CN110676343A

CN110676343A - Back contact solar cell and preparation method thereof

Info

Publication number: CN110676343A
Application number: CN201810620412.3A
Authority: CN
Inventors: 舒欣
Original assignee: Beijing Juntai Innovation Technology Co Ltd
Current assignee: Deyun Chuangxin (Beijing) Technology Co.,Ltd.
Priority date: 2018-06-15
Filing date: 2018-06-15
Publication date: 2020-01-10
Also published as: WO2019237561A1

Abstract

The invention discloses a back contact solar cell and a preparation method thereof, and belongs to the field of solar cells. The preparation method comprises the following steps: forming a first functional area on the back of the crystalline silicon substrate, wherein the first functional area comprises a reserved area and a removed area; forming a protective layer on the reserved area; removing the removal region, and forming a groove on the back of the crystalline silicon substrate; forming a second functional region in the groove; removing the protective layer; wherein the first functional region and the second functional region have different conductivity types. The preparation method provided by the embodiment of the invention can be used for preparing the back pattern with insulating property only by adopting the mask once, and has the advantages of simple process and low cost. The back contact solar cell with the height difference between the first functional area and the second functional area can be prepared by the method, good insulation is formed, and the reduction of open-circuit voltage, short-circuit current and filling factors caused by the conduction of the first functional area and the second functional area is avoided, so that the energy conversion efficiency of the cell is improved.

Description

Back contact solar cell and preparation method thereof

Technical Field

The invention relates to the field of solar cells, in particular to a back contact solar cell and a preparation method thereof.

Background

The back contact solar cell is a cell in which a P region (positive electrode) and an N region (negative electrode) are both disposed on the back side (non-light-receiving surface) of the cell, and the P region and the N region are located on the same horizontal plane and are relatively close to each other, so that the P region and the N region are easily electrically conducted, the open-circuit voltage, the short-circuit current and the fill factor of the cell are reduced, and the improvement of the cell energy conversion efficiency is affected.

In order to manufacture a high-efficiency solar cell, a back pattern with good insulating property needs to be manufactured between a P region and an N region. In the prior art, the back pattern is mostly prepared by a photoetching method and a laser method.

The inventor finds that the prior art has at least the following problems:

the back pattern prepared by the photoetching technology needs to be subjected to photoetching for multiple times, so that the whole process is relatively complex, the photoetching process is expensive, and the production of a flat solar cell is not facilitated; and the back pattern is prepared by adopting a laser process, so that the silicon wafer body is easy to damage and the surface is easy to damage, an additional process is needed to remove the damage, and the problem of complex process also exists.

Disclosure of Invention

The invention provides a back contact solar cell and a preparation method thereof, which can solve the technical problems.

Specifically, the method comprises the following technical scheme:

in one aspect, the present invention provides a method for manufacturing a back contact solar cell, the method comprising:

forming a first functional area on the back of the crystalline silicon substrate, wherein the first functional area comprises a reserved area and a removed area;

forming a protective layer on the reserved area;

removing the removal region, and forming a groove on the back of the crystalline silicon substrate;

forming a second functional region in the groove;

removing the protective layer;

wherein the first functional region and the second functional region have different conductivity types.

In one possible design, after the removing the protective layer, the preparation method further includes: forming a first metal electrode on the first functional region of the retention region; and forming a second metal electrode on the second functional region.

In one possible design, the forming a protective layer on the reserved area includes:

forming the protective layer on the remaining region by a screen printing process; and/or spreading a cover plate on the reserved area to form the protective layer.

In one possible design, the forming the protective layer on the reserved area by a screen printing process includes:

laying a screen printing plate in the first functional area, wherein the screen printing plate covers the removing area and exposes the reserved area;

printing blocking slurry on the first functional area through the screen printing screen;

drying and curing the barrier slurry; preferably, the barrier paste comprises a polymeric material and/or a paraffin wax.

And removing the screen printing plate, and forming the protective layer on the reserved area.

In one possible design, the removing the removal region and forming a trench in the back side of the crystalline silicon substrate includes:

removing the removal region through an etching process to expose the back surface of the crystalline silicon substrate;

etching the groove on the back of the crystalline silicon substrate; preferably, the depth of the groove is 0.5-5 um.

In one possible design, the removing the protective layer includes:

the protective layer is removed by at least one of physical stripping and chemical etching.

In one possible design, the method of making further comprises:

and forming a passivation layer and/or an antireflection layer on the front surface of the crystalline silicon substrate.

In one possible design, before forming the passivation layer and/or the anti-reflection layer on the front side of the crystalline silicon substrate, the preparation method further includes:

and texturing the front surface of the crystalline silicon substrate.

In one possible design, the reserved areas and the removed areas are arranged alternately.

In one possible design, when the first functional region is an N region, the forming a first functional region on the back side of the crystalline silicon substrate includes:

forming a first intrinsic thin film layer on the back surface of the crystalline silicon substrate;

forming an n-type doped silicon-based thin film layer on the first intrinsic thin film layer;

forming a first transparent conducting layer on the n-type doped silicon-based thin film layer;

the first intrinsic thin film layer, the n-type doped silicon-based thin film layer and the first transparent conductive layer form the first functional region.

In one possible design, the forming a second functional region in the trench includes:

forming a second intrinsic thin film layer in the trench;

forming a p-type doped silicon-based thin film layer on the second intrinsic base thin film;

forming a second transparent conducting layer on the p-type doped silicon-based thin film layer;

the second intrinsic thin film layer, the p-type doped silicon-based thin film layer and the second transparent conductive layer form the second functional region.

In another aspect, the invention also provides a back contact solar cell prepared by any one of the above-mentioned preparation methods.

The technical scheme provided by the embodiment of the invention has the beneficial effects that at least:

the preparation method provided by the embodiment of the invention can prepare the back pattern with insulating property by only adopting the mask once, avoids adopting a photoetching method and a laser method, and has simple process and low cost. The back contact solar cell with the height difference between the first functional area and the second functional area can be prepared by the method, the height difference prevents the first functional area and the second functional area from being contacted, good insulation is formed, and therefore the reduction of open-circuit voltage, short-circuit current and filling factors caused by the conduction of the first functional area and the second functional area is avoided, and the energy conversion efficiency of the cell is improved.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a method for manufacturing a back contact solar cell according to an embodiment of the present invention;

fig. 2a to fig. 2j are schematic diagrams of a back contact solar cell manufacturing process according to an embodiment of the present invention;

fig. 3 is a schematic view of a back contact solar cell fabricated according to an embodiment of the present invention.

The reference numerals in the drawings denote:

a 1-crystalline silicon substrate;

2-a first intrinsic thin film layer;

3-n type silicon-based doped thin film layer;

4-a first transparent conductive layer;

5-a protective layer;

6-a second intrinsic thin film layer;

7-p type silicon-based doped thin film layer;

8-a second transparent conductive layer;

9-a passivation layer;

10-an anti-reflection layer;

11-a first metal electrode;

12-second metal electrode.

Detailed Description

In order to make the technical solutions and advantages of the present invention clearer, the following will describe embodiments of the present invention in further detail with reference to the accompanying drawings. Unless defined otherwise, all technical terms used in the examples of the present invention have the same meaning as commonly understood by one of ordinary skill in the art.

In a first aspect, an embodiment of the present invention provides a method for manufacturing a back contact solar cell, as shown in fig. 1, the method includes:

step S1, forming a first functional area on the back of the crystalline silicon substrate 1, wherein the first functional area comprises a reserved area and a removed area;

step S2, forming a protective layer 5 on the reserved area;

step S3, removing the removal area, and forming a groove on the back of the crystal silicon substrate 1;

step S4, forming a second functional area in the groove;

step S5, removing the protective layer 5;

During preparation, a first functional area is formed on the back surface of the crystalline silicon substrate 1, and then a mask is formed by using the protective layer 5 to protect a reserved area of the first functional area; forming a groove on the back of the crystalline silicon substrate 1 corresponding to the unmasked removal area, and forming a second functional area in the groove; and finally, removing the mask (the protective layer 5) to prepare the back contact solar cell.

The preparation method provided by the embodiment of the invention can prepare the back pattern with insulating property by only adopting the mask once, can avoid adopting a photoetching method and a laser method, and has simple process and low cost. The back contact solar cell with the height difference between the first functional area and the second functional area can be prepared by the method, the height difference prevents the first functional area and the second functional area from being contacted, good insulation is formed, and the reduction of open-circuit voltage, short-circuit current and filling factors caused by the conduction of the first functional area and the second functional area is avoided, so that the energy conversion efficiency of the cell is improved.

In the above-described production method, "the first functional region is different in conductivity type from the second functional region" may be understood as meaning that the first functional region is a positive electrode or a negative electrode, and correspondingly, the second functional region is a negative electrode or a positive electrode; and further may be understood as the first functional region being a P region or an N region, and correspondingly, the second functional region being an N region or a P region.

In step S1, taking the case where the first functional region is an N region as an example, first, the first functional region is formed on the back surface of the crystalline silicon substrate 1. Specifically, N regions having different stacked structures may be formed according to actual circumstances. To achieve better cell energy conversion efficiency, for example, as shown in fig. 2a, forming an N region on the back side of the crystalline silicon substrate 1 may include the following steps:

step S101, forming a first intrinsic thin film layer 2 on the back of a crystalline silicon substrate 1;

step S102, forming an n-type doped silicon-based thin film layer 3 on the first intrinsic thin film layer 2;

step S103, forming a first transparent conducting layer 4 on the n-type doped silicon-based thin film layer 3;

the first intrinsic thin film layer 2, the n-type silicon-based doped thin film layer 3 and the first transparent conductive layer 4 form a first functional region.

Wherein, the first functional region can be formed on the back surface of the crystalline silicon substrate 1 by a deposition method.

Illustratively, the first intrinsic thin film layer 2 and the n-type doped silicon-based thin film layer 3 may be sequentially deposited on the back surface of the crystalline silicon substrate 1 in a stacked manner by using a PECVD deposition method (chemical vapor deposition method), and the first transparent conductive layer 4 may be deposited on the n-type doped silicon-based thin film layer 3 by using a PVD deposition method (physical vapor deposition method).

Further, the crystalline silicon substrate 1 can be an n-type monocrystalline silicon piece or a p-type monocrystalline silicon piece, preferably, the n-type monocrystalline silicon piece is selected as the crystalline silicon substrate 1, and the thickness of the n-type monocrystalline silicon piece can be 200 μm and the resistivity is 1-10 Ω cm; the first intrinsic thin film layer 2 may be an amorphous silicon film (a-Si: H) or an amorphous silicon oxygold film (a-SiO)_xH), and the thickness of the first intrinsic thin film layer 2 can be 1-10 nm; the n-type silicon-doped thin film layer 3 can be a phosphorus-doped amorphous silicon layer, such as any one of a-Si: H, a-SiOx: H, μ c-SiOx: H, etc., and the thickness of the n-type silicon-doped thin film layer 3 can be 1-10 nm; the first transparent conductive layer 4 may be a transparent conductive oxide layer such as any one of an ITO film (tin-doped indium oxide transparent conductive film), an IWO film (tungsten-doped indium oxide transparent conductive film), or an ICO film (cesium-doped indium oxide transparent conductive film), and the thickness of the first transparent conductive layer 4 may be made 10 to 200 nm.

Then, a reserve region and a removal region are divided on the first functional region on the back surface of the crystalline silicon substrate 1. In a preferred embodiment, the reserved areas and the removed areas are alternately arranged on the first functional area. The reserved area is an N area or a P area of the finally formed back contact solar cell, and the removed area is a P area or an N area of the finally formed back contact solar cell.

In actual preparation, the shapes of the reserved area and the removed area can be set according to actual needs, and in consideration of the simplicity of the preparation process, the reserved area and the removed area can be alternately arranged in a long strip shape, such as a rectangle. It should be noted that the area ratio of the retention region and the removal region is not strictly limited in the embodiments of the present invention, and in actual preparation, the area ratio can be determined by simulation and optimization as needed. For example, the area ratio of the adjacent P region and N region may be set to 3: 1.

in addition, it can be understood that, before the first functional region is deposited, the crystalline silicon substrate 1 can be subjected to damage layer removal (SDR) and standard RCA cleaning to remove organic matter, particles, metal ions and other contaminants on the surface of the silicon wafer, so as to form a clean silicon wafer surface.

For step S2, the protection layer 5 is used to protect the reserved area from damage of subsequent processes. Forming the protective layer 5 on the remaining area can be achieved in various ways.

In one possible embodiment, the protective layer 5 may be formed on the remaining region by a screen printing process. Illustratively, as shown in fig. 2b, the following steps may be included:

step S201, laying a screen printing plate in a first functional area, covering the removal area with the screen printing plate, and exposing the reserved area;

step S202, printing blocking slurry on a first functional area through a screen printing plate;

step S203, drying and curing the blocking slurry;

and step S204, removing the screen printing plate and forming a protective layer 5 on the reserved area.

The blocking slurry may be at least one of a polymer material, a paraffin material, and the like. Specifically, the barrier slurry may be dried using a drying oven.

The screen printing process has the advantage of high alignment precision, and the formed protective layer 5 can accurately cover the reserved area by adopting the screen printing process, so that the design requirement is met. And the protective layer 5 is formed by adopting a screen printing method, the used blocking slurry is low in price, and the production cost can be reduced.

In another possible embodiment, a cover plate may also be used to form the protective layer 5.

Illustratively, the cover sheet may be laid on the reserved area to form the protective layer 5.

When the device is used, the cover plate can be fastened on the reserved area by the fastening piece, so that the cover plate is attached to the reserved area, the reserved area is protected, and the reserved area is prevented from being damaged by a subsequent process.

For the step S3, an etching process may be used to remove the removal region and form a trench on the back side of the crystalline silicon substrate 1. As shown in fig. 2 c-2 e, the following steps may be included:

s301, removing the removal area through an etching process to expose the back surface of the crystalline silicon substrate 1;

step S302, a groove is etched on the back of the crystalline silicon substrate 1.

Wherein the removal region can be removed by an etching (e.g., wet chemical etching) process to expose the back surface of the silicon substrate; furthermore, a wet chemical etching method can be adopted, a groove is etched on the back of the crystalline silicon substrate 1 by controlling the etching time, and finally a height difference is formed on the back of the crystalline silicon substrate 1. The height difference can form good insulation between the first functional region and the second functional region, and the depth of the trench can be 0.5-5um, considering that in practical application, the trench may not achieve the insulation effect when being too shallow, and damage to the crystalline silicon substrate 1 may be caused when being too deep.

Specifically, the first transparent conductive layer 4 of the removal region (not protected by the protective layer 5 mask) may be first etched away using a first etching solution (e.g., HF, HCl, etc.), as shown in fig. 2 c;

then, etching off the n-type doped silicon-based thin film layer 3 and the first intrinsic thin film layer 2 in the removal region (not protected by the protective layer 5 mask) by using a second etching solution (such as KOH, TMAH and the like), as shown in FIG. 2 d;

and finally, etching a groove on the back surface of the crystalline silicon substrate 1 by using a third etching solution (such as a solution of KOH, TMAH, etc.) and controlling the chemical etching time, as shown in fig. 2 e.

The wet chemical etching method has the advantages of simple process, low cost, convenient control and no damage, and can be used for conveniently removing amorphous silicon and preparing a required back pattern without causing additional damage.

For the step S4, when the first functional region is an N region, the second functional region can be a P region, and the second functional region can be formed in the trench, as shown in fig. 2f, which includes the following steps:

step S401, forming a second intrinsic base film in the groove;

step S402, forming a p-type doped silicon-based film on the second intrinsic base film;

step S403, forming a second transparent conducting layer 8 on the p-type doped silicon-based film;

the second intrinsic base film, the p-type doped silicon-based film and the second transparent conductive layer 8 form a second functional region.

Wherein the second functional region can be formed in the trench by a deposition method.

Illustratively, a PECVD deposition method may be used to sequentially deposit the second intrinsic thin film layer 6 and the p-type doped silicon-based thin film layer 7 on the back surface of the crystalline silicon substrate 1, and a PVD deposition method may be used to deposit the second transparent conductive layer 8 on the p-type doped silicon-based thin film layer 7. It will be appreciated that the second functional region formed on the back side of the crystalline silicon substrate 1, i.e. covering the trench, also covers the protective layer 5.

Further, the second intrinsic thin film layer 6 may be an amorphous silicon film (a-Si: H) or an amorphous silicon oxygold film (a-SiO)_xH) and the thickness of the second intrinsic thin film layer 6 may be 1-10 nm; the p-type doped silicon-based thin film layer 7 can be a boron-doped amorphous silicon layer, such as any one of a-Si: H, a-SiOx: H, μ c-SiOx: H, etc., and the thickness of the p-type doped silicon-based thin film layer 7 can be 1-10 nm; the second transparent conductive layer 8 may be a transparent conductive oxide layer, such as any one of an ITO film, an IWO film, or an ICO film,and the thickness of the second transparent conductive layer 8 can be made 10-200 nm.

In addition, it can be understood that before the second functional region is deposited, the crystal silicon substrate 1 can be subjected to RCA cleaning to remove the residual chemical solution, so as to form a clean silicon wafer surface.

For step S5, considering that the second functional region covers the trench and also covers the protection layer 5, at least one of physical stripping and chemical etching may be used to remove the protection layer 5, and simultaneously strip the second functional region (the second intrinsic thin film layer 6, the p-type doped silicon-based thin film layer 7 and the second transparent conductive layer 8) on the protection layer 5 to expose the first functional region.

Illustratively, as shown in fig. 2g, the barrier paste (the protection layer 5) may be removed by using a barrier paste removing solution (e.g., a hydrofluoric acid HF solution, etc.), and the second intrinsic thin film layer 6, the p-type doped silicon-based thin film layer 7 and the second transparent conductive layer 8 on the protection layer 5 may be stripped off, so that the first functional region and the second functional region are simultaneously presented on the back surface of the crystalline silicon substrate 1.

It should be noted that when the deposition method is used to form the second functional region in the trench, the second intrinsic thin film layer 6 can be formed on the sidewall of the trench at the same time (as shown in fig. 2 g); and when the protective layer 5 is removed by the above method, the second intrinsic thin film layer 6 may remain, and the second intrinsic thin film layer 6 may form further insulation between the first functional region and the second functional region.

In the back contact solar cell, the front surface of the crystalline silicon substrate 1 is a light receiving surface of the cell, and in order to further improve the energy conversion efficiency of the cell, the preparation method may further comprise:

step S6, forming a passivation layer 9 and/or an anti-reflection layer 10 on the front side of the crystalline silicon substrate 1.

It is understood that before this step, the crystalline silicon substrate 1 may also be subjected to RCA cleaning to remove residual chemical solution to form a clean silicon wafer surface.

Illustratively, as shown in fig. 2i, a PECVD deposition method may be used to deposit an intrinsic amorphous silicon layer on the front surface of the crystalline silicon substrate 1 to form a passivation layer 9, and the thickness of the intrinsic amorphous silicon layer may be 1-10 nm; further, a transparent conductive layer (e.g., TCO film) having a thickness of 10 to 200nm may be deposited on the passivation layer 9 by PVD deposition to form the anti-reflection layer 10.

Further, a phosphorus-doped amorphous silicon layer, which may have a thickness of 1-10nm, may be formed on the front surface of the crystalline silicon substrate 1, and a Front Surface Field (FSF) may be formed on the front surface of the crystalline silicon substrate 1, and may be positioned between the passivation layer 9 and the anti-reflection layer 10 in actual manufacturing.

It is understood that, before forming the passivation layer 9 and/or the anti-reflection layer 10 on the front side of the crystalline silicon substrate 1, as shown in fig. 2h, the preparation method further includes: the front surface of the crystalline silicon substrate 1 is textured.

Illustratively, the front side of the crystalline silicon substrate 1 is textured in an alkaline solution (KOH or TMAH) (at this time, the first transparent conductive layer 4 and the second transparent conductive layer 8 on the back side can protect the back side pattern).

Pyramid size can be formed on the front surface of the crystalline silicon substrate 1 by the texturing process to reduce the reflection loss of the cell surface light.

In the back contact solar cell, in order to facilitate the carrier extraction generated in the solar cell, as shown in fig. 2j, the preparation method may further include:

step S7, forming a first metal electrode 11 on the first functional region of the reserved region; and forming a second metal electrode 12 on the second functional region.

Illustratively, the first metal electrode 11 and the second metal electrode 12 may each be a silver grid and/or a copper electrode.

During preparation, silver grids can be respectively printed on the first transparent electrode layer and the second transparent electrode layer through a screen printing process; and/or preparing copper electrodes on the first transparent electrode layer and the second transparent electrode layer respectively by electroplating.

For convenience of explanation, the preparation method of the present invention is described above by taking the case where the first functional region is an N region and the second functional region is a P region as an example, and the case where the first functional region is a P region and the second functional region is an N region is equivalent thereto.

In a second aspect, the embodiment of the present invention further provides a back contact solar cell, which is prepared by any one of the preparation methods mentioned in the first aspect.

According to the back contact solar cell prepared by the preparation method provided by the embodiment of the invention, the first functional region and the second functional region formed on the crystalline silicon substrate 1 have a height difference, the height difference prevents the first functional region and the second functional region from being contacted, good insulation is formed, and the reduction of open-circuit voltage, short-circuit current and filling factor caused by the conduction of the first functional region and the second functional region is avoided, so that the energy conversion efficiency of the cell is improved.

As an example, the solar cell prepared by the above method may be as shown in fig. 3,

the back contact solar cell includes:

the crystal silicon substrate 1, the back of the crystal silicon substrate 1 is provided with a first surface and a second surface with height difference;

the first intrinsic thin film layer 2, the n-type doped silicon-based thin film layer 3, the first transparent conducting layer 4 and the first metal electrode 11 are sequentially arranged on the first surface; and

the second intrinsic thin film layer 6, the p-type doped silicon-based thin film layer 7, the second transparent conducting layer 8 and the second metal electrode 12 are sequentially arranged on the second surface;

the back surface of the crystalline silicon substrate 1 is also provided with a third surface, and the third surface is positioned between the first surface and the second surface and is vertical to the first surface and the second surface; an insulating layer is arranged on the third surface.

Fig. 3 is a schematic view of a back contact solar cell fabricated according to an embodiment of the present invention. The reserved regions and the removed regions are alternately arranged on the back surface of the crystalline silicon substrate 1, and further, the P regions and the N regions are alternately formed on the back surface of the crystalline silicon substrate 1.

The working principle of the back contact solar cell is as follows: forming a PN junction between the crystalline silicon substrate 1 and the n-type doped silicon-based thin film layer 3 and the p-type doped silicon-based thin film layer 7, wherein when incident light irradiates on the PN junction, carriers (photo-generated electrons and photo-generated holes) are generated, and the photo-generated electrons are collected in the first transparent conducting layer 4 through the first intrinsic thin film layer 2 and the n-type doped silicon-based thin film layer 3 and then are led out through the first metal electrode 11; and the photogenerated holes are collected in the second transparent conductive layer 8 through the second intrinsic thin film layer 6 and the p-type doped silicon-based thin film layer 7 and then are guided out by the second metal electrode 12. Wherein the first intrinsic thin film layer 2 and the second intrinsic thin film layer 6 are used for passivating the surface defects of the crystalline silicon substrate 1.

The back contact solar cell forms insulation between the N area and the P area through the first surface and the second surface with height difference, so that the N area and the P area arranged on the back contact solar cell have height difference; meanwhile, a third surface perpendicular to the first surface and the second surface is arranged between the first surface and the second surface, and an insulating layer is arranged on the third surface, so that insulation between the N region and the P region is further formed, the reduction of open-circuit voltage, short-circuit current and filling factors caused by the conduction of the N region and the P region is avoided, and the energy conversion efficiency of the battery is improved.

Wherein the insulating layer may be the first intrinsic thin film layer 2 or the second intrinsic thin film layer 6.

It is understood that x may be 1 to 2 for SiOx referred to in the examples of the present invention.

The above description is only for facilitating the understanding of the technical solutions of the present invention by those skilled in the art, and is not intended to limit the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for fabricating a back contact solar cell, the method comprising:

forming a protective layer on the reserved area;

forming a second functional region in the groove;

removing the protective layer;

2. The method of manufacturing according to claim 1, further comprising, after the removing the protective layer: forming a first metal electrode on the first functional region of the retention region; and forming a second metal electrode on the second functional region.

3. The method of claim 1, wherein the forming a protective layer on the reserved area comprises:

4. The method of manufacturing according to claim 3, wherein the forming of the protective layer on the retention region by a screen printing process includes:

drying and curing the barrier slurry; preferably, the barrier slurry comprises a polymeric material and/or paraffin;

5. The method of claim 1, wherein the removing the removal region and forming a trench in the back side of the crystalline silicon substrate comprises:

6. The method of claim 1, wherein the removing the protective layer comprises:

7. The method of manufacturing according to claim 1, further comprising:

8. The manufacturing method according to claim 7, wherein before forming the passivation layer and/or the antireflection layer on the front side of the crystalline silicon substrate, the manufacturing method further comprises:

and texturing the front surface of the crystalline silicon substrate.

9. The production method according to claim 1, wherein the retention areas and the removal areas are alternately arranged.

10. The method for manufacturing a silicon substrate according to any one of claims 1 to 9, wherein when the first functional region is an N region, the forming of the first functional region on the back surface of the silicon substrate includes:

11. The method of claim 10, wherein the forming a second functional region in the trench comprises:

forming a second intrinsic thin film layer in the trench;

12. A back contact solar cell, wherein the back contact solar cell is prepared by the method of any one of claims 1-11.