undergone spatial shaping.

2. The method for manufacturing a back-contact heterojunction solar cell according to claim 1, characterized in that: The specific process for the laser absorption sacrificial layer is to deposit an amorphous silicon thin film on a first insulating layer as a substrate.

3. The method for manufacturing a back-contact heterojunction solar cell according to claim 1, characterized in that: The optical refractive index of the oxygen-doped microcrystalline layer after film formation is between 2.2 and 3.

1.

4. The method for manufacturing a back-contact heterojunction solar cell according to any one of claims 1-3, characterized in that: It also includes the following steps, Step E: After processing in step D, a conductive layer is formed on the surface of the first conductive region and the second conductive region. Step F: An anti-deposition layer is formed on the conductive layer by printing to create the electrode pattern to be deposited; Step G: An electrode is formed on the surface of the region of the conductive layer that is not covered by the anti-deposition layer; Step H involves creating grooves in the anti-deposited layer and the conductive layer area it covers using laser etching or a combination of laser etching and chemical etching; the grooves form a separating insulation between the first conductive area and the second conductive area.

5. The method for manufacturing a back-contact heterojunction solar cell according to claim 4, characterized in that: The specific method of step E is to sequentially fabricate a transparent conductive film and a metal conductive film on the first main surface of the semiconductor substrate after the treatment in step D to form a conductive layer.

6. The method for manufacturing a back-contact heterojunction solar cell according to claim 4, characterized in that: The specific method of step F is to print anti-electroplating ink on the conductive layer obtained by step E.

7. The method for manufacturing a back-contact heterojunction solar cell according to claim 4, characterized in that: The specific method of step G is to use electroplating to fabricate the first conductive region electrode and the second conductive region electrode on the first conductive region and the second conductive region after the treatment in step C.

8. The method for manufacturing a back-contact heterojunction solar cell according to claim 4, characterized in that: The specific method of step H is as follows: after the treatment in step G, a groove is made on the anti-deposition layer by laser etching, and then the conductive layer in the grooved area is etched by chemical etching to form an insulating groove between the first conductive area and the second conductive area.

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