A passivation contact structure and solar cell

Abstract

The present application discloses a passivation contact structure and a solar cell, wherein the passivation contact structure comprises a substrate, wherein the first doping layer is arranged on a first surface area of ​​the substrate, wherein the passivation tunneling layer is arranged on at least a partial area of ​​the surface of the first doping layer away from the substrate, wherein the doping film layer is arranged on a partial area of ​​the surface of the passivation tunneling layer away from the first doping layer, wherein the first dielectric film layer is arranged on an area formed by the surfaces of the first doping layer, the doping film layer and the passivation tunneling layer; wherein the first electrode contacts the doping film layer through the first dielectric film layer. Separating the first doping layer from the first electrode can effectively shield the high recombination effect of the first electrode, significantly reduce surface recombination, provide good surface passivation for the cell, and thus improve the conversion efficiency of the solar cell.

Description

Technical Field

[0001] The present invention generally relates to the technical field of solar cells, and in particular to a passivation contact structure and a solar cell. Background Art

[0002] The current solar cell structure is to prepare a doping layer on the surface of the solar cell, and then prepare a dielectric film layer and a metal electrode on it. In this case, the metal electrode and the doping layer are in direct contact. Usually, due to the contact between the metal and the semiconductor, a carrier recombination center is formed, resulting in an extremely high recombination rate of the solar cell carriers, which affects the passivation performance and thus causes a significant decrease in the battery performance. Therefore, there is a need for a better way to reduce the impact of metal recombination on passivation. Summary of the invention

[0003] In view of the above defects or deficiencies in the prior art, it is desirable to provide a passivation contact structure and a solar cell.

[0004] In order to overcome the deficiencies of the prior art, the technical solution provided by the present invention is:

[0005] A passivation contact structure, which is special in that it includes a substrate, a first doping layer, a passivation tunneling layer, a doping film layer, a first dielectric film layer and a first electrode;

[0006] The first doping layer is disposed on the first surface area of ​​the substrate;

[0007] The passivation tunneling layer is disposed on at least a partial area of ​​the surface of the first doped layer away from the substrate;

[0008] The doped film layer is disposed on a local area of ​​the surface of the passivation tunneling layer away from the first doped layer;

[0009] The first dielectric film layer is disposed on the area formed by the first doped layer, the doped film layer and the surface of the passivation tunneling layer;

[0010] The first electrode passes through the first dielectric film layer and contacts the doped film layer.

[0011] Furthermore, the passivation tunneling layer and the first doping layer have the same area, and the first dielectric film layer is disposed on a region formed jointly by the surfaces of the passivation tunneling layer and the doping film layer.

[0012] Furthermore, the passivation tunneling layer and the doped film layer have the same area size, and the first dielectric film layer is arranged on a region formed by the surfaces of the first doped layer, the passivation tunneling layer and the doped film layer.

[0013] Furthermore, the doped film layer includes a semiconductor material and a doping element, the semiconductor material includes one or more of polycrystalline silicon and amorphous silicon; the doping element includes one of the fifth main group elements or the third main group elements.

[0014] Furthermore, the concentration of the doping element is greater than 1×10 15 Pieces / cm 3 .

[0015] Furthermore, the thickness of the doped film layer is 5-300 nm.

[0016] Furthermore, the passivation tunneling layer includes one of silicon oxide, silicon oxynitride, amorphous silicon, aluminum oxide, titanium oxide, silicon nitride and silicon carbide.

[0017] Furthermore, the thickness of the passivation tunneling layer is 0.1-5 nm.

[0018] Furthermore, the square resistance of the first doped layer is 50 ohm / sq-300 ohm / sq.

[0019] In a second aspect, the present invention further provides a solar cell, which is special in that it includes a second dielectric film layer, a second electrode and the passivation contact structure, the second dielectric film layer is arranged on the second surface area of ​​the substrate, and the second electrode contacts the substrate through the second dielectric film layer.

[0020] Furthermore, the substrate in the passivation contact structure is a p-type silicon substrate, the first doped layer is an n-type doped layer, and the doped film layer is an n-type doped film layer.

[0021] Furthermore, the doped film layer includes a semiconductor material and a doping element, the semiconductor material includes one or more of polycrystalline silicon and amorphous silicon; and the doping element includes one of the fifth main group elements.

[0022] Furthermore, the first dielectric film layer and the second dielectric film layer both include one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, and silicon carbide.

[0023] In a third aspect, the present invention also provides a solar cell, which is special in that it includes a second doping layer, a second dielectric film layer, a second electrode and the passivation contact structure, the second doping layer is arranged on the second surface area of ​​the substrate, the second dielectric film layer is arranged on the second doping layer, and the second electrode passes through the second dielectric film layer to contact the second doping layer.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The passivation contact structure of the present invention comprises a substrate, the first doping layer is arranged on the first surface area of ​​the substrate, the passivation tunneling layer is arranged on at least a local area of ​​the surface of the first doping layer away from the substrate, the doping film layer is arranged on a local area of ​​the surface of the passivation tunneling layer away from the first doping layer, and the first dielectric film layer is arranged on the area formed by the first doping layer, the doping film layer and the surface of the passivation tunneling layer; the first electrode contacts the doping film layer through the first dielectric film layer. Separating the first doping layer from the first electrode can effectively shield the high recombination effect of the first electrode, significantly reduce surface recombination, provide good surface passivation for the battery, and thus improve the conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0027] Figure 1 A first structural diagram of a passivation contact structure provided by an embodiment of the present invention;

[0028] Figure 2 A second structural diagram of a passivation contact structure provided by an embodiment of the present invention;

[0029] Figure 3 A third structural diagram of a passivation contact structure provided by an embodiment of the present invention;

[0030] Figure 4 A first structural diagram of a p-type silicon substrate single-sided solar cell provided in an embodiment of the present invention;

[0031] Figure 5 for Figure 4 A schematic diagram of the distribution of the first electrode;

[0032] Figure 6 for Figure 4 Schematic diagram of the distribution of the second electrode;

[0033] Figure 7 A structural diagram of a p-type silicon substrate bifacial solar cell provided in an embodiment of the present invention;

[0034] Figure 8 for Figure 7 A schematic diagram of the distribution of the first electrode;

[0035] Fig. 9 for Figure 7 Schematic diagram of the distribution of the second electrode;

[0036] Fig.10 A structural diagram of a p-type silicon substrate bifacial solar cell including a second contact electrode doping layer provided in an embodiment of the present invention;

[0037] Fig.11 A structural diagram of an n-type silicon substrate bifacial solar cell provided by an embodiment of the present invention;

[0038] Fig.12 A second structural diagram of a p-type silicon substrate bifacial solar cell provided in an embodiment of the present invention.

[0039] In the figure: 1-substrate, 2-first doped layer, 3-passivation tunneling layer, 4-doped film layer, 5-first dielectric film layer, 6-second dielectric film layer, 7-first contact electrode, 8-first connecting electrode, 9-second contact electrode, 10-second connecting electrode, 11-second contact electrode doped layer, 12-alloy layer. DETAILED DESCRIPTION

[0040] The present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It is also necessary to explain that, for ease of description, only the parts related to the invention are shown in the accompanying drawings.

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] As mentioned in the background technology, the current solar cell structure is to prepare a doping layer on the surface of the solar cell, and then prepare a dielectric film layer and a metal electrode thereon. In this case, the metal electrode and the doping layer are in direct contact with each other. Usually, due to the contact between the metal and the semiconductor, a carrier recombination center is formed, resulting in an extremely high recombination rate of the solar cell carriers, which affects the passivation performance and thus causes a significant decrease in the battery performance. Therefore, there is a need for a better way to reduce the impact of metal recombination on passivation.

[0043] See also Figure 1 The present embodiment provides a passivation contact structure, including a substrate 1, a first doping layer 2 of a doping layer, a passivation tunneling layer, a doping film layer, a first dielectric film layer 5 and a first electrode; the first doping layer 2 of the doping layer is compositely arranged on a first surface area of ​​the substrate 1; the passivation tunneling layer 3 is compositely arranged on at least a local area of ​​the surface of the first doping layer 2 of the doping layer away from the substrate 1; the doping film layer 4 is compositely arranged on a local area of ​​the surface of the passivation tunneling layer 3 away from the first doping layer 2 of the doping layer; the first dielectric film layer 5 is compositely arranged on an area jointly formed by the surfaces of the first doping layer 2 of the doping layer, the doping film layer 4 and the passivation tunneling layer 3; the first electrode contacts the doping film layer 4 through the first dielectric film layer 5.

[0044] The first electrode is a metal electrode. After passing through the first dielectric film layer 5, the first electrode only forms contact with the doped film layer 4. Since the first electrode does not contact the emitter of the first doped layer 2, the high recombination effect of the metal contact is shielded, which can greatly reduce the recombination rate of the above-mentioned solar cell passivation contact area, thereby improving the cell conversion efficiency.

[0045] See also Figure 2 As an implementable manner, the passivation tunneling layer 3 has the same area as the first doping layer 2 , and the first dielectric film layer 5 is disposed on a region formed jointly by the surfaces of the passivation tunneling layer 3 and the doping film layer 4 .

[0046] See also Figure 3 As a feasible method, the passivation tunneling layer 3 has the same area as the doped film layer 4, and the first dielectric film layer 5 is arranged on the area jointly formed by the surfaces of the first doped layer 2, the passivation tunneling layer 3 and the doped film layer 4.

[0047] The present application has no particular restrictions on the substrate 1, the first doping layer 2 and the doping film layer 4. The substrate 1 of the solar cell known to those skilled in the art can be used, and those skilled in the art can select and adjust according to the actual application and product performance. The principle that can be followed is: using a substrate 1 with a first conductivity type, using a first doping layer 2 and a doping film layer 4 with a second conductivity type. Of course, the principle that can also be followed is: using a substrate 1 with a first conductivity type, using a first doping layer 2 and a doping film layer 4 with the same first conductivity type.

[0048] Specifically, the material of the substrate 1 of the present application can be a p-type silicon substrate or an n-type silicon substrate. When the material of the substrate 1 is a p-type silicon substrate, the first doped layer 2 is an n-type doped layer, and the doped film layer 4 is an n-type doped film layer; when the material of the substrate 1 is an n-type silicon substrate, the first doped layer 2 is a p-type doped layer, and the doped film layer 4 is a p-type doped film layer.

[0049] Similarly, the material of the substrate 1 of the present application can be a p-type silicon substrate or an n-type silicon substrate. When the material of the substrate 1 is a p-type silicon substrate, the first doping layer 2 is a p-type doping layer, and the doping film layer 4 is a p-type doping film layer; when the material of the substrate 1 is an n-type silicon substrate, the first doping layer 2 is an n-type doping layer, and the doping film layer 4 is an n-type doping film layer.

[0050] The doped film layer 4 of the present application includes a semiconductor material and a doping element. The semiconductor material includes one or more of polycrystalline silicon and amorphous silicon; and the doping element includes one of the fifth main group elements.

[0051] The present application has no particular restrictions on the specific composition of the semiconductor material. Those skilled in the art can make selections and adjustments based on actual application conditions and product performance. One composition form is to use polycrystalline silicon as the semiconductor material; another composition form is to use a mixture of amorphous silicon and polycrystalline silicon to form the semiconductor material.

[0052] When amorphous silicon and polycrystalline silicon are used as semiconductor materials, there is no particular restriction on the mixing ratio of the two. Those skilled in the art can select and adjust according to actual application conditions and product performance. For example, in a specific solution, polycrystalline silicon accounts for 70% and amorphous silicon accounts for 30%.

[0053] The concentration of the doping element is greater than 1×10 15 Pieces / cm 3 , the optimized doping concentration is greater than 1×10 17 Pieces / cm 3 , the more optimized doping concentration is greater than 1×10 19 Pieces / cm 3 If a higher concentration such as 1×10 20 Pieces / cm 3 The higher the doping concentration of the doped film layer 4 is, the lower its resistivity is, which can provide better current transmission performance and electrode contact performance.

[0054] The present application does not specifically limit which element of the fifth main group element the doping element is. Those skilled in the art can select and adjust according to the actual application and product performance. Boron or phosphorus can be used as the doping element. When boron is used as the doping element, the doping concentration of boron is 1×10 17 Pieces / cm 3 When phosphorus is used as the doping element, the doping concentration of phosphorus is 2×10 20 Pieces / cm 3 .

[0055] The thickness of the doping film layer 4 is 5-300 nm, preferably 10-250 nm, more preferably 50-150 nm, and most preferably 100 nm. Those skilled in the art can select and adjust according to actual application conditions and product performance.

[0056] The passivation tunneling layer includes one of silicon oxide, silicon oxynitride, amorphous silicon, aluminum oxide, titanium oxide, silicon nitride and silicon carbide, and a preferred solution includes one of silicon oxide, titanium oxide and silicon carbide.

[0057] The thickness of the passivation tunneling layer is 0.1-5 nm, preferably 1-5 nm, and more preferably 2 nm. The passivation tunneling layer should not be too thick. If the passivation tunneling layer is too thick, the probability of carriers passing through will be greatly reduced, thereby making the electrical transmission effect worse.

[0058] The sheet resistance of the first doped layer 2 should not be too high, generally 50ohm / sq-300ohm / sq, and the preferred solution is that the sheet resistance of the first doped layer 2 can be 100ohm / sq, 150ohm / sq, 200ohm / sq, etc. Although a higher sheet resistance may slightly increase the lateral transmission resistance, it can provide a lower surface recombination rate and improve the open circuit voltage and short circuit current of the battery. Therefore, under this sheet resistance condition, the implementation method can be optimized to achieve a higher battery conversion efficiency.

[0059] The embodiment of the present invention further provides a single-sided solar cell. When the material of the substrate 1 is a p-type silicon substrate, the first doping layer 2 is an n-type doping layer, and the doping film layer 4 is an n-type doping film layer. Figures 4 to 10 As shown. The doping element is selected from one of the fifth main group elements. The solar cell comprises a second dielectric film layer 6, a second electrode and the above-mentioned passivation contact structure, the second dielectric film layer 6 is arranged on the second surface area of ​​the substrate 1, and the second electrode contacts the substrate 1 through the second dielectric film layer 6.

[0060] When the material of the substrate 1 is an n-type silicon substrate, the first doping layer 2 is a p-type doping layer, and the doping film layer 4 is a p-type doping film layer. Fig.11 As shown, the solar cell includes a second doping layer, a second dielectric film layer, a second electrode and according to the aforementioned passivation contact structure, the second doping layer is arranged on the second surface area of ​​the substrate, the second dielectric film layer is arranged on the second doping layer, and the second electrode contacts the second doping layer through the second dielectric film layer.

[0061] It should be noted that the first surface refers to one surface of the solar cell, and the second surface refers to the other surface of the solar cell, and does not specifically refer to the front or back of the solar cell. When the first surface refers to the front of the solar cell, the structure of the solar cell is as follows: Figures 4 to 11 As shown, the doping element of the doped film layer is selected from one of the fifth main group elements; when the first surface refers to the back side of the solar cell, the structure of the solar cell is as shown in Fig.12 shown.

[0062] The first dielectric film layer 5 and the second dielectric film layer 6 both include one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, and silicon carbide. Preferably, one or more of silicon nitride, silicon oxide, and titanium oxide are used. More preferably, silicon nitride and silicon oxide stacks are used. Those skilled in the art can make selections and adjustments based on actual application conditions and product performance.

[0063] The thickness of the first dielectric film layer 5 and the second dielectric film layer 6 is 40-100 nm, preferably 60-90 nm, and more preferably 85 nm.

[0064] The overall refractive index of the first dielectric film layer 5 and the second dielectric film layer 6 is 2.00-2.20, preferably 2.05-2.15, and more preferably 2.10.

[0065] Figures 4 to 6 A schematic structural diagram of a single-sided solar cell provided in an embodiment of the present invention.

[0066] The first electrode includes a first contact electrode 7 and a first connection electrode 8. Both the first connection electrode 8 and the first contact electrode 7 are in the shape of long strips, extending from one side of the battery to the other side opposite thereto. The first connection electrode 8 and the first contact electrode 7 are arranged in directions perpendicular to each other and connected at the intersection, and current is derived through the first connection electrode 8.

[0067] The first contact electrode 7 passes through the first dielectric film layer 5 and contacts the doped film layer 4. The first connecting electrode 8 has two settings, one of which is to pass through the first dielectric film layer 5 and contact the doped film layer 4, and the other is not to contact the doped film layer 4 and is directly set on the first dielectric film layer 5.

[0068] The present application has no particular limitation on the number of the first contact electrodes 7 and the first connecting electrodes 8 , and those skilled in the art may select and adjust the number according to actual application conditions and product performance. Preferably, the number of the first contact electrodes 7 is 100 and the number of the first connecting electrodes 8 is 4.

[0069] The present application has no particular restrictions on the materials of the first contact electrode 7 and the first connection electrode 8. Those skilled in the art can select and adjust according to the actual application and product performance. The materials of the first contact electrode 7 and / or the first connection electrode 8 include but are not limited to one or more of silver, copper, and nickel. The preferred solution is silver. For example, the first contact electrode 7 uses silver paste that penetrates the first dielectric film layer 5 as the paste, and the first connection electrode 8 uses conductive paste that does not penetrate the first dielectric film layer 5.

[0070] The second electrode includes a second contact electrode 9 and a second connection electrode 10. The second connection electrode 10 is in the shape of a short strip, and a plurality of second connection electrodes 10 in the shape of a short strip are arranged in an array. The second contact electrode 9 is coated on the second dielectric film layer 6, except for the area where the second connection electrode 10 is set, so that the second contact electrode 9 is in direct contact with the substrate 1 to extract the current.

[0071] Figures 7 to 9 A schematic diagram of the structure of a double-sided solar cell provided in an embodiment of the present invention.

[0072] The first electrode of the bifacial solar cell includes a first contact electrode 7 and a first connecting electrode 8, which are arranged in the same manner as the above-mentioned single-sided solar cell.

[0073] The second electrode includes a second contact electrode 9 and a second connection electrode 10. The second connection electrode 10 and the second connection electrode 10 are both in the shape of a long strip, extending from one side of the battery to the other side opposite thereto. The second connection electrode 10 and the second contact electrode 9 are arranged in directions perpendicular to each other and connected at the intersection, and current is derived through the second connection electrode 10.

[0074] Fig.10 Another schematic diagram of the structure of a double-sided solar cell provided in an embodiment of the present invention.

[0075] Similar to the above structure, the difference is that a second contact electrode doping layer 11 of group III elements is included between the second contact electrode 9 and the substrate 1. Since the doping concentration of the second contact electrode doping layer 11 is higher than that of the substrate 1, there is a back surface field effect, which can increase the open circuit voltage of the battery.

[0076] As a further optimization scheme, an alloy layer 12 may also exist between the doping layer of the second contact electrode 9 and the second contact electrode 9, and the alloy layer 12 may greatly improve the current collection function of the substrate 1 and the second electrode, thereby improving the performance of the battery. This application does not particularly limit the above alloy material, and those skilled in the art may select and adjust it according to the actual application and product performance. The preferred scheme is to use aluminum silicon alloy.

[0077] The present application has no particular restrictions on the materials of the second contact electrode 9 and the second connecting electrode 10. Those skilled in the art may select and adjust the materials according to the actual application and product performance. The materials of the second contact electrode 9 and / or the second connecting electrode 10 include but are not limited to one or more of silver, copper, aluminum and nickel. A preferred solution is that the second contact electrode 9 uses an aluminum-containing material, and the second connecting electrode 10 uses a silver paste that does not penetrate the second dielectric film layer 6 as the paste.

[0078] Aluminum paste is first printed on the back using the screen printing method, and the laser opening position is covered with long strips of aluminum paste. The width of the aluminum paste line is 150mm, and the aluminum paste line completely covers the laser opening position; then the screen printing method is used to form silver connection electrodes with the same shape and number as the front connection electrodes on the back.

[0079] This embodiment provides a method for preparing a solar cell. The following uses p-type monocrystalline silicon as the substrate 1 of the solar cell to describe in detail the method for preparing a single-sided solar cell and a double-sided solar cell.

[0080] The preparation method of the single-sided solar cell is as follows:

[0081] 1) The substrate 1 is subjected to damage removal, surface texturing and cleaning.

[0082] The substrate 1 is dedamaged using a 50-70°C solution containing KOH, and surface textured using a solution containing KOH at 60-100°C to form a 2-5um pyramid velvet surface, and cleaned using a mixed solution containing hydrofluoric acid and hydrochloric acid, and then dried after cleaning.

[0083] 2) Doping is performed on the first pyramid velvet surface of the substrate 1.

[0084] A tubular diffusion furnace is used to diffuse POCl3 to form a pn junction in one go. The temperature of the entire process condition is 750-840°C and the time is 60-120 minutes. After the pn junction is formed, a solution containing HNO3 and HF acid is used to dope phosphosilicate glass and multiple edges, and the excess doping on the back is removed. It is then cleaned in turn with NaOH, water, hydrofluoric acid, and deionized water, and dried after cleaning.

[0085] 3) A passivation tunneling layer 3 and a doping film layer 4 are prepared on the front side of the substrate 1 .

[0086] A silicon oxide tunneling layer is prepared using a low pressure chemical vapor deposition device, and a layer of n-type polysilicon doped film layer 4 doped with phosphorus is further prepared on the silicon oxide tunneling layer.

[0087] 4) Localization of the doped film layer 4.

[0088] A mask is prepared on the surface of the doped film layer 4 using a screen printing mask, and the mask does not react with the alkaline solution; then the doped film layer 4 is corroded using a tetramethylammonium hydroxide solution; the doped film layer 4 outside the first electrode region is removed, and the passivation tunneling layer 3 is exposed; then it is cleaned using a hydrochloric acid solution and deionized water.

[0089] 5) Preparation of the first dielectric film layer 5 and the second dielectric film layer 6.

[0090] Enhanced plasma chemical vapor deposition is used to deposit a silicon nitride stack on the front of the battery to complete the preparation of the first dielectric film layer 5; enhanced plasma chemical vapor deposition is used to deposit a 5-10nm aluminum oxide layer on the back of the battery, and 80-120nm silicon nitride is deposited thereon to complete the preparation of the second dielectric film layer.

[0091] 6) Preparation of the first electrode and the second electrode.

[0092] A laser is used to make a hole in the first dielectric film layer 5, and the scanning method is to perform pulsed local laser irradiation treatment on the second dielectric film layer 6. The scanning direction is along the parallel line direction of the doping. The second dielectric film layer 6 forms a hole in the area irradiated by the laser spot, and no contact hole is formed in the unirradiated area. After the laser hole is opened in this contact hole area, the second dielectric film layer 6 is removed. The wavelength of the hole opening laser is 532nm, the spot size is 80um diameter circle, the scanning speed is 10000mm / s, and the frequency is 10kHz.

[0093] Conductive material is coated on the areas on the first and second sides of the battery after laser scanning. In this embodiment, we use screen printing to graphically apply the conductive paste. Silver paste is used as the paste for the first contact electrode 7 to fill the multiple parallel long strip first contact electrode 7 setting areas formed by scanning; a conductive paste that does not penetrate the first dielectric film layer 5 is used to fill the setting area of ​​the first connection electrode 8 that is perpendicular to the first contact electrode 7. The second contact electrode 9 uses aluminum paste as the paste to fill the multiple short strip second connection electrode 10 setting areas arranged in an array formed by scanning. The second connection electrode 10 uses silver paste that does not penetrate the second dielectric film layer 6 as the paste to fill the remaining areas except the setting area of ​​the second connection electrode 10 formed by scanning.

[0094] The preparation method of the bifacial solar cell is as follows:

[0095] 1) The substrate 1 is subjected to damage removal, surface texturing and cleaning.

[0096] The substrate 1 is dedamaged using a 50-70°C solution containing KOH, and surface textured using a solution containing KOH at 60-100°C to form a 2-5um pyramid velvet surface, and cleaned using a mixed solution containing hydrofluoric acid and hydrochloric acid, and then dried after cleaning.

[0097] 2) Doping is performed on the first pyramid velvet surface of the substrate 1.

[0098] A tubular diffusion furnace is used to diffuse POCl3 to form a pn junction in one go. The temperature of the entire process condition is 750-840°C and the time is 60-120 minutes. After the pn junction is formed, a solution containing HNO3 and HF acid is used to dope phosphosilicate glass and multiple edges, and the excess doping on the back is removed. It is then cleaned in turn with NaOH, water, hydrofluoric acid, and deionized water, and dried after cleaning.

[0099] 3) A passivation tunneling layer 3 and a doping film layer 4 are prepared on the front side of the substrate 1 .

[0100] A silicon oxide tunneling layer is prepared using a low pressure chemical vapor deposition device, and a layer of n-type polysilicon doped film layer 4 doped with phosphorus is further prepared on the silicon oxide tunneling layer.

[0101] 4) Localization of the doped film layer 4.

[0102] A mask is prepared on the surface of the doped film layer 4 using a screen printing mask, and the mask does not react with the alkaline solution; then the doped film layer 4 is corroded using a tetramethylammonium hydroxide solution; the doped film layer 4 outside the first electrode region is removed, and the passivation tunneling layer 3 is exposed; then it is cleaned using a hydrochloric acid solution and deionized water.

[0103] 5) Preparation of the first dielectric film layer 5 and the second dielectric film layer 6.

[0104] Enhanced plasma chemical vapor deposition is used to deposit a silicon nitride stack on the front of the battery to complete the preparation of the first dielectric film layer 5; enhanced plasma chemical vapor deposition is used to deposit a 5-10nm aluminum oxide layer on the back of the battery, and 80-120nm silicon nitride is deposited thereon to complete the preparation of the second dielectric film layer.

[0105] 6) Preparation of the first electrode and the second electrode.

[0106] A laser is used to make a hole in the first dielectric film layer 5, and the scanning method is to perform pulsed local laser irradiation treatment on the second dielectric film layer 6. The scanning direction is along the parallel line direction of the doping. The second dielectric film layer 6 forms a hole in the area irradiated by the laser spot, and no contact hole is formed in the unirradiated area. After the laser hole is opened in this contact hole area, the second dielectric film layer 6 is removed. The wavelength of the hole opening laser is 532nm, the spot size is 80um diameter circle, the scanning speed is 10000mm / s, and the frequency is 10kHz.

[0107] Conductive material is coated on the areas on the first and second sides of the battery after laser scanning. In this embodiment, we use screen printing to graphically apply the conductive paste. Silver paste is used as the paste for the first contact electrode 7 to fill the multiple parallel long strip first contact electrode 7 setting areas formed by scanning; a conductive paste that does not penetrate the first dielectric film layer 5 is used to fill the setting area of ​​the first connection electrode 8 whose setting direction is perpendicular to the first contact electrode 7. Aluminum paste is used as the paste for the second contact electrode 9 to fill the multiple parallel long strip second contact electrode 9 setting areas formed by scanning; silver paste is used as the paste for the second connection electrode 10 to fill the setting area of ​​the second connection electrode 10 whose setting direction is perpendicular to the second contact electrode 9.

[0108] 7) Perform metallization heat treatment. In this process, a chain sintering furnace can be used, and the sintering peak temperature is 850° C., which is the temperature of the surface of the silicon wafer measured. Finally, the aluminum conductive material is in direct contact with the substrate 1.

[0109] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A passivation contact structure, characterized in that: It includes a substrate, a first doped layer, a passivation tunneling layer, a doped film layer, a first dielectric film layer and a first electrode; The first doping layer is disposed on the first surface area of ​​the substrate; The passivation tunneling layer is disposed on at least a partial area of ​​the surface of the first doped layer away from the substrate; The doped film layer is disposed on a local area of ​​the surface of the passivation tunneling layer away from the first doped layer; The first dielectric film layer is disposed on the region formed by the first doped layer, the doped film layer and the surface of the passivation tunneling layer; the first dielectric film layer includes one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide and silicon carbide; The first electrode passes through the first dielectric film layer and contacts the doped film layer, and the areas of the doped film layer, the passivation tunneling layer, and the first doped layer gradually increase.

2. The passivation contact structure according to claim 1, characterized in that: The doped film layer includes a semiconductor material and a doping element, wherein the semiconductor material includes one or more of polycrystalline silicon and amorphous silicon; and the doping element includes one of a fifth main group element or a third main group element.

3. The passivation contact structure according to claim 2, characterized in that: The concentration of the doping element is greater than 1×10 15 Pieces / cm 3 .

4. The passivation contact structure according to claim 1, characterized in that: The thickness of the doped film layer is 5-300nm.

5. The passivation contact structure according to claim 1, characterized in that: The passivation tunneling layer includes one of silicon oxide, silicon oxynitride, amorphous silicon, aluminum oxide, titanium oxide, silicon nitride and silicon carbide.

6. The passivation contact structure according to claim 1 or 5, characterized in that: The thickness of the passivation tunneling layer is 0.1-5 nm.

7. The passivation contact structure according to claim 1, characterized in that: The square resistance of the first doped layer is 50 ohm / sq-300 ohm / sq.

8. A solar cell, characterized in that: The invention comprises a second dielectric film layer, a second electrode and a passivation contact structure according to any one of claims 1 to 7, wherein the second dielectric film layer is arranged on the second surface area of ​​the substrate, and the second electrode contacts the substrate through the second dielectric film layer.

9. The solar cell according to claim 8, characterized in that: The substrate in the passivation contact structure is a p-type silicon substrate, the first doped layer is an n-type doped layer, and the doped film layer is an n-type doped film layer.

10. The solar cell according to claim 9, characterized in that: The doped film layer includes a semiconductor material and a doping element, wherein the semiconductor material includes one or more of polycrystalline silicon and amorphous silicon; and the doping element includes one of the fifth main group elements.

11. The solar cell according to any one of claims 8 to 10, characterized in that: The second dielectric film layer includes one or more of silicon nitride, silicon oxide, silicon oxynitride, aluminum oxide, and silicon carbide.

12. A solar cell, characterized in that: The invention comprises a second doping layer, a second dielectric film layer, a second electrode and a passivation contact structure according to any one of claims 1 to 7, wherein the second doping layer is arranged on the second surface area of ​​the substrate, the second dielectric film layer is arranged on the second doping layer, and the second electrode contacts the second doping layer through the second dielectric film layer.

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