A back contact battery

Abstract

This invention provides a back-contact battery, comprising multiple back-contact battery cells. Each back-contact battery cell includes two spaced-apart structures of different conductivity types. A first conductivity type structure extends along the arrangement direction to form a fourth conductivity type structure, and a second conductivity type structure extends along the arrangement direction to form a fifth conductivity type structure. In the entire back-contact battery, a leakage region is formed between a portion of the second and fourth conductivity type structures. This leakage region provides a carrier recombination channel, reducing the risk of hot spots. Furthermore, this leakage region can be formed simultaneously during the fabrication process of the back-contact battery, simplifying the process and eliminating the need for additional processing steps.

Description

Technical Field

[0001] This utility model relates to the field of photovoltaic technology, and more specifically, to a back contact battery. Background Technology

[0002] A back-contact solar cell refers to a solar cell where the light-facing side of the cell has no electrodes, and both the positive and negative electrodes are located on the back-facing side of the cell. This reduces electrode shading of the cell, increases the short-circuit current, and improves the energy conversion efficiency of the cell. This type of back-contact solar cell includes multiple back-contact cell units. Each back-contact cell unit includes a first conductivity type structure and a second conductivity type structure, arranged along a first direction. A first electrode and a second electrode are respectively placed above the first conductivity type structure and the second conductivity type structure to form a fine grid. In the entire back-contact solar cell, the first conductivity type structure and the second conductivity type structure are extended along their arrangement direction to form a fourth conductivity type structure and a fifth conductivity type structure, respectively. A main grid electrode is placed above the fourth conductivity type structure and conductively connected to the first electrode above the first conductivity type structure. Similarly, a main grid electrode is placed above the fifth conductivity type structure and conductively connected to the second electrode above the second conductivity type structure.

[0003] To improve battery efficiency, the first, second, fourth, and fifth conductivity types are composed of contact passivation structures. These passivation structures typically consist of a passivation dielectric layer and doped polycrystalline silicon / doped amorphous silicon / microcrystalline silicon. In existing back-contact batteries, the first and fifth conductivity types, as well as the second and fourth conductivity types, are insulated from each other by insulating regions. This reduces reverse leakage current between the fine grid and the conductivity types below the main grid, thereby mitigating the risk of hot spots at the module end. (See attached manual) Figure 1 This diagram illustrates a prior art structure on a substrate 201 that is isolated from a second conductivity type structure by an insulating region. Figure 1 In the first structure, the second conductivity type includes a second dielectric layer 203 and a second doped layer 205, with a fine gate electrode 210 disposed on the second doped layer 205. The fourth conductivity type includes a fourth dielectric layer 202 and a fourth doped layer 204, with a main gate electrode 209 disposed above the fourth doped layer 204. The second conductivity type structure and the fourth conductivity type structure are insulated from each other by an insulating region 206.

[0004] Therefore, existing technologies require controlling the reverse leakage current of batteries to a low value during manufacturing. However, various defects exist during the fabrication process, leading to localized leakage points between the conductive structures below the fine grid and the main grid. This makes it very easy for back-contact batteries to exceed the controlled value of reverse leakage current, resulting in low battery manufacturing efficiency. Therefore, improving the structure and manufacturing process of back-contact batteries to reduce the risk of hot spots at the module end has become an important aspect affecting their reliability. Utility Model Content

[0005] This invention provides a back-contact solar cell. By providing a leakage channel between the conductive structures below the fine grid and the main grid, two doped layers with opposite conductivity types can achieve localized and uniform contact. This uniformly contacted leakage channel improves the cell's leakage capability, reduces the voltage across the cell when shaded, thereby reducing the heat generation power at the leakage point and lowering the risk of hot spots. Furthermore, by introducing a leakage channel at a predetermined location, this invention protects against hot spots caused by defects, reducing the requirements for defect control and improving the manufacturing capability of solar cells while lowering the risk of hot spots caused by defects. Moreover, this invention can form uniformly distributed pores as leakage channels in the dielectric layer through the diffusion formation step of the doped layer, based on existing back-contact solar cell fabrication processes. The process is simple and does not require additional processes to form the leakage channels.

[0006] The specific solution of the back contact battery of this utility model is as follows.

[0007] A back contact battery includes multiple back contact battery cells, each back contact battery cell including: a semiconductor substrate, a first conductivity type structure, and a second conductivity type structure; the first conductivity type structure includes a first dielectric layer and a first doped layer, and the second conductivity type structure includes a second dielectric layer and a second doped layer.

[0008] On a plane parallel to the semiconductor substrate, the first conductivity type structure and the second conductivity type structure are arranged at intervals along a first direction on one side of the backlight surface of the semiconductor substrate, and the first conductivity type structure and the second conductivity type structure extend along a second direction, with the first direction being perpendicular to the second direction.

[0009] The first dielectric layer and the second dielectric layer are formed on the back side of the semiconductor substrate. The first doped layer is located on the first dielectric layer and is doped with a first dopant. The second doped layer is located on the second dielectric layer and is doped with a second dopant. The first doped layer and the second doped layer have opposite conductivity types.

[0010] The first conductivity type structure extends along the first direction to form a fourth conductivity type structure, and the fourth conductivity type structure intersects the first conductivity type structure perpendicularly. The second conductivity type structure extends along the first direction to form a fifth conductivity type structure, and the fifth conductivity type structure intersects the second conductivity type structure perpendicularly. The fourth conductivity type structure includes a fourth dielectric layer and a fourth doped layer, and the fourth doped layer is doped with a first dopant. The fifth conductivity type structure includes a fifth dielectric layer and a fifth doped layer, and the fifth doped layer is doped with a second dopant.

[0011] In the entire back contact battery, a leakage region is included between a portion of the second conductivity type structure and the fourth conductivity type structure.

[0012] Furthermore, the leakage region includes a third dielectric layer and a third doped layer. The third doped layer has the same conductivity type as the second doped layer. The third doped layer is adjacent to the second doped layer through the third dielectric layer. The second dopant of the second doped layer diffuses through the third dielectric layer, forming a hole for carrier transport in a localized area of ​​the third dielectric layer, thus locally connecting the second doped layer and the fourth doped layer.

[0013] Furthermore, in the third dielectric layer, the pores are nanoscale.

[0014] Furthermore, the pores are uniformly distributed in the third dielectric layer.

[0015] Furthermore, the fourth dielectric layer and the second dielectric layer have a height difference along the thickness direction of the semiconductor substrate, and the height difference is less than or equal to 4 μm.

[0016] Furthermore, the fourth conductivity type structure also includes a first doped region, wherein the first dopant of the fourth doped layer penetrates the fourth dielectric layer to form a first doped region inside the semiconductor substrate;

[0017] The second conductivity type structure further includes a second doped region, wherein the second dopant of the second doped layer penetrates the second dielectric layer to form a second doped region inside the semiconductor substrate;

[0018] The leakage region also includes a third doped region and a fourth doped region, which are formed in the fourth doped layer and the first doped region respectively by the diffusion of the second dopant through the third dielectric layer.

[0019] Furthermore, the leakage region also includes: a first sub-doped layer and a first sub-dielectric layer.

[0020] The first sub-dielectric layer is located on the semiconductor substrate. Along the second direction, one side of the first sub-dielectric layer is connected to the third dielectric layer, and the other side is connected to the second dielectric layer.

[0021] The first sub-doped layer is located on the first sub-dielectric layer, and along the second direction, it is connected to the third doped layer on one side and to the second doped layer on the other side. The first sub-doped layer has the same conductivity type as the third doped layer and the second doped layer.

[0022] Furthermore, the first sub-doped layer, the third doped layer, and the second doped layer are integrally formed in the same process, and the first sub-dielectric layer, the third dielectric layer, and the second dielectric layer are integrally formed in the same process.

[0023] Furthermore, the leakage region includes: a second sub-doped layer and a second sub-dielectric layer.

[0024] The second sub-dielectric layer is located on the fourth doped layer, and in the second direction, one side of the second sub-dielectric layer is connected to the third dielectric layer.

[0025] The second sub-doped layer is located on the second sub-dielectric layer. In the second direction, one side of the second sub-doped layer is connected to the third doped layer. The second sub-doped layer and the third doped layer have the same conductivity type.

[0026] Furthermore, the second sub-doped layer, the third doped layer, and the second doped layer are integrally formed in the same process.

[0027] Furthermore, the thickness of the second sub-dielectric layer is 5nm-100nm.

[0028] Furthermore, a first electrode is provided on the first conductive type structure, and a fourth electrode is provided on the fourth conductive structure, the fourth electrode being perpendicularly intersecting the first electrode and conductively connected; a second electrode or a third electrode is provided on the second conductive type structure, and a fifth electrode is provided on the fifth conductive type structure, the fifth electrode being perpendicularly intersecting the second electrode or the third electrode and conductively connected.

[0029] Furthermore, a second electrode is provided on the second conductivity type structure without leakage region, and a third electrode is provided on the second conductivity type structure with leakage region. The distance between the end of the third electrode and the fourth doped layer is X7, and the distance between the end of the second electrode and the third doped layer is X6, where X7≤X6, 50μm≤X6≤800μm, and 50μm≤X7≤800μm.

[0030] Furthermore, the width of the portion of the fourth doped layer containing the leakage region is D4, and the thickness of the portion of the fourth doped layer without the leakage region is D3, where D3≤D4, 100μm≤D3≤2000μm, and 100μm≤D4≤2000μm.

[0031] Furthermore, along the second direction, the length of the second sub-doped layer on the fourth doped layer is X1, X1 < (1 / 2)D4, and along the first direction, the width of the second sub-doped layer on the fourth doped layer is X5, 5μm ≤ X5 ≤ 500μm.

[0032] Furthermore, for the second conductivity type structure with leakage regions, the spacing between the second doped layer and the third doped layer along the second direction is X4, and 5μm≤X4≤500μm.

[0033] Furthermore, along the first direction, the width of the first doped layer is D1, the width of the second doped layer is D2, 20μm≤D1≤500μm, and 20μm≤D2≤800μm.

[0034] Furthermore, along the first direction, the spacing between the second doped layer and the first doped layer is X2, and the spacing between the first doped layer and the second doped layer is X3, and 5μm≤X2≤500μm, and 5μm≤X3≤500μm.

[0035] Furthermore, when the back contact battery is a whole back contact battery, the number of leakage areas in the back contact battery is N1, 20≤N1≤2000; when the back contact battery is a 1 / N segment back contact battery, the number of leakage areas in the back contact battery is N2, 30 / N≤N2≤2000 / N, where N is a positive integer greater than or equal to 2. Attached Figure Description

[0036] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments of this utility model will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a top view of a back-contact battery in the prior art;

[0038] Figure 2 Cross-sectional view of the leakage connection area of ​​the back contact battery of this utility model. Figure 1 ;

[0039] Figure 3 Cross-sectional view of the leakage connection area of ​​the back contact battery of this utility model. Figure 2 ;

[0040] Figure 4 This is a top view of the back contact battery of this utility model;

[0041] Figure 5 This is a top enlarged view of the leakage area of ​​the back contact battery of this utility model;

[0042] Figure 6 This is an electron microscope image of the pores formed in the third dielectric layer of this invention.

[0043] In the figure, 101. Semiconductor substrate, 102. Fourth dielectric layer, 103. Second dielectric layer, 1031. First sub-dielectric layer, 1032. Second sub-dielectric layer, 1033. Third dielectric layer, 104. Fourth doped layer, 105. Second doped layer, 1051. First sub-doped layer, 1052. Second sub-doped layer, 1053. Third doped layer, 106. First doped region, 107. Second doped region, 109. Third doped region, 110. 1111. Fourth doped region, 113. Leakage region, 114. Leakage connection region, 111. First doped layer, 115. Fifth doped layer, 301. First electrode, 302. Second electrode, 306. Third electrode, 304. Fourth electrode, 305. Fifth electrode, 204. Fourth doped layer, 202. Fourth dielectric layer, 209. Main gate electrode, 205. Second doped layer, 203. Second dielectric layer, 210. Fine gate. Detailed Implementation

[0044] The technical solutions of the present invention will now be described with reference to the accompanying drawings in the embodiments of the present invention.

[0045] This embodiment provides a back-contact battery, as shown in the top view of the back-contact battery in this embodiment. Figure 4 and cross-sectional view of the leakage area Figure 2 As shown, it includes multiple back contact battery cells, each back contact battery cell including: a semiconductor substrate 101, a first conductivity type structure, and a second conductivity type structure; the first conductivity type structure includes a first dielectric layer (not shown in the figure) and a first doped layer 111, and the second conductivity type structure includes a second dielectric layer 103 and a second doped layer 105.

[0046] like Figure 4 As shown, on a plane parallel to the semiconductor substrate, a first conductivity type structure and a second conductivity type structure are arranged at intervals along a first direction on one side of the backlight surface of the semiconductor substrate, and the first conductivity type structure and the second conductivity type structure extend along a second direction, with the first direction being perpendicular to the second direction.

[0047] A first dielectric layer (not shown) and a second dielectric layer 103 are formed on the back side of a semiconductor substrate. A first doped layer 111 is located on the first dielectric layer and is doped with a first dopant. A second doped layer 105 is located on the second dielectric layer 103 and is doped with a second dopant. The first doped layer 111 and the second doped layer 105 have opposite conductivity types.

[0048] like Figure 4 As shown, a first conductivity type structure extends along a first direction to form a fourth conductivity type structure, which intersects the first conductivity type structure perpendicularly. A second conductivity type structure extends along the first direction to form a fifth conductivity type structure, which intersects the second conductivity type structure perpendicularly. Figure 2 As shown, the fourth conductivity type structure includes a fourth dielectric layer 102 and a fourth doped layer 104. The fourth conductivity type structure is an extension of the first conductivity type structure; therefore, both the fourth doped layer 104 and the first doped layer 111 are doped with a first dopant. The fifth conductivity type structure includes a fifth dielectric layer (not shown) and a fifth doped layer 115. Since the fifth conductivity type structure is an extension of the second conductivity type structure, the fifth doped layer 115 is identical to the second doped layer 105, both being doped with a second dopant.

[0049] Throughout the entire back contact battery, such as Figure 4 As shown, a first electrode 301 is provided on a first conductivity type structure, and a second electrode 302 or a third electrode 306 is provided on a second conductivity type structure. The first electrode 301, the second electrode 302, and the third electrode 306 form the fine grid of the back contact battery, and the conductivity type of the first electrode 301 is opposite to that of the second electrode 302 and the third electrode 306. A fourth electrode 304 is provided on a fourth conductivity type structure, and a fifth electrode 305 is provided on a fifth conductivity type structure. The fourth electrode 304 and the fifth electrode 305 form the main grid of the back contact battery, and their conductivity types are opposite. The first electrode 301 and the fourth electrode 304 have the same conductivity type and are conductively connected, and the second electrode 302, the third electrode 306, and the fifth electrode 305 have the same conductivity type and are conductively connected.

[0050] like Figure 4As shown, a leakage region 113 is provided between a portion of the second conductivity type structure and the fourth conductivity type structure. By providing the leakage region 113 between the fine grid and the main grid of the back contact battery, a leakage channel is formed, reducing the impact of the hot spot effect of the battery. Furthermore, by providing the leakage region 113 only between a portion of the second conductivity type structure and the fourth conductivity type structure, and by having no leakage region between the remaining portions of the second conductivity type structure and the fourth conductivity type structure, the number of leakage regions between the fine grid and the main grid in the entire back contact battery is reasonably controlled. This reduces the impact of the hot spot effect and avoids a decrease in the overall efficiency of the back contact battery due to an excessive number of leakage regions. Accordingly, a second electrode 302 is provided on the second conductivity type structure without a leakage region, and a third electrode 306 is provided on the second conductivity type structure with the leakage region 113.

[0051] The manufacturing process of the back contact battery provided in this embodiment includes the following steps.

[0052] Step 1: A fourth dielectric layer 102 and a fourth doped layer 104 are grown on the back side of the semiconductor substrate 101 to form a fourth conductivity type structure. At the same time, the first dopant of the fourth doped layer 104 diffuses downward through the fourth dielectric layer 102 to form a first doped region 106 in the semiconductor substrate.

[0053] Step 2: Grow a second sub-dielectric layer 1032 on top of the fourth conductivity type structure.

[0054] Step 3: Etch the fourth conductivity type structure and the second sub-dielectric layer 1032 formed on one side until the semiconductor substrate 101 is exposed, leaving the fourth conductivity type structure and the second sub-dielectric layer on the other side that have not been etched.

[0055] Step four: A first sub-dielectric layer 1031 and a second dielectric layer 103 are grown on the exposed side of the semiconductor substrate surface, and a third dielectric layer 1033 is grown along the thickness direction of the semiconductor substrate 101 on the side of the remaining first doped region 106, fourth dielectric layer 102, fourth doped layer 104, and second sub-dielectric layer 1032. The first sub-dielectric layer 1031, the second dielectric layer 103, and the third dielectric layer 1033 are integrally formed in this step; and there is a height difference between the first sub-dielectric layer 1031, the fourth dielectric layer 102, and the second dielectric layer 103, which is less than or equal to 4 μm.

[0056] Step 5: On the upper surface of the first sub-dielectric layer 1031 and the second sub-dielectric layer 103, the side surface of the third sub-dielectric layer 1033, and the upper surface of the second sub-dielectric layer 1032, respectively, the first sub-doped layer 1051, the second doped layer 105, the third doped layer 1053, and the second sub-doped layer 1052 are grown. The second doped layer 105, the first sub-doped layer 1051, the third doped layer 1053, and the second sub-doped layer 1052 have the same conductivity type, are all doped with the second dopant, and can be integrally formed in this step.

[0057] Simultaneously, the second dopant partially penetrates the first sub-dielectric layer 1031 and the second dielectric layer 103 along the thickness direction of the semiconductor substrate, forming carrier transport holes 110 locally in the first sub-dielectric layer 1031 and the second dielectric layer 103. The second dopant diffuses into the substrate 101 to form a second doped region 107. Furthermore, the second dopant also partially penetrates the third dielectric layer 1033 and diffuses into the fourth doped layer 104 and the first doped region 106, forming carrier transport holes 110 locally in the third dielectric layer 1033, forming a third doped region 109 in the fourth doped layer 104, and forming a fourth doped region 1111 in the first doped region 106. Therefore, the second doped region 107, the third doped region 109, and the fourth doped region 1111 have the same conductivity type and can be formed in the same step. Figure 6 The diagram shows two locations of textural discontinuity in the third dielectric layer 1033, namely the nanoscale pores 110 formed therein. The pores 110 formed in this invention are nanoscale in size and uniformly distributed, thus providing excellent carrier conduction while minimizing damage to the third dielectric layer 1033. Even after the pores 110 are formed, the third dielectric layer 1033 retains good passivation, preventing a reduction in the efficiency of the back contact battery.

[0058] Step six: On the plane of the parallel semiconductor substrate 101, a portion of the second sub-dielectric layer 1032 located above the fourth doped layer 104 and the second sub-doped layer 1052 located on the second sub-dielectric layer 1032 are removed to form a structure as shown in the figure. Figure 2 The structure shown.

[0059] This creates a leakage connection region 114 between the second conductive structure and the fourth conductive structure, such as... Figure 3 As shown in the figure, the structure 114 in the dashed box is the leakage connection area.

[0060] Step seven, as Figure 3 As shown, a portion of the leakage connection area 114 is removed along the first direction, reducing the width of the leakage connection area 114 along the first direction, forming as shown... Figure 4The leakage area 113 shown is designed to reduce the width of the leakage area 113 to avoid excessive leakage area in the back contact battery, which would reduce battery efficiency.

[0061] Therefore, as Figure 2-4 As shown, the leakage region 113 between the second conductivity type structure and the fourth conductivity type structure includes a third dielectric layer 1033 and a third doped layer 1053. The third doped layer 1053 has the same conductivity type as the second doped layer 105. The third doped layer 1053 is adjacent to the fourth doped layer 104 through the third dielectric layer 1033. The second dopant of the second doped layer 105 diffuses through the third dielectric layer 1033, forming a carrier transport hole 110 in a local area of ​​the third dielectric layer 1033, thus locally connecting the second doped layer 105 and the fourth doped layer 104.

[0062] like Figure 2 As shown, there is a height difference between the fourth dielectric layer 102 and the second dielectric layer 103 along the thickness direction of the semiconductor substrate 101, and the height difference is less than or equal to 4 μm.

[0063] The fourth conductivity type structure also includes a first doped region 106, where the first dopant of the fourth doped layer 104 penetrates the fourth dielectric layer 102 to form the first doped region 106 inside the semiconductor substrate 101; the second conductivity type structure also includes a second doped region 107, where the second dopant of the second doped layer 105 penetrates the second dielectric layer 103 to form the second doped region 107 inside the semiconductor substrate 101.

[0064] like Figure 2 As shown, the leakage region 113 also includes a third doped region 109 and a fourth doped region 1111. The third doped region 109 and the fourth doped region 1111 are formed in the fourth doped layer 104 and the first doped region 106 respectively by the diffusion of the second dopant through the third dielectric layer 1033.

[0065] Since the first doped region 106 and the second doped region 107 are formed by the first dopant and the second dopant penetrating the fourth dielectric layer 102 and the second dielectric layer 103, respectively, the doping concentration of the first doped region 106 and the second doped region 107 gradually decreases in the direction away from the back surface of the semiconductor substrate 101. The third doped region 109 and the fourth doped region 1111 are formed by the second dopant penetrating the third dielectric layer 1033 in the fourth doped layer 104 and the first doped region 106, respectively. Therefore, the highest doping concentration of the third doped region 109 is less than the doping concentration of the second doped layer 105, and the lowest doping concentration is equal to the doping concentration of the fourth doped layer 104. The highest doping concentration of the fourth doped region 1111 is less than the doping concentration of the second doped layer 105, and the lowest doping concentration is equal to the doping concentration of the first doped region 106 at the same depth as the fourth doped region 1111.

[0066] Specifically, the fourth doped layer 104 is a boron-doped polycrystalline silicon layer with a thickness of 300 nm and a doping concentration of 6.5E19 atm / cm. 3 .

[0067] The second doped layer 105 is a phosphorus-doped polycrystalline silicon layer with a thickness of 200 nm and a doping concentration of 7E20 atm / cm. 3 .

[0068] The depth of the first doped region 106 is 0.4 μm, and the highest doping concentration is 6.5E19 atm / cm. 3 .

[0069] The second doped region 107 has a depth of 0.35 μm and a maximum doping concentration of 7E20 atm / cm. 3 .

[0070] The third doped region 109 and the fourth doped region 1111 are phosphorus-doped polycrystalline silicon layers. Along the second direction, the depth of both the third doped region 109 and the fourth doped region 1111 is 0.06 μm, and the maximum doping concentration of both is 6.35E20 atm / cm. 3 .

[0071] In this example, the contact resistance between the formed third doped region 109, the fourth doped region 1111, and the third doped layer 1053 is 1.5 mol / cm². 2 The lower the contact resistance, the stronger the conduction of charge carriers between the fourth doped layer 104 and the second doped layer 105, and the higher the leakage current capability. Therefore, in addition to controlling the dopant concentration and diffusion temperature, the thickness of the third dielectric layer 1033 between the fourth doped layer 104 and the second doped layer 105 is controlled to reduce the contact resistance by increasing the density of the pores 110 within the dielectric layer and thus reducing the thickness of the dielectric layer.

[0072] Specifically, the thickness of the second dielectric layer 103, the first sub-dielectric layer 1031, and the third dielectric layer 1033 is 1.6 nm. In addition, the thickness of the fourth dielectric layer 102 is 1.9 nm.

[0073] In addition, the leakage region 113 also includes: a first sub-doped layer 1051 and a first sub-dielectric layer 1031. The first sub-dielectric layer 1031 is located on the semiconductor substrate 101. Along the second direction, one side of the first sub-dielectric layer 1031 is connected to the third dielectric layer 1033, and the other side is connected to the second dielectric layer 103. The first sub-doped layer 1051 is located on the first sub-dielectric layer 1031. Along the second direction, one side is connected to the third doped layer 1053, and the other side is connected to the second doped layer 105. The first sub-doped layer 1051 has the same conductivity type as the third doped layer 1053 and the second doped layer 105.

[0074] In addition, the leakage region 113 also includes a second sub-doped layer 1052 and a second sub-dielectric layer 1032. The second sub-dielectric layer 1032 is located on the fourth doped layer 104. In the second direction, one side of the second sub-dielectric layer 1032 is connected to the third dielectric layer 1033. The second sub-doped layer 1052 is located on the second sub-dielectric layer 1032. In the second direction, one side of the second sub-doped layer 1052 is connected to the third doped layer 1053. The second sub-doped layer 1052 and the third doped layer 1053 have the same conductivity type.

[0075] In the fabrication process, in order to protect the lower fourth doped layer 104, the thickness of the second sub-dielectric layer 1032 is relatively large, often set to the tens to hundreds of nanometers, which is much larger than the thickness of the fourth dielectric layer 102 and the second dielectric layer 103. In this embodiment, the thickness of the second sub-dielectric layer 1032 is 5nm-100nm.

[0076] like Figure 5 As shown, Figure 5 for Figure 4 The image includes an enlarged view of the leakage region 113. Along the second direction, the width of the portion of the fourth doped layer 104 containing the leakage region 113 is D4, and the thickness of the portion of the fourth doped layer 104 without the leakage region 113 is D3, where D3≤D4, 100μm≤D3≤2000μm, and 100μm≤D4≤2000μm.

[0077] Therefore, the distance between the end of the third electrode 306 on the second conductivity type structure with leakage region 113 and the fourth doped layer 104 is X7, and the distance between the end of the second electrode 302 on the second conductivity type structure without leakage region and the fourth doped layer is X6, where X7≤X6, 50μm≤X6≤800μm, and 50μm≤X7≤800μm. By extending the width of the portion of the fourth doped layer 104 opposite to the second conductivity type structure with leakage region along the second direction, the distance between the third electrode 306 and the fourth doped layer 104 on the second conductivity type structure with leakage region is reduced, thereby reducing the transport path of charge carriers from the fine gate to the main gate in the leakage channel, improving the recombination efficiency of charge carriers, and thus improving the efficiency of the leakage region and reducing the impact of hot spot effect.

[0078] like Figure 5 As shown, along the second direction, the length of the second sub-doped layer 1052 on the fourth doped layer 104 is X1, X1 < (1 / 2)D4, and along the first direction, the width of the second sub-doped layer 1052 on the fourth doped layer 104 is X5, 5μm≤X5≤500μm.

[0079] For the second conductivity type structure with leakage region, the spacing between the second doped layer 105 and the fourth doped layer 104 along the second direction is X4, and 5μm≤X4≤500μm.

[0080] like Figure 5 As shown, along the first direction, the width of the first doped layer 111 is D1, the width of the second doped layer 105 is D2, 20μm≤D1≤500μm, and 20μm≤D2≤800μm.

[0081] Along the first direction, the spacing between the second doped layer 105 and the first doped layer 111 is X2, and the spacing between the first doped layer 111 and the second doped layer 105 is X3, and 5μm≤X2≤500μm, 5μm≤X3≤500μm.

[0082] In this embodiment, when the back contact battery is a whole back contact battery, the number of leakage areas in the back contact battery is N1, 20≤N1≤2000; in this embodiment, when the back contact battery is a 1 / N segment back contact battery, the number of leakage areas in the back contact battery is N2, 30 / N≤N2≤2000 / N, where N is a positive integer greater than or equal to 2.

[0083] Table 1 shows the data from hot spot effect tests conducted on the comparative examples and the experimental examples of this invention. The comparative example is a back-contact battery with no leakage area between the second and fourth conductivity types. Experimental example 1 is a back-contact battery where leakage areas exist between some of the second and fourth conductivity types, and the number of leakage areas in experimental example 2 is greater than that in experimental example 1. Experimental examples 3 and 4 are back-contact batteries where leakage areas exist between some of the second and fourth conductivity types, and the number of leakage areas is the same. However, the X7 distance is 650 μm in experimental example 3 and 300 μm in experimental example 4. As shown in Table 1, compared to Comparative Example 1, Experimental Examples 1 and 2 have larger reverse currents and lower maximum reverse voltages compared to Comparative Example 1 because multiple leakage regions are set between the fourth type conductive structure and the second type conductive structure, and the number of leakage regions in Experimental Example 2 is greater than that in Experimental Example 1. The maximum hot spot temperature is also reduced to 140°C or even 130°C compared to 160°C in Comparative Example 1. In Experimental Examples 3 and 4, the same number of leakage regions are set between the fourth type conductive structure and the first type conductive structure. However, in Experimental Example 4, the distance X7 between the end of the third electrode 306 on the second conductive type structure with leakage region 113 and the fourth doped layer 104 is smaller. Therefore, the carrier transport speed from the second doped layer to the fourth doped layer is faster, improving the leakage effect. Experimental Example 4 has a lower maximum hot spot temperature than Experimental Example 3, which can be reduced to 100°C.

[0084] Table 1. Test results of Experimental Examples 1-4 and Comparative Example 1

[0085] Comparative Example 1 0.2A 17V 160℃ / Experimental Example 1 5A 15V 140℃ -0.05％ Experimental Example 2 10A 12V 130℃ -0.08％ Experimental Example 3 15A 8V 120℃ -0.1％ Test Example 4 20A 5V 100℃ -0.12％

[0086] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A back contact cell comprising a plurality of back contact cell units, each back contact cell unit comprising: Semiconductor substrate, first conductivity type structure, second conductivity type structure; The first conductivity type structure includes a first dielectric layer and a first doped layer, and the second conductivity type structure includes a second dielectric layer and a second doped layer; On a plane parallel to the semiconductor substrate, the first conductivity type structure and the second conductivity type structure are arranged at intervals along a first direction on one side of the backlight surface of the semiconductor substrate, and the first conductivity type structure and the second conductivity type structure extend along a second direction, with the first direction being perpendicular to the second direction. The first dielectric layer and the second dielectric layer are formed on the back side of the semiconductor substrate. The first doped layer is located on the first dielectric layer and is doped with a first dopant. The second doped layer is located on the second dielectric layer and is doped with a second dopant. The first doped layer and the second doped layer have opposite conductivity types. The first conductivity type structure extends along the first direction to form a fourth conductivity type structure, which intersects the first conductivity type structure perpendicularly; the second conductivity type structure extends along the first direction to form a fifth conductivity type structure, which intersects the second conductivity type structure perpendicularly; the fourth conductivity type structure includes a fourth dielectric layer and a fourth doped layer, wherein the fourth doped layer is doped with a first dopant; the fifth conductivity type structure includes a fifth dielectric layer and a fifth doped layer, wherein the fifth doped layer is doped with a second dopant. In the entire back contact battery, a leakage region is included between a portion of the second conductivity type structure and the fourth conductivity type structure.

2. A back contact cell according to claim 1, wherein, The leakage region includes a third dielectric layer and a third doped layer. The third doped layer has the same conductivity type as the second doped layer. The third doped layer is adjacent to the second doped layer through the third dielectric layer. The second dopant of the second doped layer diffuses through the third dielectric layer, forming a hole for carrier transport in a localized part of the third dielectric layer, thus locally connecting the second doped layer and the fourth doped layer.

3. A back contact cell according to claim 2, wherein, In the third dielectric layer, the pores are nanoscale.

4. A back contact cell according to claim 2, wherein, In the third dielectric layer, the pores are evenly distributed.

5. A back contact cell according to claim 2, wherein, The fourth dielectric layer and the second dielectric layer have a height difference along the thickness direction of the semiconductor substrate, and the height difference is less than or equal to 4 μm.

6. A back contact battery according to claim 5, characterized in that, The fourth conductivity type structure further includes a first doped region, wherein the first dopant of the fourth doped layer penetrates the fourth dielectric layer to form a first doped region inside the semiconductor substrate; The second conductivity type structure further includes a second doped region, wherein the second dopant of the second doped layer penetrates the second dielectric layer to form a second doped region inside the semiconductor substrate; The leakage region also includes a third doped region and a fourth doped region, which are formed in the fourth doped layer and the first doped region respectively by the diffusion of the second dopant through the third dielectric layer.

7. A back contact cell according to claim 2, wherein, The leakage region further includes: a first sub-doped layer and a first sub-dielectric layer. The first sub-dielectric layer is located on the semiconductor substrate. Along the second direction, one side of the first sub-dielectric layer is connected to the third dielectric layer, and the other side is connected to the second dielectric layer. The first sub-doped layer is located on the first sub-dielectric layer, and along the second direction, it is connected to the third doped layer on one side and to the second doped layer on the other side. The first sub-doped layer has the same conductivity type as the third doped layer and the second doped layer.

8. A back contact cell according to claim 7, wherein, The first sub-doped layer, the third doped layer, and the second doped layer are integrally formed in the same process, and the first sub-dielectric layer, the third dielectric layer, and the second dielectric layer are integrally formed in the same process.

9. A back contact cell according to claim 2, wherein, The leakage region includes: a second sub-doped layer and a second sub-dielectric layer. The second sub-dielectric layer is located on the fourth doped layer, and in the second direction, one side of the second sub-dielectric layer is connected to the third dielectric layer. The second sub-doped layer is located on the second sub-dielectric layer. In the second direction, one side of the second sub-doped layer is connected to the third doped layer. The second sub-doped layer and the third doped layer have the same conductivity type.

10. A back contact cell according to claim 9, wherein, The second sub-doped layer, the third doped layer, and the second doped layer are integrally formed in the same process.

11. A back contact cell according to claim 9, wherein, The thickness of the second sub-dielectric layer is 5nm-100nm.

12. A back contact cell according to claim 2, wherein, A first electrode is provided on the first conductive structure, and a fourth electrode is provided on the fourth conductive structure. The fourth electrode intersects the first electrode perpendicularly and is conductively connected to it. A second electrode or a third electrode is provided on the second conductivity type structure, and a fifth electrode is provided on the fifth conductivity type structure. The fifth electrode intersects the second electrode or the third electrode perpendicularly and is electrically connected to it.

13. A back contact cell according to claim 12, wherein, A second electrode is provided on the second conductivity type structure without leakage region, and a third electrode is provided on the second conductivity type structure with leakage region. The distance between the end of the third electrode and the fourth doped layer is X7, and the distance between the end of the second electrode and the third doped layer is X6. X7≤X6, 50μm≤X6≤800μm, 50μm≤X7≤800μm.

14. The back contact cell of claim 9, wherein, Along the second direction, the width of the portion of the fourth doped layer containing the leakage region is D4, and the thickness of the portion of the fourth doped layer without the leakage region is D3, where D3≤D4, 100μm≤D3≤2000μm, and 100μm≤D4≤2000μm.

15. A back contact cell according to claim 14, wherein, Along the second direction, the length of the second sub-doped layer on the fourth doped layer is X1, X1 < (1 / 2)D4, and along the first direction, the width of the second sub-doped layer on the fourth doped layer is X5, 5μm ≤ X5 ≤ 500μm.

16. The back contact cell of claim 13, wherein, For the second conductivity type structure with leakage regions, the spacing between the second doped layer and the third doped layer along the second direction is X4, and 5μm≤X4≤500μm.

17. A back contact cell according to claim 2, wherein, Along the first direction, the width of the first doped layer is D1, the width of the second doped layer is D2, 20μm≤D1≤500μm, and 20μm≤D2≤800μm.

18. A back contact cell according to claim 2, wherein, Along the first direction, the spacing between the second doped layer and the first doped layer is X2, and the spacing between the first doped layer and the second doped layer is X3, and 5μm≤X2≤500μm, and 5μm≤X3≤500μm.

19. A back contact battery according to claim 6, characterized in that, When the back contact battery is a whole back contact battery, the number of leakage areas in the back contact battery is N1, 20≤N1≤2000; when the back contact battery is a 1 / N segment back contact battery, the number of leakage areas in the back contact battery is N2, 30 / N≤N2≤2000 / N, where N is a positive integer greater than or equal to 2.

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