Back contact cell and method of manufacturing the same, photovoltaic module

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a back contact cell and a manufacturing method thereof and a photovoltaic module, and the manufacturing method comprises the following steps: providing a substrate with a first surface and a second surface opposite along a first direction, the second surface has first areas and second areas arranged alternately along a second direction; forming a dielectric layer on the second surface; forming a doping layer and a silicon glass layer with doping elements on the side of the dielectric layer away from the substrate in sequence, the mole percentage content of the doping elements in the silicon glass layer is 5%-10%; removing the silicon glass layer located on the first area or the second area; and performing etching treatment with the remaining silicon glass layer as a mask layer, and removing the doping layer and the dielectric layer not covered by the mask layer, so that the manufacturing efficiency of the back contact cell is improved at least.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaics, and in particular to a back contact cell, a manufacturing method thereof, and a photovoltaic module. BACKGROUND

[0002] Solar cells are increasingly used as a sustainable clean energy source. A solar cell is a device that uses the photovoltaic principle to generate carriers to convert the light energy of the sun into electrical energy. Grid lines are usually used in solar cells to lead out carriers, so as to effectively utilize electrical energy. The mainstream types of current solar cells include BC cells (Back Contact), TOPCON (Tunnel Oxide Passivated Contact) cells, PERC cells (Passivated emitter and real cell), and heterojunction cells.

[0003] To further avoid the shading of grid lines on the front surface of a solar cell, research on BC cells (Back Contact) is increasingly in-depth, but grid lines of different polarities are both located on the back surface of a solar cell, which requires repeated use of a mask plate technology in the process of preparing a BC cell, greatly increasing the process difficulty and production cost, and reducing the preparation efficiency. SUMMARY

[0004] The embodiments of the present application provide a back contact cell, a manufacturing method thereof, and a photovoltaic module, which at least help to improve the manufacturing efficiency of a back contact cell.

[0005] According to some embodiments of the present application, the embodiments of the present application provide a manufacturing method of a back contact cell, comprising: providing a substrate, the substrate having a first surface and a second surface opposite to each other along a first direction, the second surface having a first region and a second region arranged alternately along a second direction; forming a dielectric layer on the second surface; forming a doped layer and a silicon glass layer stacked on a side of the dielectric layer away from the substrate, the doped layer and the silicon glass layer both having a doping element, and the mole percentage content of the doping element in the silicon glass layer being 5% to 10%; removing the silicon glass layer on the first region or the second region; and performing etching treatment with the remaining silicon glass layer as a mask layer to remove the doped layer and the dielectric layer not covered by the mask layer.

[0006] In some embodiments, the step of forming the doped layer and the silicon glass layer comprises: forming a semiconductor layer on a side of the medium layer away from the substrate; performing a doping treatment on the semiconductor layer to convert the semiconductor layer into the doped layer; and forming the silicon glass layer on a side of the doped layer away from the substrate, and controlling the mole percentage of the doping element in the silicon glass layer to be 5% to 10%.

[0007] In some embodiments, the medium layer comprises a first medium layer, the semiconductor layer comprises a first semiconductor layer, the doping element comprises boron, the doped layer formed after the doping treatment comprises a first doped layer, and the silicon glass layer comprises a borosilicon glass layer, wherein the mole percentage of boron in silicon oxide in the borosilicon glass layer is 5% to 10%.

[0008] In some embodiments, the step of performing the doping treatment comprises: first performing a first diffusion treatment, and then performing a first push joint treatment; the step of performing the first diffusion treatment comprises: placing the substrate after forming the first semiconductor layer into a reaction chamber, and introducing boron trichloride into the reaction chamber; the step of performing the first push joint treatment comprises: first performing a first oxygen-containing push joint treatment, introducing a mixed gas of boron trichloride and oxygen into the reaction chamber; and then performing a first oxygen-free push joint treatment, introducing boron trichloride into the reaction chamber.

[0009] In some embodiments, the gas flow of boron trichloride introduced into the reaction chamber is 50sccm to 200sccm; and / or, the ratio of the processing time of the first oxygen-containing push joint treatment to the processing time of the first oxygen-free push joint treatment is 1:20 to 1:3.

[0010] In some embodiments, in the step of performing the first oxygen-containing push joint treatment, the ratio of the gas flow of oxygen to the gas flow of boron trichloride is 2 to 10.

[0011] In some embodiments, the process temperature of the first diffusion treatment is 800°C to 900°C; and / or, the push joint temperature of the first push joint treatment is 900°C to 1050°C.

[0012] In some embodiments, the medium layer comprises a second medium layer, the semiconductor layer comprises a second semiconductor layer, the doping element comprises phosphorus, the doped layer formed after the doping treatment comprises a second doped layer, and the silicon glass layer comprises a phosphosilicon glass layer, wherein the mole percentage of phosphorus in silicon oxide in the phosphosilicon glass layer is 5% to 10%.

[0013] In some embodiments, the step of removing the silicon glass layer comprises: performing laser treatment on the silicon glass layer located on the first region or the second region to form a modified layer; removing the modified layer in the step of performing the etching treatment; and performing the etching treatment on the remaining silicon glass layer as a mask layer to remove the doped layer and the medium layer covered by the modified layer in the step of performing the etching treatment.

[0014] In some embodiments, the medium layer comprises a first medium layer, the doped element comprises boron, the doped layer formed after the step of performing the doping treatment comprises a first doped layer, and the silicon glass layer comprises a borosilicon glass layer; the step of performing the laser treatment comprises: performing the laser treatment on the borosilicon glass layer located on the second region to convert the borosilicon glass layer located on the second region into a first modified layer; and the step of performing the etching treatment comprises: removing the first modified layer and removing the first doped layer and the first medium layer covered by the first modified layer with the borosilicon glass layer remaining on the first region as a mask layer.

[0015] In some embodiments, the medium layer comprises a second medium layer, the doped element comprises phosphorus, the doped layer formed after the step of performing the doping treatment comprises a second doped layer, and the silicon glass layer comprises a phosphosilicon glass layer; the step of performing the laser treatment comprises: performing the laser treatment on the phosphosilicon glass layer located on the first region to convert the phosphosilicon glass layer located on the first region into a second modified layer; and the step of performing the etching treatment comprises: removing the second modified layer and removing the second doped layer and the second medium layer covered by the second modified layer with the phosphosilicon glass layer remaining on the second region as a mask layer.

[0016] According to some embodiments of the present application, another aspect of the embodiments of the present application further provides a back contact cell, comprising a back contact cell formed by the manufacturing method of the back contact cell according to any one of the above.

[0017] According to some embodiments of the present application, still another aspect of the embodiments of the present application further provides a photovoltaic module, comprising: a cell string connected by a plurality of back contact cells formed by the manufacturing method of the back contact cell according to any one of the above or connected by a plurality of back contact cells according to any one of the above; an encapsulation adhesive film used for covering a surface of the cell string; and a cover plate used for covering a surface of the encapsulation adhesive film away from the cell string.

[0018] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0019] In the step of forming the silicon glass layer, the mole percentage content of the doping element in the silicon glass layer is controlled to be 5% to 10%. On the one hand, the formed silicon glass layer has high compactness, so as to improve the etching resistance of the silicon glass layer in the subsequent step of taking the silicon glass layer as a mask layer, so as to avoid that the doping layer and the medium layer which need to be reserved are over-etched, thereby improving the yield of the finally manufactured back contact cell. On the other hand, the mole percentage content of the doping element in the silicon glass layer is moderate, which is beneficial to improve the forming rate of the silicon glass layer, thereby improving the manufacturing efficiency of the back contact cell. In addition, in the step of patterning the doping layer and the medium layer, the silicon glass layer is directly taken as a mask layer, and no additional mask is needed, which is beneficial to simplify the manufacturing process of the back contact cell, thereby further improving the manufacturing efficiency of the back contact cell. In this way, the yield of the finally manufactured back contact cell is improved, and the manufacturing efficiency of the back contact cell is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] One or more embodiments are illustrated by way of example in the figures that form a part of this disclosure and which are shown by way of illustration in the drawings. Unless otherwise noted, the drawings provided herein are not to scale and are shown as is most appropriate for further understanding the embodiments disclosed herein. Although the drawings represent embodiments, the drawings are not necessarily to scale and that a particular feature shown with respect to one embodiment can be different in the context of another embodiment. Furthermore, the drawings are not intended to limit the scope of the disclosure to the precise arrangements shown and described in the drawings.

[0021] Figure 1 A process flow chart corresponding to the manufacturing method of the back contact cell provided by an embodiment of the present application;

[0022] Figure 2 A partial cross-sectional view of a substrate in the manufacturing method of the back contact cell provided by an embodiment of the present application;

[0023] Figure 3 A partial cross-sectional view after forming the first medium layer in the manufacturing method of the back contact cell provided by an embodiment of the present application;

[0024] Figure 4 A partial cross-sectional view after forming the first semiconductor layer in the manufacturing method of the back contact cell provided by an embodiment of the present application;

[0025] Figure 5 A partial cross-sectional view after the doping treatment in the manufacturing method of the back contact cell provided by an embodiment of the present application;

[0026] Figure 6A partial cross-sectional view of a back contact cell after laser processing in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0027] Figure 7 A partial cross-sectional view of a back contact cell after etching processing in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0028] Figure 8 A partial cross-sectional view of a back contact cell after forming a second dielectric layer in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0029] Figure 9 A partial cross-sectional view of a back contact cell after forming a second semiconductor layer in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0030] Figure 10 Another partial cross-sectional view of a back contact cell after doping processing in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0031] Figure 11 Another partial cross-sectional view of a back contact cell after laser processing in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0032] Figure 12 Another partial cross-sectional view of a back contact cell after etching processing in a manufacturing method of a back contact cell according to an embodiment of the present application;

[0033] Figure 13 A partial perspective view of a cell string in a photovoltaic module according to another embodiment of the present application;

[0034] Figure 14 A partial cross-sectional view of a photovoltaic module according to another embodiment of the present application.

[0035] BRIEF DESCRIPTION OF DRAWINGS

[0036] 100, substrate; 110, first surface; 120, second surface; 1201, first region; 1202, second region; 101, dielectric layer; 111, first dielectric layer; 121, second dielectric layer; 102, doped layer; 112, first doped layer; 122, second doped layer; 103, silicon glass layer; 113, borosilicon glass layer; 123, phosphosilicon glass layer; 104, modification layer; 114, first modification layer; 124, second modification layer; 105, semiconductor layer; 115, first semiconductor layer; 125, second semiconductor layer; 40, back contact cell; 41, encapsulation film; 42, cover plate; 43, conductive strip. DETAILED DESCRIPTION

[0037] As known from the background, the manufacturing efficiency of back contact cells needs to be improved.

[0038] The embodiment of the present application provides a back contact cell and a manufacturing method thereof and a photovoltaic module. In the manufacturing method, in the step of forming a silicon glass layer, the mole percentage content of a doping element in the silicon glass layer is controlled to be 5-10%. On the one hand, the formed silicon glass layer has high compactness, so that the etching resistance of the silicon glass layer is improved in the subsequent step of taking the silicon glass layer as a mask layer, so that the doping layer and the medium layer that need to be reserved are prevented from being over-etched, thereby improving the yield of the finally manufactured back contact cell. On the other hand, the mole percentage content of the doping element in the silicon glass layer is moderate, which is beneficial to improving the forming rate of the silicon glass layer, thereby improving the manufacturing efficiency of the back contact cell. In addition, in the step of performing a patterning process on the doping layer and the medium layer, the silicon glass layer is directly taken as a mask layer, and an additional mask is not needed, which is beneficial to simplifying the manufacturing process of the back contact cell, thereby being beneficial to further improving the manufacturing efficiency of the back contact cell. In this way, the yield of the finally manufactured back contact cell is improved, and the manufacturing efficiency of the back contact cell is improved.

[0039] In the description of the embodiments of the present application, the technical terms "first", "second", and the like are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise explicitly and specifically limited.

[0040] In this document, referring to "embodiments" means that the specific features, structures or characteristics described in connection with the embodiments can be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily mean that the same embodiments are referred to, nor does it mean that independent or alternative embodiments are mutually exclusive or alternative to each other. The skilled person in the art explicitly and implicitly understands that the embodiments described herein can be combined with other embodiments.

[0041] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can mean that A exists, A and B exist, and B exists. In addition, the character " / " in this document generally represents a "or" relationship between the front and rear associated objects.

[0042] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0043] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0044] In the description of the embodiments of the present application, unless otherwise specified and limited, the technical terms "mounting", "connecting", "connecting", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0045] In the corresponding drawings of the embodiments of the present application, the thickness and area of the layer are exaggerated for better understanding and ease of description. When describing a component (such as a layer, film, region or substrate) on or on the surface of another component, the component can be "directly" on the surface of the other component, or a third component can exist between the two components. On the contrary, when describing a component on the surface of another component or a component surface forming or providing another component, it means that there is no third component between the two components. In addition, when a component is described as "formed substantially" on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on the edge of the entire surface.

[0046] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise stated, other components are not excluded and other components can also be further included. In addition, when a layer, film, region or plate and the like is referred to as "on / over" another component, it can be "directly on" another component (i.e. between the surface of another component and another component without other components), or another component can exist therebetween. In addition, when a layer, film, region, plate and the like is "directly on" another component, or when a layer, film, region, plate and the like is on the surface of another component, it means that no other component is located therebetween.

[0047] The terminology used in the description of the various described embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, the phrase "the component" is intended to mean both "the component" and "at least one of the components" unless otherwise indicated. In other words, the phrase "the component" is intended to mean "one or more of the components" or "one or more of the components." Also, as used in the description of the various embodiments, the phrase "coupled" means "connected, either directly or indirectly" unless specifically noted otherwise.

[0048] The embodiments of the present application will be described in detail with reference to the drawings, wherein the same or similar components are denoted by the same reference numerals, and therefore, the description will be given only with respect to the differences from the previous embodiments. However, it is to be understood that many details of the application can be made without departing from the spirit and scope of the application.

[0049] An embodiment of the present application provides a manufacturing method of a back contact cell. The manufacturing method of the back contact cell provided by an embodiment of the present application will be described in detail below with reference to the accompanying drawings.

[0050] In conjunction with reference to Figure 1 , and Figures 2 to 12 , the manufacturing method of the back contact cell at least includes the following steps:

[0051] S1: in conjunction with reference to Figure 2 , Figure 2 FIG. 1 is a partial cross-sectional schematic view of a substrate in a manufacturing method of a back contact cell provided by an embodiment of the present application. The manufacturing method of the back contact cell provided by an embodiment of the present application includes the following steps.

[0052] S2: in conjunction with reference to Figure 3 , or Figure 7 , a dielectric layer 101 is formed on the second surface 120.

[0053] S3: in conjunction with reference to Figures 4 to 5 , or in conjunction with reference to Figures 9 to 10 , a doped layer 102 and a silicon glass layer 103 are formed on a side of the dielectric layer 101 away from the substrate 100, the doped layer 102 and the silicon glass layer 103 both have a doping element, and the mole percentage content of the doping element in the silicon glass layer 103 is 5% to 10%.

[0054] S4: in conjunction with reference to Figure 5 , and Figure 7 , or in conjunction with reference to Figure 10 , and Figure 12 , the silicon glass layer 103 located on the first region 1201 or the second region 1202 is removed.

[0055] S5: continue in conjunction with reference to Figures 5 to 7or in combination with reference Figures 10 to 12 The etching treatment is performed on the remaining silicon glass layer 103 as a mask layer to remove the doped layer 102 and the medium layer 101 which are not covered by the mask layer.

[0056] wherein, Figure 1 A process flow diagram corresponding to the manufacturing method of the back contact battery provided by an embodiment of the present application; Figures 2 to 7 A partial cross-sectional schematic diagram corresponding to each step of the first kind in the manufacturing method of the back contact battery provided by an embodiment of the present application; Figures 8 to 12 A partial cross-sectional structural diagram corresponding to each step of the second kind in the manufacturing method of the back contact battery provided by an embodiment of the present application. It should be noted that the subsequent Figures 3 to 12 will be described in detail.

[0057] It is worth noting that by controlling the mole percentage content of the doped element in the silicon glass layer 103 formed in step S3 to be 5% to 10%, on the one hand, it is conducive to promoting the silicon glass layer 103 formed to have a higher compactness, so as to improve the etching resistance of the silicon glass layer 103 when the silicon glass layer 103 is used as a mask layer in the subsequent step S5, so as to avoid over-etching of the doped layer 102 and the medium layer 101 which need to be reserved, thereby improving the yield of the back contact battery finally manufactured; on the other hand, controlling the mole percentage content of the doped element in the silicon glass layer 103 formed to be moderate is conducive to improving the formation rate of the silicon glass layer 103 in step S3, thereby improving the manufacturing efficiency of the back contact battery; and on the other hand, in the step of patterning the doped layer 102 and the medium layer 101 in step S5, the silicon glass layer 103 can be directly used as a mask layer without the need for additional masks, which is conducive to simplifying the manufacturing process of the back contact battery, i.e. reducing the process of additionally preparing masks, reducing process time and reducing manufacturing cost, thereby being conducive to further improving the manufacturing efficiency of the back contact battery. Such multiple aspects cooperate to be conducive to improving the yield of the back contact battery finally manufactured while improving the manufacturing efficiency of the back contact battery.

[0058] The embodiments of the present application will be described in more detail below with reference to the accompanying drawings.

[0059] In some embodiments, the step of removing the silicon glass layer 103 can include: in combination with reference Figure 5 and Figure 6 , or in combination with reference Figure 10 and Figure 11 , performing laser treatment on the silicon glass layer 103 located on the first region 1201 or the second region 1202 to form a modified layer 104; in combination with reference Figure 6 and Figure 7 , or in combination with reference Figure 11 and Figure 12 , removing the modified layer 104 in the step of performing etching treatment.

[0060] Further, the following will be continued in combination with reference to Figure 6 and Figure 7 , or in combination with reference to Figure 11 and Figure 12 , in the step of performing etching treatment, the remaining silicon glass layer 103 is also used as a mask layer to perform etching treatment, so as to remove the doped layer 102 and the medium layer 101 covered by the modified layer 104. It is worth noting that, compared with the part of the silicon glass layer 103 which has not been treated by laser, the part of the silicon glass layer 103 which has been treated by laser, i.e. the modified layer 104, will be modified to a more loose structure and is more easily removed by subsequent etching treatment. In other words, compared with the silicon glass layer 103 which has not been treated by laser, the modified layer 104 is a more loose structure. In this way, not only can the patterning treatment of the doped layer 102 and the medium layer 101 be realized by means of the silicon glass layer 103, but also the laser power used in the step of laser treatment of the silicon glass layer 103 can be avoided to be too large, so as to avoid damage to the substrate 100 by laser.

[0061] It should be noted that, based on the different types of doped elements in the silicon glass layer 103, the subsequent laser treatment and etching treatment of the silicon glass layer 103 doped with different types of doped elements will be described in detail.

[0062] In other embodiments, the step of removing the silicon glass layer can also be: directly using laser to remove the silicon glass layer located on the first region or the second region.

[0063] In some embodiments, in combination with reference to Figures 4 to 5 , or in combination with reference to Figures 9 to 10 , the step of forming the doped layer 102 and the silicon glass layer 103 can include: in combination with reference to Figure 4 or Figure 9 , forming a semiconductor layer 105 on the side of the medium layer 101 away from the substrate 100; in combination with reference to Figure 4 and Figure 5 , or in combination with reference to Figure 9 and Figure 10 , performing a doping treatment on the semiconductor layer 105 to convert the semiconductor layer 105 into the doped layer 102, and forming the silicon glass layer 103 on the side of the doped layer 102 away from the substrate 100, and controlling the mole percentage content of the doped element in the silicon glass layer 103 to be 5% to 10%.

[0064] It is worth noting that in the step of preparing the doped layer 102 and the silicon glass layer 103, the doped layer 102 and the silicon glass layer 103 are formed synchronously. In order to form the doped layer 102 with the doping element, the semiconductor layer 105 needs to be subjected to a doping treatment. In the step-by-step progress of the doping treatment, not only the doping element diffuses into the semiconductor layer 105 to convert the semiconductor layer 105 into the doped layer 102, but also the silicon glass layer 103 is eventually formed on the side of the doped layer 102 away from the substrate 100 based on an oxidation reaction.

[0065] In some cases, the material of the semiconductor layer 105 can be a semiconductor material, and the doped layer 102 can be a semiconductor material including the doping element. In one example, the material of the semiconductor layer 105 is silicon, the material of the doped layer 102 is silicon material including the doping element, and the material of the silicon glass layer 103 formed based on the doping treatment is silicon oxide including the doping element.

[0066] The manufacturing method of the back contact cell is described in detail below by taking boron as an example of the doping element.

[0067] In some embodiments, referring to Figures 3 to 4 , the medium layer 101 includes a first medium layer 111, the semiconductor layer 105 includes a first semiconductor layer 115, and the doping element includes boron; in combination with reference to Figure 4 and Figure 5 , the doped layer 102 formed after the doping treatment includes a first doped layer 112, and the silicon glass layer 103 includes a borosilicon glass layer 113; in the borosilicon glass layer 113, the molar percentage content of boron in the silicon oxide is 5% to 10%. Based on this, in some cases, the step of removing the silicon glass layer 103 located on the first region 1201 or the second region 1202 in step S4 can include the following steps: in combination with reference to Figure 5 and Figure 6 , performing laser treatment on the borosilicon glass layer 113 located on the second region 1202 to convert the borosilicon glass layer 113 located on the second region 1202 into a first modified layer 114; in combination with reference to Figure 6 and Figure 7 , removing the first modified layer 114 in the step of performing etching treatment.

[0068] wherein, Figure 3 is a partial cross-sectional schematic view of a manufacturing method of a back contact cell provided in an embodiment of the present application after forming a first medium layer; Figure 4 is a partial cross-sectional schematic view of a manufacturing method of a back contact cell provided in an embodiment of the present application after forming a first semiconductor layer; Figure 5 is a partial cross-sectional schematic view of a manufacturing method of a back contact cell provided in an embodiment of the present application after performing a doping treatment; Figure 6A partial cross-sectional view of a back contact cell after laser processing in a method for manufacturing a back contact cell according to an embodiment of the present application; Figure 7 A partial cross-sectional view of a back contact cell after etching processing in a method for manufacturing a back contact cell according to an embodiment of the present application. Further, in the step of etching processing, the borosilicate glass layer 113 remaining on the first region 1201 is used as a mask layer, and the first doped layer 112 and the first dielectric layer 111 covered by the first modification layer 114 on the second region 1202 are removed.

[0069] It is worth noting that, wherein the first doped layer 112 and the first dielectric layer 111 remaining on the first region 1201 together constitute a first passivation contact structure, which provides a good interface passivation for the first region 1201. In this way, on the one hand, the first dielectric layer 111 can realize the selective transmission of carriers to reduce the recombination current; on the other hand, the lateral transmission characteristics of the first doped layer 112 reduce the series resistance, and the above two characteristics together improve the open-circuit voltage, the fill factor, and the photoelectric conversion efficiency of the back contact cell.

[0070] In some cases, the molar percentage content of boron in the silicon oxide in the borosilicate glass layer 113 can be measured by ICP-OES (Inductively Coupled Plasma optical emission spectrometry). The working principle of ICP-OES is roughly as follows: the boron atoms in the selected sample of the borosilicate glass layer 113 are excited by plasma, and the quantification is performed by detecting the characteristic spectral line intensity. The detection steps of the selected sample of the borosilicate glass layer 113 are roughly as follows: dissolve and dilute the selected sample of the borosilicate glass layer 113 to a suitable concentration; use the ICP-OES instrument to measure the emission spectrum intensity of boron; calculate the molar percentage content of boron in the sample by the standard curve.

[0071] In some cases, referring to Figure 3 The first dielectric layer 111 can be formed by an LPCVD (Low Pressure Chemical Vapor Deposition) process. In some examples, the process temperature for forming the first dielectric layer 111 is 500-650°C, for example, it can be 510°C, 520°C, 530°C, 540°C, 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, or 640°C, etc. It should be noted that the present application does not make too many restrictions on the preparation process of the first dielectric layer 111, and in actual application, other processes can also be used to prepare the first dielectric layer.

[0072] In some cases, the first dielectric layer 111 can be regarded as a tunneling oxide layer, and the material of the first dielectric layer 111 includes at least one of silicon oxide, silicon carbide, silicon nitride, and silicon oxynitride. In some examples, the thickness of the first dielectric layer 111 along the first direction X can be 1 nm to 2 nm, for example, 1.1 nm, 1.2 nm, 1.3 nm, 1.4 nm, 1.5 nm, 1.6 nm, 1.7 nm, 1.8 nm, or 1.9 nm, etc.

[0073] In some cases, the first semiconductor layer 115 can be formed by an LPCVD process. Figure 4 In some examples, the process temperature for forming the first semiconductor layer 115 is 500°C to 650°C. It should be noted that the preparation process of the first semiconductor layer 115 is not limited in the embodiment of the present application, and other processes can also be used to prepare the first semiconductor layer in actual applications.

[0074] In some cases, the material of the first semiconductor layer 115 can be silicon, and the first semiconductor layer 115 can include at least one of amorphous silicon and polycrystalline silicon, in other words, the morphology of silicon in the first semiconductor layer 115 is variable. In some examples, the thickness of the first semiconductor layer 115 along the first direction X can be 50 nm to 500 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, or 450 nm, etc.

[0075] In some cases, the thickness of the borosilicate glass layer 113 along the first direction X can be 20 nm to 100 nm, for example, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, or 90 nm, etc. It should be noted that the first direction X is the thickness direction of the substrate 100.

[0076] In some cases, the molar percentage content of boron in the silicon oxide in the borosilicate glass layer 113 can be 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, or 9.5%, etc.

[0077] In some cases, the doping process includes: first performing a first extension treatment, and then performing a first junction pushing treatment. The step of performing the first extension treatment can include: placing the substrate 100 after forming the first semiconductor layer 115 into a reaction chamber, and introducing boron trichloride into the reaction chamber. The step of performing the first junction pushing treatment can include: first performing a first oxygen-containing junction pushing treatment, introducing a mixed gas of boron trichloride and oxygen into the reaction chamber; and then performing a first oxygen-free junction pushing treatment, introducing boron trichloride into the reaction chamber.

[0078] It is worth noting that, by means of the cooperation of the first oxygen push processing and the first oxygen-free push processing, on the one hand, the molar percentage content of boron in silicon oxide in the borosilicate glass layer 113 formed finally is controlled in the range of 5% to 10%, so as to ensure the compactness of the borosilicate glass layer 113 while improving the growth rate of the borosilicate glass layer 113; on the other hand, the concentration of boron diffused into the first semiconductor layer 115 is controlled, so as to ensure that the doping concentration of boron in the first doped layer 112 is moderate.

[0079] In some examples, the doping concentration of boron in the first doped layer 112 can be 8×10 18 atom / cm 3 , for example, can be 9×10 20 atom / cm 3 , 1×10 18 atom / cm 3 , 3×10 19 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 19 atom / cm 3 , 3×10 20 atom / cm 3 , 5×10 20 atom / cm 3 , 6×10 20 atom / cm 3 , or 8×10 20 atom / cm 3 , etc.

[0080] In some examples, the gas flow of boron trichloride introduced into the reaction chamber can be 50sccm to 200sccm, for example, can be 60sccm, 70sccm, 80sccm, 90sccm, 100sccm, 110sccm, 120sccm, 130sccm, 140sccm, 150sccm, 160sccm, 170sccm, 180sccm or 190sccm, etc.

[0081] It should be noted that, whether in the step of performing the first diffusion processing or in the step of performing the push processing, the gas flow of boron trichloride introduced into the reaction chamber can be designed in the range of 50sccm to 200sccm.

[0082] In some examples, a ratio of a processing time length of the first aerobic knotting process to a processing time length of the first anaerobic knotting process can be 1:20-1:3, for example, can be 0.1, 0.15, 0.2, 0.25, or 0.3, etc.

[0083] It should be noted that "anaerobic" in the first anaerobic knotting process refers to not introducing oxygen into the reaction chamber in this stage. In actual application, if required in this stage, other gases containing oxygen elements can be introduced in this stage.

[0084] It is worth noting that the molar percentage content of boron in silicon oxide in the finally formed borosilicate glass layer 113 is mainly affected by the gas flow of boron trichloride and the ratio of the processing time length of the first aerobic knotting process to the processing time length of the first anaerobic knotting process. Based on this, the gas flow of boron trichloride is designed to be 50-200sccm, and the ratio of the processing time length of the first aerobic knotting process to the processing time length of the first anaerobic knotting process is designed to be 1:20-1:3, which are both conducive to controlling the molar percentage content of boron in silicon oxide in the finally formed borosilicate glass layer 113 within the range of 5%-10%.

[0085] In some examples, in the step of performing the first aerobic knotting process, the ratio of the gas flow of oxygen to the gas flow of boron trichloride can be 2-10, for example, can be 3, 4, 5, 6, 7, 8, or 9, etc.

[0086] In some examples, the process temperature used in the first expansion process is 800-900°C, for example, can be 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 870°C, 880°C, or 890°C, etc.

[0087] In some examples, the knotting temperature used in the first knotting process is 900-1050°C, for example, can be 910°C, 920°C, 930°C, 940°C, 950°C, 960°C, 970°C, 980°C, 990°C, 1000°C, 1010°C, 1020°C, 1030°C, or 1040°C, etc. It should be noted that the knotting temperature used in the first aerobic knotting process and the first anaerobic knotting process can be 900-1050°C.

[0088] The manufacturing method of the back contact cell is described in detail below taking phosphorus as an example of the doping element.

[0089] In some embodiments, referring to Figures 8 to 9 , the medium layer 101 includes a second medium layer 121, the semiconductor layer 105 includes a second semiconductor layer 125, and the doping element includes phosphorus; in combination with referring to Figure 9 and Figure 10The doped layer 102 formed after the doping treatment includes a second doped layer 122, and the silicon glass layer 103 includes a phosphor silicon glass layer 123. In the phosphor silicon glass layer 123, the molar percentage content of phosphorus in silicon oxide is 5% to 10%.

[0090] Based on this, in some cases, the step of removing the silicon glass layer 103 located on the first region 1201 or the second region 1202 in step S4 can include the following steps: in combination with reference to Figure 10 and Figure 11 performing laser treatment on the phosphor silicon glass layer 123 located on the first region 1201 to convert the phosphor silicon glass layer 123 located on the first region 1201 into a second modified layer 124; in combination with reference to Figure 11 and Figure 12 removing the second modified layer 124 in the step of performing etching treatment.

[0091] wherein, Figure 8 FIG. 4 is a partial cross-sectional schematic view of a back contact battery manufacturing method provided by an embodiment of the present application after forming a second medium layer; Figure 9 FIG. 5 is a partial cross-sectional schematic view of a back contact battery manufacturing method provided by an embodiment of the present application after forming a second semiconductor layer; Figure 10 FIG. 6 is another partial cross-sectional schematic view of a back contact battery manufacturing method provided by an embodiment of the present application after performing doping treatment; Figure 11 FIG. 7 is another partial cross-sectional schematic view of a back contact battery manufacturing method provided by an embodiment of the present application after performing laser treatment; Figure 12 FIG. 8 is another partial cross-sectional schematic view of a back contact battery manufacturing method provided by an embodiment of the present application after performing etching treatment.

[0092] Further, in the step of performing etching treatment, the phosphor silicon glass layer 123 remaining on the second region 1202 is also used as a mask layer to remove the second doped layer 122 and the second medium layer 121 covered by the second modified layer 124 located on the first region 1201. It is worth noting that the second doped layer 122 and the second medium layer 121 remaining on the second region 1202 together constitute a second passivation contact structure, which provides good interface passivation for the second region 1202. In this way, on the one hand, the second medium layer 121 can realize selective transmission of carriers to reduce recombination current; on the other hand, the lateral transmission characteristics of the second doped layer 122 reduce the series resistance, and the above two characteristics together improve the open-circuit voltage, the fill factor, and the photoelectric conversion efficiency of the back contact battery.

[0093] In some cases, the molar percentage content of phosphorus in silicon oxide in the phosphosilicate glass layer 123 can also be measured by ICP-OES. The working principle of ICP-OES is roughly as follows: the phosphorus atoms in the selected sample of the phosphosilicate glass layer 123 are excited by plasma, and the quantification is performed by detecting the characteristic spectral line intensity. The detection steps of the selected sample of the phosphosilicate glass layer 123 are roughly as follows: the selected sample of the phosphosilicate glass layer 123 is dissolved and diluted to a suitable concentration; the emission spectrum intensity of phosphorus is measured by using the ICP-OES instrument; and the molar percentage content of phosphorus in the sample is calculated by the standard curve.

[0094] It should be noted that the second dielectric layer 121 can also be regarded as a tunnel oxide layer, and the same or corresponding parts of the second dielectric layer 121 and the first dielectric layer 111 will not be repeated here.

[0095] In some cases, the material of the second semiconductor layer 125 can also be silicon, and the second semiconductor layer 125 can include at least one of amorphous silicon and polycrystalline silicon, in other words, the morphology of silicon in the second semiconductor layer 125 is variable. It should be noted that the same or corresponding parts of the second semiconductor layer 125 and the first semiconductor layer 115 will not be repeated here.

[0096] In some cases, along the first direction X, the thickness of the phosphosilicate glass layer 123 can be 50-100 nm, for example, 60 nm, 70 nm, 80 nm, or 90 nm, etc. It should be noted that the first direction X is the thickness direction of the substrate 100.

[0097] In some cases, the molar percentage content of phosphorus in silicon oxide in the phosphosilicate glass layer 123 can be 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, or 9.5%, etc.

[0098] In some cases, the step of performing the doping treatment includes: first performing a second extension treatment, and then performing a second push junction treatment; the step of performing the second extension treatment can include: placing the substrate 100 after forming the second semiconductor layer 125 into a reaction chamber, and introducing nitrogen gas carrying phosphorus oxychloride into the reaction chamber; the step of performing the second push junction treatment can include: first performing a second oxygen-containing push junction treatment, introducing a mixed gas carrying nitrogen gas and oxygen gas carrying phosphorus oxychloride into the reaction chamber; and then performing a second oxygen-free push junction treatment, introducing nitrogen gas carrying phosphorus oxychloride into the reaction chamber.

[0099] Notably, with the cooperation of the second oxygen push process and the second oxygen-free push process, on the one hand, the molar percentage content of phosphorus in silicon oxide in the phosphosilicate glass layer 123 formed finally is controlled in the range of 5% to 10%, so as to ensure the compactness of the phosphosilicate glass layer 123 while improving the growth rate of the phosphosilicate glass layer 123; on the other hand, the concentration of phosphorus diffused into the second semiconductor layer 125 is controlled, so as to ensure that the doping concentration of phosphorus in the second doped layer 122 is moderate.

[0100] In some examples, the doping concentration of phosphorus in the second doped layer 122 can be 1×10 19 atom / cm 3 , for example, can be 3×10 21 atom / cm 3 , 5×10 19 atom / cm 3 , 6×10 19 atom / cm 3 , 8×10 19 atom / cm 3 , 1×10 19 atom / cm 3 , 3×10 20 atom / cm 3 , 5×10 20 atom / cm 3 , 6×10 20 atom / cm 3 , 8×10 20 atom / cm 3 , 1×10 20 atom / cm 3 , etc.

[0101] In some examples, the gas flow of nitrogen gas carrying phosphorus oxychloride introduced into the reaction chamber can be in the range of 800sccm to 2000sccm, for example, can be 900sccm, 1000sccm, 1100sccm, 1200sccm, 1300sccm, 1400sccm, 1500sccm, 1600sccm, 1700sccm, 1800sccm or 1900sccm, etc.

[0102] It should be noted that, whether in the second diffusion process step or in the push process step, the gas flow of nitrogen gas carrying phosphorus oxychloride introduced into the reaction chamber can be designed in the range of 800sccm to 2000sccm.

[0103] In some examples, the ratio of the processing time length of the second aerobic bunching process to the processing time length of the second anaerobic bunching process is 1:10-1:2, for example, can be 0.15, 0.2, 0.25, 0.3, 0.35, 0.4 or 0.45, etc.

[0104] It should be noted that "anaerobic" in the second anaerobic bunching process refers to that no oxygen is introduced into the reaction chamber in this stage, and other gases containing oxygen elements, such as nitrogen carrying phosphorus oxychloride, can be introduced.

[0105] It is worth noting that the molar percentage content of phosphorus in silicon oxide in the finally formed phosphosilicate glass layer 123 is mainly affected by the flow rate of phosphorus oxychloride and the ratio of the processing time length of the second aerobic bunching process to the processing time length of the second anaerobic bunching process. Based on this, the gas flow rate of nitrogen carrying phosphorus oxychloride is designed to be 800-2000sccm, and the ratio of the processing time length of the second aerobic bunching process to the processing time length of the second anaerobic bunching process is designed to be 1:10-1:2, which is beneficial to control the molar percentage content of phosphorus in silicon oxide in the finally formed phosphosilicate glass layer 123 within the range of 5%-10%.

[0106] In some examples, in the step of performing the second aerobic bunching process, the ratio of the gas flow rate of oxygen to the gas flow rate of nitrogen carrying phosphorus oxychloride is 0.5-2, for example, can be 0.6, 0.7, 0.8, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8 or 1.9, etc.

[0107] In some examples, in the step of performing the second bunching process, the process temperature adopted by the second bunching process is 800-900℃, for example, can be 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃ or 890℃, etc.

[0108] In some examples, the bunching temperature adopted by the second bunching process is 880-990℃, for example, can be 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃ or 980℃, etc. It should be noted that the bunching temperature adopted by the second aerobic bunching process and the second anaerobic bunching process can be 900-1050℃.

[0109] In some examples, the step of introducing the nitrogen gas carrying the phosphorus oxychloride into the reaction chamber can include: providing a constant-temperature tank containing liquid phosphorus oxychloride outside the reaction chamber, the constant-temperature tank and the reaction chamber being connected by a pipeline for gas flow; introducing nitrogen gas into the constant-temperature tank, and the nitrogen gas carrying the phosphorus oxychloride overflowing from the liquid phosphorus oxychloride is introduced into the reaction chamber through the pipeline. It is worth noting that the normal state of phosphorus oxychloride is liquid, and the liquid phosphorus oxychloride needs to be processed to provide phosphorus oxychloride into the reaction chamber by means of nitrogen gas.

[0110] In some examples, the temperature of the constant-temperature tank can be 20-25℃, for example, it can be 21℃, 22℃, 23℃ or 24℃, etc.

[0111] In some examples, the proportion of phosphorus oxychloride in the nitrogen gas carrying the phosphorus oxychloride can be 5%-15%, for example, it can be 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14%, etc.

[0112] It is worth noting that in order to control the proportion of phosphorus oxychloride in the nitrogen gas carrying the phosphorus oxychloride, the temperature of the constant-temperature tank can be adjusted to control the content of phosphorus oxychloride carried by nitrogen gas in a known unit gas flow, so as to realize the control of the molar percentage content of phosphorus in the finally formed phosphorus-silicon glass layer 123.

[0113] It should be noted that the above steps of forming the first doped layer 112 and the first dielectric layer 111 by means of the boron-silicon glass layer 113 with a molar percentage content of boron of 5%-10%, and the above steps of forming the second doped layer 122 and the second dielectric layer 121 by means of the phosphorus-silicon glass layer 123 with a molar percentage content of phosphorus of 5%-10% can be applied to the manufacturing method of the same back contact cell, and finally form a TBC cell (TOPCon Back Contact, which refers to a cross-passivation back contact cell). Moreover, the order of the steps of forming the first doped layer 112 and the first dielectric layer 111 and the steps of forming the second doped layer 122 and the second dielectric layer 121 in the manufacturing method of the back contact cell provided by the embodiment of the present application is not limited.

[0114] In practical applications, in one embodiment of the manufacturing method of the back contact battery provided in this application, based on the formation of a first doped layer and a first dielectric layer using a borosilicate glass layer with a boron molar percentage content of 5% to 10%, a second dielectric layer consisting of at least one of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon can be formed on the second region, as well as a second doped layer doped with an N-type dopant element, such as phosphorus, to ultimately form an HTBC battery; or, based on the formation of a second doped layer and a second dielectric layer using a phosphorus-silicon glass layer with a phosphorus molar percentage content of 5% to 10%, a first dielectric layer consisting of at least one of amorphous silicon, microcrystalline silicon, and nanocrystalline silicon can be formed on the first region, as well as a first doped layer doped with a P-type dopant element, such as boron, to ultimately form an HTBC battery.

[0115] Among them, HTBC cells are heterojunction tunnel oxide passivated contact hybrid passivated back contact photovoltaic cells (abbreviated as HTBC).

[0116] In some embodiments, reference Figure 2 The step of providing substrate 100 includes: providing an initial substrate and performing alkaline polishing on the initial substrate to remove impurities on the surface of the initial substrate, and forming a substrate 100 with a flat surface, which is beneficial for subsequent preparation of dielectric layer 101 and doped layer 102.

[0117] In some cases, the reflectivity of the second surface 120 of the substrate 100 after alkali polishing is greater than or equal to 40%; the size of the base on the second surface 120 can be 10μm to 50μm, for example, it can be 15μm, 20μm, 25μm, 30μm, 35μm, 40μm or 45μm, etc.

[0118] In summary, by controlling the mole percentage content of the doping element in the formed silicon glass layer 103 in step S3 to be 5% to 10%, on the one hand, it is beneficial to promote the formed silicon glass layer 103 to have higher compactness, so as to improve the etching resistance of the silicon glass layer 103 in the subsequent step S5, so as to avoid the over-etching of the doping layer 102 and the medium layer 101 which need to be reserved, thereby improving the yield of the finally manufactured back contact cell; on the other hand, controlling the mole percentage content of the doping element in the formed silicon glass layer 103 to be moderate is beneficial to improve the formation rate of the silicon glass layer 103 in step S3, thereby improving the manufacturing efficiency of the back contact cell; and on the other hand, in the step of patterning the doping layer 102 and the medium layer 101 in step S5, the silicon glass layer 103 can be directly used as a mask layer without the need for additional masks, which is beneficial to simplify the manufacturing process of the back contact cell, thereby further improving the manufacturing efficiency of the back contact cell. Such multiple aspects cooperate to improve the yield of the finally manufactured back contact cell while improving the manufacturing efficiency of the back contact cell.

[0119] The following are specific embodiments of the manufacturing method of the back contact cell provided by an embodiment of the present application, as well as expected related comparative examples:

[0120] Embodiment 1

[0121] The back contact cell 1 is prepared by the following steps:

[0122] (1) An N-type monocrystalline silicon wafer is selected, the resistivity of the N-type monocrystalline silicon wafer is about 0.5 ohmm to 10 ohmm, and the thickness of the N-type monocrystalline silicon wafer in the first direction X is about 130 μm; the N-type monocrystalline silicon wafer is subjected to alkali polishing treatment, for example, a tank-type texturing device is used to polish the first surface 110 and the second surface 120 of the substrate 100 to obtain the substrate 100.

[0123] Specifically, the damaged layer on the surface of the N-type monocrystalline silicon wafer is first removed in a mixed solution including potassium hydroxide and hydrogen peroxide, and then alkali polishing is performed in a sodium hydroxide solution or a potassium hydroxide solution to form a substrate 100 including a flat tower base morphology on the surface, the size of the tower base is about 15 μm, and the reflectivity of the tower base morphology is about 40%.

[0124] (2) A tunnel oxide layer and an intrinsic amorphous silicon layer are prepared on the second surface 120 using an LPCVD process, the thickness of the tunnel oxide layer is 1.5 nm, and the thickness of the intrinsic amorphous silicon layer is 300 nm, and the process temperature of the LPCVD process is 560°C.

[0125] (3) High-temperature boron diffusion is performed on the intrinsic amorphous silicon layer using a tube diffusion device, the intrinsic amorphous silicon layer is converted into a polycrystalline silicon layer after boron diffusion, and the doping concentration of boron in the polycrystalline silicon layer is 6×10 19atom / cm 3 The thickness of the borosilicate glass layer (BSG) formed after boron diffusion is 60 nm. In the BSG, the molar percentage content of boron in the silicon oxide is controlled at 8%. The deposition temperature of the boron-doped source layer formed during the boron diffusion process is 850°C. The process temperature used in the push joint treatment is 960°C. The flow rate of boron trichloride introduced during the boron diffusion process is 90 sccm. The ratio of the gas flow rate of oxygen to the gas flow rate of boron trichloride in the first oxygen-containing push joint treatment is 5.

[0126] (4) Laser processing is performed on the BSG located on one of the first region and the second region to convert the BSG located on one of the first region and the second region into a modified layer.

[0127] (5) Etching processing is performed on the BSG remaining on the other one of the first region and the second region as a mask layer to remove the modified layer, and remove the tunnel oxide layer and the doped polysilicon layer covered by the modified layer.

[0128] (6) Subsequent steps can complete the manufacturing of the back contact cell according to the existing process flow, which will not be described in detail here, to finally form the back contact cell 1.

[0129] Comparative Example 1

[0130] The back contact cell 2 is prepared by the following steps:

[0131] Steps (1) to (2) are the same as those of Example 1, which will not be described here.

[0132] (3) High-temperature boron diffusion is performed on the intrinsic amorphous silicon layer by using a tube diffusion device. The intrinsic amorphous silicon layer is converted into a polysilicon layer after boron diffusion, and the doping concentration of boron in the polysilicon layer is 6 x 10 19 atom / cm 3 .

[0133] (4) A silicon nitride film is deposited on the first region 1201. Specifically, a silicon nitride film can be deposited on the first region 1201 as a mask by using a PECVD process. The thickness of the silicon nitride film is 60 nm.

[0134] (5) Subsequent steps can complete the manufacturing of the back contact cell according to the existing process flow, which will not be described in detail here, to finally form the back contact cell 2.

[0135] Comparative Example 2

[0136] The back contact cell 3 is prepared by the following steps:

[0137] Steps (1) to (2) are the same as those of Example 1, which will not be described here.

[0138] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion by using a tube diffusion device. After boron diffusion, the intrinsic amorphous silicon layer is converted into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 3×10 19 atom / cm 3 The thickness of the borosilicate glass layer, i.e., BSG, formed after boron diffusion is 60 nm, and the molar percentage content of boron in the silicon oxide in the BSG is controlled to be less than 5%.

[0139] Steps (4) to (5) are the same as those in Example 1, and will not be described herein again.

[0140] (6) Subsequent steps can be completed according to the existing process flow to manufacture the back contact cell, and will not be described herein again. Finally, the back contact cell 3 is formed.

[0141] Comparative Example 3

[0142] The back contact cell is prepared by the following steps:

[0143] Steps (1) to (2) are the same as those in Example 1, and will not be described herein again.

[0144] (3) The intrinsic amorphous silicon layer is subjected to high-temperature boron diffusion by using a tube diffusion device. After boron diffusion, the intrinsic amorphous silicon layer is converted into a polycrystalline silicon layer, and the boron doping concentration in the polycrystalline silicon layer is 8×10 19 atom / cm 3 The thickness of the borosilicate glass layer, i.e., BSG, formed after boron diffusion is 60 nm, and the molar percentage content of boron in the silicon oxide in the BSG is controlled to be greater than 10%.

[0145] Steps (4) to (5) are the same as those in Example 1, and will not be described herein again.

[0146] (6) Subsequent steps can be completed according to the existing process flow to manufacture the back contact cell, and will not be described herein again. It should be noted that, since the molar percentage content of boron in the BSG in Comparative Example 3 is greater than 10%, the final product cell cannot be formed. Therefore, there is no product cell corresponding to Comparative Example 3 in Table 1 provided below.

[0147] Table 1 is the photovoltaic index corresponding to the back contact cell 1, the back contact cell 2 and the back contact cell 3

[0148]

[0149] Note: VOC represents open-circuit voltage, Isc represents short-circuit current, FF represents fill factor, and EFF represents photoelectric conversion efficiency.

[0150] From the experimental results, the BSG formed in the manufacturing method of the back contact cell provided by the embodiment of the present application is used as a mask, and the mole percentage content of boron in the BSG is controlled at 8%, the photovoltaic index of the finished product cell, i.e. the back contact cell 1, is basically the same as that of the back contact cell 2 formed by using the silicon nitride film as a mask in the comparative example 1, but the manufacturing method of the back contact cell provided by the embodiment of the present application uses the BSG formed in the preparation process as a mask, which reduces the deposition step of the silicon nitride mask, for example, about 60 min of process time is saved, and the manufacturing cost is also reduced, for example, the manufacturing cost of each back contact cell 1 can be saved by about 1 fen.

[0151] The comparative example 2 also uses the BSG formed in the preparation process as a mask, but the mole percentage content of boron in the BSG is less than 5% in the comparative example 2, which leads to a lower doping concentration of boron in the boron-doped polysilicon layer after boron diffusion, and the growth rate of the BSG is slower due to the lower mole percentage content of boron in the BSG, which leads to a longer process time of 45 min than that of the embodiment 1. Moreover, compared with the back contact cell 1 formed in the embodiment 1, the open circuit voltage, the short circuit current, the fill factor and the photoelectric conversion efficiency of the back contact cell 3 formed in the comparative example 2 are all reduced, and the fill factor of the back contact cell 3 formed in the comparative example 2 is greatly reduced, and the photoelectric conversion efficiency is about 0.17% lower than that of the back contact cell 1 formed in the embodiment 1.

[0152] The comparative example 3 also uses the BSG formed in the preparation process as a mask, but the mole percentage content of boron in the BSG is greater than 10% in the comparative example 2, which leads to a weak etching resistance of the BSG, so that the BSG cannot protect the tunnel oxide layer and the doped polysilicon layer located below the BSG in the process of preparing the back contact cell, and the finished product cell cannot be formed.

[0153] Another embodiment of the present application further provides a back contact cell formed by the manufacturing method of the back contact cell provided by the foregoing embodiments. The back contact cell provided by another embodiment of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as the foregoing embodiments will not be described herein.

[0154] The back contact cell includes the back contact cell formed by the manufacturing method of the back contact cell provided by the foregoing embodiments.

[0155] Still another embodiment of the present application further provides a photovoltaic module for converting received light energy into electrical energy. The photovoltaic module provided by still another embodiment of the present application will be described in detail below with reference to the accompanying drawings. It should be noted that the same or corresponding parts as the foregoing embodiments will not be described herein.

[0156] With reference to Figure 13 and Figure 14 , the photovoltaic module comprises: a cell string formed by connecting a plurality of back contact cells 40 formed by the manufacturing method of the back contact cell provided in the foregoing embodiments, or formed by connecting a plurality of back contact cells 40 provided in the foregoing embodiments; an encapsulation film 41 for covering the surface of the cell string; and a cover plate 42 for covering the surface of the encapsulation film 41 away from the cell string.

[0157] wherein, Figure 13 is a partial perspective view of a cell string in a photovoltaic module provided in another embodiment of the present application; Figure 14 is a partial cross-sectional view of a photovoltaic module provided in another embodiment of the present application.

[0158] In some embodiments, the back contact cells 40 are electrically connected in the form of a whole piece or multiple pieces to form a plurality of cell strings, and the plurality of cell strings are electrically connected in series and / or in parallel. The back contact cells 40 can be whole piece cells or sliced cells, where a sliced cell refers to a cell formed by cutting a whole piece cell.

[0159] In some embodiments, with reference to Figure 13 and Figure 14 , the plurality of back contact cells 40 can be electrically connected by a conductive ribbon 43. Figure 13 and Figure 14 Only the positional relationship between two back contact cells 40 is shown, i.e., the side of each back contact cell 40 with an electrode is arranged toward the same side, so that the conductive ribbon 43 connects two adjacent back contact cells 40 on the same side. In other embodiments, the back contact cells can also be arranged such that the electrodes of two adjacent back contact cells are located on different sides, and the conductive ribbon connects two adjacent back contact cells on different sides.

[0160] In some embodiments, the encapsulation film 41 comprises a first encapsulation layer covering one of the front side or the back side of the back contact cell 40, and a second encapsulation layer covering the other of the front side or the back side of the back contact cell 40. Specifically, at least one of the first encapsulation layer or the second encapsulation layer can be an organic encapsulation film such as a polyvinyl butyral (PVB) film, an ethylene-vinyl acetate (EVA) film, a polyolefin elastomer (POE) film, or a polyethylene terephthalate (PET) film, or at least one of the first encapsulation layer or the second encapsulation layer can also be an EP film, an EPE film, or a PVP film. The EP film refers to a co-extrusion film formed by stacking an EVA film and a POE film, the EPE film refers to a co-extrusion film formed by stacking an EVA film, a POE film, and an EVA film in sequence, and the PVP film refers to a co-extrusion film formed by stacking a POE film, an EVA film, and a POE film in sequence. The co-extrusion film can be prepared by extruding one or more raw materials onto another film that has been prepared, or by bonding different types of films to each other during film processing.

[0161] In some cases, the first encapsulation layer and the second encapsulation layer have a boundary before lamination, and after lamination, the photovoltaic module is formed without the concept of the first encapsulation layer and the second encapsulation layer, i.e., the first encapsulation layer and the second encapsulation layer have formed an integral encapsulation film 41.

[0162] In some embodiments, the cover plate 42 can be a glass cover plate, a plastic cover plate, or the like, which has a light-transmitting function. Specifically, the surface of the cover plate 42 facing the encapsulation film 41 can be a concave-convex surface or a suede surface comprising a plurality of convex structures, thereby increasing the utilization rate of incident light. The cover plate 42 comprises a first cover plate opposite the first encapsulation layer and a second cover plate opposite the second encapsulation layer.

[0163] It is to be understood that the above-described embodiments are merely illustrative of the principles of the application and that numerous and varied embodiments can be devised by those skilled in the art without departing from the spirit and scope of the application. Any variations of the embodiments of the application, falling within the scope of the claims, should be covered by the scope of the application.

Claims

1. A method for manufacturing a back-contact battery, characterized in that, include: A substrate is provided, the substrate having a first surface and a second surface opposite each other along a first direction, the second surface having a first region and a second region alternately arranged along a second direction; A dielectric layer is formed on the second surface; A semiconductor layer is formed on the side of the dielectric layer away from the substrate; The semiconductor layer is doped to transform it into a doped layer, and a silicon glass layer is formed on the side of the doped layer away from the substrate. Both the doped layer and the silicon glass layer have doping elements. The semiconductor layer includes a first semiconductor layer, the doping element includes boron, the doped layer includes a first doped layer, and the silicon glass layer includes a borosilicate glass layer. The doping process includes: performing a first broadening process, placing the substrate after forming the first semiconductor layer into a reaction chamber, and introducing boron trichloride into the reaction chamber; performing a first oxygen-enriched bonding process, introducing a mixture of boron trichloride and oxygen into the reaction chamber; and performing a first oxygen-free bonding process, introducing boron trichloride into the reaction chamber to control the molar percentage content of boron in the silicon oxide of the borosilicate glass layer to be 5%~10%. Alternatively, the semiconductor layer includes a second semiconductor layer, the doping element includes phosphorus, the doped layer includes a second doped layer, and the silicon glass layer includes a phosphosilicate glass layer; the doping process includes: performing a second diffusion process, placing the substrate after forming the second semiconductor layer into a reaction chamber, and introducing nitrogen gas carrying phosphorus oxychloride into the reaction chamber; performing a second oxygen-containing push-junction process, introducing a mixture of nitrogen gas carrying phosphorus oxychloride and oxygen gas into the reaction chamber; and performing a second oxygen-free push-junction process, introducing nitrogen gas carrying phosphorus oxychloride into the reaction chamber, so as to control the molar percentage content of phosphorus in silicon oxide in the phosphosilicate glass layer to be 5%~10%; Remove the silicon glass layer in the first region or the silicon glass layer in the second region; The remaining silicon glass layer is used as a mask layer for etching to remove the doped layer and the dielectric layer that are not covered by the mask layer.

2. The method for manufacturing a back contact battery according to claim 1, characterized in that, The flow rate of boron trichloride gas introduced into the reaction chamber is 50 sccm to 200 sccm; and / or, the ratio of the treatment time of the first aerobic push-junction treatment to the treatment time of the first anaerobic push-junction treatment is 1:20 to 1:

3.

3. The method for manufacturing a back contact battery according to claim 1 or 2, characterized in that, In the first aerobic bridging process, the ratio of oxygen flow rate to boron trichloride flow rate is 2 to 10.

4. The method for manufacturing a back contact battery according to claim 1, characterized in that, The process temperature used in the first expansion treatment is 800℃~900℃; and / or, the first aerobic push-bonding treatment and the first oxygen-free push-bonding treatment constitute the first push-bonding treatment, and the push-bonding temperature used in the first push-bonding treatment is 900℃~1050℃.

5. The method for manufacturing a back contact battery according to claim 1, characterized in that, The step of removing the silicon glass layer includes: laser processing the silicon glass layer located on the first region or the second region to form a modified layer; and removing the modified layer in the etching process step. In the etching process, the remaining silicon glass layer is used as a mask layer for the etching process to remove the doped layer and the dielectric layer covered by the modified layer.

6. The method for manufacturing a back contact battery according to claim 5, characterized in that, The dielectric layer includes a first dielectric layer, the doping element includes boron, the doping layer includes the first doping layer, and the silicon glass layer includes the borosilicate glass layer. The laser processing step includes: performing the laser processing on the borosilicate glass layer located in the second region to transform the borosilicate glass layer located in the second region into a first modified layer; The etching process includes: removing the first modified layer, and using the remaining borosilicate glass layer located on the first region as a mask layer to remove the first doped layer and the first dielectric layer covered by the first modified layer.

7. The method for manufacturing a back contact battery according to claim 5, characterized in that, The dielectric layer includes a second dielectric layer, the doping element includes phosphorus, the doping layer includes the second doping layer, and the silicon glass layer includes the phosphorosilicon glass layer; The laser processing step includes: performing the laser processing on the phosphosilicate glass layer located in the first region to transform the phosphosilicate glass layer located in the first region into a second modified layer; The etching process includes: removing the second modified layer, and using the remaining phosphosilicate glass layer located on the second region as a mask layer to remove the second doped layer and the second dielectric layer covered by the second modified layer.

8. A back-contact battery, characterized in that, This includes a back contact battery formed by the manufacturing method of a back contact battery as described in any one of claims 1 to 7.

9. A photovoltaic module, characterized in that, include: A battery string is formed by connecting multiple back contact batteries manufactured by any one of the methods of manufacturing back contact batteries as described in any one of claims 1 to 7, or by connecting back contact batteries as described in claim 8. An encapsulating film is used to cover the surface of the battery string; A cover plate is used to cover the surface of the encapsulating film that faces away from the battery string.

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