CN115020513B - Manufacturing method of interdigital back contact solar cell and manufactured interdigital back contact solar cell - Google Patents
Manufacturing method of interdigital back contact solar cell and manufactured interdigital back contact solar cell Download PDFInfo
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- 238000005498 polishing Methods 0.000 claims abstract description 91
- 238000009792 diffusion process Methods 0.000 claims abstract description 77
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 53
- 239000000758 substrate Substances 0.000 claims abstract description 47
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0224—Electrodes
- H01L31/022408—Electrodes for devices characterised by at least one potential jump barrier or surface barrier
- H01L31/022425—Electrodes for devices characterised by at least one potential jump barrier or surface barrier for solar cells
- H01L31/022441—Electrode arrangements specially adapted for back-contact solar cells
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
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- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/30—Deposition of compounds, mixtures or solid solutions, e.g. borides, carbides, nitrides
- C23C16/34—Nitrides
- C23C16/345—Silicon nitride
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/02—Details
- H01L31/0236—Special surface textures
- H01L31/02363—Special surface textures of the semiconductor body itself, e.g. textured active layers
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- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
- H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic Table
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Abstract
The invention relates to a manufacturing method of an interdigital back contact solar cell and the manufactured interdigital back contact solar cell, wherein the manufacturing method is used for carrying out double-sided polishing, primary slotting, front surface texturing, double-sided boron expansion, BSG (BSG) modification thinning, double-sided passivation, secondary windowing, back surface phosphorus expansion and screen printing on a silicon substrate to manufacture the interdigital back contact solar cell; the invention forms a concave-convex alternately arranged structure on the back of the battery through the grooves, so that P, N areas respectively formed in the concave-convex structure are physically isolated; meanwhile, the reserved thinned BSG layer is subjected to phosphorus expansion, so that phosphorus diffusion can be effectively promoted, a back N region and a heavily doped region can be formed, meanwhile, the reserved thinned BSG layer can play a passivation role, no additional process is required, the manufacturing method is relatively simple and convenient, the equipment requirement is not strict, and the method can be suitable for most of production lines existing in the field.
Description
Technical Field
The invention belongs to the field of solar cells, and particularly relates to a manufacturing method of an interdigital back contact solar cell and the manufactured interdigital back contact solar cell.
Background
With the increasing shortage of fossil energy in the world, it has become urgent to find alternative energy sources, wherein solar energy has become the focus of research as inexhaustible green energy. Through long development, the conversion efficiency of conventional PERC (Passivated Emitter Rear Cell, emitter and back passivation) cells has been approaching a limit, and various large cell manufacturers have also continuously tried to develop new technologies, such as TOPCon technology (Tunnel Oxide Passivating Contacts, tunnel oxide passivation contact), HJT technology (Heterojunction with Intrinsic Thin Layer, intrinsic thin film heterojunction), IBC (Interdigitated back contact, cross back contact) technology.
The IBC technology uses the front surface without grid lines, and positive and negative electrodes are marked on the back surface of the battery. The IBC cell structure can thus bring the following advantages: (1) The front surface is free of a main grid, so that the light receiving area is increased, and the short-circuit current density is increased; (2) The light trapping and surface passivation of the front surface can be optimized to the greatest extent without considering the front metal contact; (3) The positive electrode and the negative electrode are arranged on the back surface, the shading problem is not needed to be considered, and the metal electrode can be optimized to the greatest extent. Currently, IBC batteries, such as HBC technology and TBC technology, combined with HJT or TOPCon technology have been studied extensively, and the battery efficiency has been further improved. However, IBC technology has certain disadvantages due to the structure itself, such as that in order to prevent leakage, holes are needed at the back metal electrode and aligned with the diffusion region, and the formed P, N regions need not to affect each other as much as possible, and in addition, the back interdigital arrangement structure greatly improves the process complexity and difficulty of IBC, so that the manufacturing level of manufacturers is very tested.
CN112510105a discloses a high-efficiency solar cell and a preparation method thereof, in which a TOPCon tunneling structure is introduced into an IBC cell to select carriers, but the method has very high requirements for applicable laser so that the method can be matched with a process of locally etching a back surface tunneling layer, thereby forming a window to manufacture a doped region, but the laser is likely to have penetrated into a silicon substrate when etching the tunneling layer SiOx, destroying the lattice structure of a substrate to generate a large number of high recombination centers, and affecting the photoelectric conversion efficiency of the cell.
CN206907777U provides a full back electrode solar cell structure that reduces the leakage problem of P, N contact areas by adding front surface field doped layers to the front surface of an IBC cell and spacing the P-doped and N-doped regions by undoped regions to form an alternating arrangement; in the manufacturing method, phosphorus and boron are respectively injected twice by using a mask plate, and P, N areas on the back surface of a silicon substrate are formed by using a mask area and are alternately arranged, but the doping areas of the boron and the phosphorus are at the same level, and in the subsequent annealing, the lateral diffusion of the boron and the phosphorus cannot be avoided, so that the P/N junction area is influenced.
CN108987502a relates to an interdigitated back contact solar cell structure and a preparation method thereof, the invention adopts a coating mode to manufacture a P/N region on the back of a cell, firstly performs local diffusion of boron, then integrally grows SiOx on the back of a silicon substrate, and then performs high-precision laser windowing to reserve a phosphorus diffusion channel, no effective avoidance measures are taken for a possible dead layer in the whole diffusion process, and the subsequent phosphorus diffusion process under the method cannot avoid transverse diffusion, so that the P/N region can be directly contacted on the back surface of the silicon substrate.
In addition to the problems of the battery performance of the three patents, most battery sheet manufacturers in the industry still mainly produce PERC batteries at present, considering that the preparation process of the IBC batteries is quite complex, when the IBC batteries are converted into IBC production lines, the IBC batteries are eliminated due to lower production line connection degree of the IBC batteries, and the additional investment of equipment is increased by continuously adding HJT/TOPCon technology to the IBC batteries, so that the service life of the IBC battery production equipment is prolonged when new IBC battery development technology is searched, and the improvement of process combination and utilization rate is also the problem to be solved in IBC industrialization.
In view of the above problems, there is still a need to develop a new method for manufacturing IBC batteries, so that the back of the battery can realize effective isolation of P, N area without influence of independent diffusion into junction, and meanwhile, no damage is caused to the substrate, so that the IBC battery structure is further developed, and no severe technical process is added, so that the manufacturing process of the IBC battery can be matched with the existing industrial technology.
Disclosure of Invention
In view of the problems existing in the prior art, the invention aims to provide a manufacturing method of an interdigital back contact solar cell and the manufactured interdigital back contact solar cell, wherein the manufacturing method is used for carrying out double-sided polishing, primary slotting, front surface texturing, double-sided boron expansion, BSG (BSG) modification thinning, double-sided passivation, secondary windowing, back surface phosphorus expansion and screen printing on a silicon substrate to manufacture the interdigital back contact solar cell; according to the invention, the back of the battery is formed into a concave-convex alternate arrangement structure through one-time slotting, so that P, N areas respectively formed in the concave-convex structure are physically isolated; meanwhile, phosphorus diffusion is carried out through the reserved thinned BSG layer, phosphorus diffusion can be effectively promoted to form a back N region and a heavy doping region, meanwhile, the reserved thinned BSG layer can play a passivation effect, no additional process is required, the manufacturing method is relatively simple and convenient, the requirements on equipment are not strict, and the method can be suitable for most of production lines existing in the field.
To achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides a method for manufacturing an interdigital back contact solar cell, the method comprising the steps of:
(1) Preparing a silicon substrate and performing double-sided polishing;
(2) Windowing is carried out on the back surface of the polished silicon substrate to form a first groove and a non-windowed convex surface area, so that a staggered structure with alternately arranged concave and convex surfaces is formed on the back surface of the silicon substrate;
(3) Performing texturing on the front surface of the polished silicon substrate to form a texturing structure;
(4) Boron expansion is carried out on the texturing structure and the staggered structure to form a front BSG layer and a back BSG layer respectively;
(5) Modifying and thinning the front BSG layer and the back BSG layer to form a front thinned BSG layer and a back thinned BSG layer;
(6) Preparing passivation films on the front side thinned BSG layer and the back side thinned BSG layer to obtain a front side passivation layer and a back side passivation layer;
(7) Re-windowing is carried out on the corresponding position of the first groove or the non-windowed convex surface area on the back passivation layer to form a second groove, and the back thinning BSG layer is exposed; performing phosphorus expansion through the back thinning BSG layer in the second groove;
(8) Forming a negative electrode in the second groove through screen printing, so that ohmic contact is generated between the negative electrode and the doped region formed by phosphorus expansion; manufacturing a positive electrode, and enabling the positive electrode to penetrate through the back passivation layer to generate ohmic contact with the doped region formed by boron expansion, so as to obtain an interdigital back contact solar cell;
wherein, the step (2) and the step (3) are not in sequence.
The invention forms a concave-convex alternate arrangement structure on the back of the battery through the grooves, so that physical isolation is generated between a back P region (doped region formed by boron expansion) and a back N region (doped region formed by phosphorus expansion) which are respectively formed in the concave-convex structure, the influence caused by transverse diffusion in junction is weakened, and the phenomenon of electrode connection in electrode manufacturing can be avoided without insulating ink; meanwhile, the preserved thinned BSG layer is used for phosphorus expansion, so that the longitudinal diffusion of phosphorus can be effectively promoted to form an N region, the transverse diffusion of phosphorus can be restrained to a certain extent, the formed heavily doped region can have an effect similar to SE (selective emitter), the manufacturing method is relatively simple and convenient in process, has no strict requirements on equipment, and can be suitable for most of production lines existing in the field.
In the prior art, the back passivation layer is usually windowed to reserve the electrode position, and the BSG layer of the corresponding portion is completely removed and then phosphorus-diffused. The invention reserves the BSG layer formed on the back surface, and directly carries out phosphorus diffusion process through the thinned BSG layer after modification thinning, thus not only treating and removing the dead layer in the BSG in advance, but also leading the reserved BSG layer to promote the diffusion of phosphorus.
The inventors have systematically studied the diffusion of phosphorus through the BSG layer, and as is well known, when phosphorus doping is performed, the diffusion is initially a residual error distribution diffusion of infinite origin, and then a gaussian distribution diffusion of finite origin is performed. In the case of infinite source, the inventors compared the diffusion curve of phosphorus with and without the BSG layer, set the diffusion temperature to 830 ℃, the diffusion time to 40mins, and the BSG layer thickness to 25nm, as shown in fig. 5, it can be observed that when the diffusion depth is less than 0.2um, the diffusion of phosphorus is not significantly affected by the BSG layer with and without the BSG layer, and the surface sheet resistances are 56 Ω/sq and 53 Ω/sq, respectively; in fig. 5, there is a diffusion profile of boron during phosphorus diffusion, and it can be observed that the boron in BSG is rapidly reduced with junction depth before kinking, this is because a large amount of phosphorus accumulation reduces the diffusion rate of boron within the first 25nm depth, whereas when the depth exceeds 25nm, the diffusion rate of boron increases with the reduction of phosphorus element, and the concentration profile of both substantially satisfies the linear change.
For Gaussian distribution of finite sources, continuously comparing phosphorus source diffusion curves with and without a BSG layer, as shown in FIG. 6, setting the temperature to 920 ℃, the diffusion time to 100mins, and the BSG thickness to 73nm; limited POCl 3 The diffusion of phosphorus is not as pronounced kinking as in fig. 5. The difference of phosphorus expansion is obvious with or without BSG, and the surface concentration of phosphorus can reach 10 when the BSG layer is found 21 /cm 3 And without BSG is reduced to 10 20 /cm 3 The surface sheet resistance is 24 Ω/sq and 56 Ω/sq respectively, and the phosphorus diffusion concentration of the BSG layer is far higher than that of the BSG layer; the diffusion concentration of the phosphorus in the BSG layer is reduced very slowly along with the increase of the diffusion depth, so that the phosphorus can go deep into the silicon substrate without the BSG layer, and the phosphorus concentration cliff type becomes small rapidly after exceeding a certain depth. In fig. 6, there is also a corresponding boron diffusion curve in the BSG layer, the diffusion concentration rule of which is close to that of fig. 5, and in the thickness of the BSG layer, the diffusion rate of B is reduced due to the mass accumulation of phosphorus, so that the diffusion of phosphorus is not affected.
From the above, it can be seen that the BSG layer does not hinder the diffusion of phosphorus when the source is infinite, but in the subsequent high-temperature pushing stage, the BSG layer is helpful to the diffusion of phosphorus, based on this principle, the inventors propose the technical scheme of the present invention, and when the battery is manufactured, the thinned BSG layer is kept to perform phosphorus diffusion, so as to promote the diffusion of phosphorus to form an N region, and meanwhile, the formed heavily doped region can play the role of SE, so that the complexity of the process is simplified.
As a preferable technical scheme of the invention, the double-sided polishing in the step (1) comprises rough polishing, cleaning and then alkali polishing.
Preferably, the silicon substrate of step (1) comprises an N-type and/or P-type silicon wafer.
Preferably, the aqueous solution of coarse polishing used for coarse polishing comprises NaOH and/or KOH.
Preferably, the volume ratio of NaOH and/or KOH to water in the coarse polishing aqueous solution is (2-10): (300-380), for example, 2:300, 2:340, 2:380, 4:300, 4:340, 4:380, 6:300, 6:340, 8:380, 10:300, 10:340 or 10:380, etc., but not limited to the recited values, other non-recited values within the above-mentioned range of values are equally applicable.
Preferably, the rough polishing temperature is 69 to 79 ℃, for example 69 ℃, 71 ℃, 73 ℃, 75 ℃, 77 ℃, 79 ℃ or the like, and the time is 100 to 180 seconds, for example 100 seconds, 120 seconds, 140 seconds, 160 seconds or 180 seconds or the like, but the rough polishing temperature is not limited to the recited values, and other non-recited values within the above-mentioned numerical ranges are equally applicable.
Preferably, the aqueous alkali polishing solution used for alkali polishing comprises NaOH and/or KOH and alkali polishing additives.
It should be noted that the alkali polishing additive is commercially purchased, preferably, the types of bp171, bp63 or bp65 produced by Tuoban technology are adopted, and the main components of the alkali polishing additive comprise sodium benzoate, lauryl glucoside, sodium lactate, sodium diacetate, deionized water and the like, and of course, other alkali polishing additives can be selected and purchased by a person skilled in the art according to technical requirements and actual conditions.
Preferably, the volume ratio of NaOH and/or KOH, alkali polishing additive and water in the alkali polishing aqueous solution is (6-10): (4-6): (335-340), for example, 6:4:335, 6:4:338, 6:4:340, 7:4:335, 7:4:338, 7:4:340, 8:4:335, 8:4:338, 8:4:340, 9:4:335, 9:4:340, 10:4:335, 10:4:338, 10:4:340, 6:5:335, 6:5:338, 6:5:340, 7:5:335, 7:5:338, 7:5:340, 8:5:335, 8:5:338, 8:5:340, 9:5:335, 9:5:338, 9:5:340, 10:5:338, 10:5:340, 6:6:335, 6:6:340, 7:6:338, 7:6:6:340, 8:6:335, 8:6:6:335, 9:6:340, 9:9:9:9:338, 10:10:9:9:10:9:9:10, etc. the values are not limited to the ranges recited above, or the values of which are not recited as the values.
Preferably, the alkali polishing temperature is 65 to 80 ℃, for example 65 ℃, 68 ℃, 71 ℃, 74 ℃, 77 ℃, 80 ℃ or the like, and the time is 200 to 300 seconds, for example 200 seconds, 220 seconds, 240 seconds, 260 seconds, 280 seconds or 300 seconds or the like, but the alkali polishing temperature is not limited to the recited values, and other non-recited values within the above-mentioned numerical ranges are equally applicable.
As a preferable technical scheme of the invention, the windowing methods in the step (2) and the step (7) comprise laser windowing and/or mask corrosion.
Preferably, the depth of the first groove in the step (2) is 5 to 20 μm, for example, 5 μm, 8 μm, 11 μm, 14 μm, 17 μm or 20 μm, etc., and the width is 60 to 900 μm, for example, 60 μm, 100 μm, 300 μm, 500 μm, 700 μm, 800 μm or 900 μm, etc., but not limited to the values listed, and other values not listed in the above-mentioned value ranges are equally applicable.
Preferably, the width of the non-windowed convex surface region in the step (2) is 600 to 1500 μm, for example 600 μm, 900 μm, 1200 μm, 1400 μm or 1500 μm, etc., but is not limited to the values listed, and other non-listed values within the above-mentioned range are equally applicable.
Preferably, the width of the second groove in the step (7) is 20 to 50 μm, for example, 20 μm, 27 μm, 35 μm, 40 μm, 45 μm or 50 μm, etc., but not limited to the values listed, and other values not listed in the above-mentioned value ranges are equally applicable.
As a preferable technical scheme of the invention, the water solution for texturing used in the step (3) comprises NaOH and/or KOH and a texturing additive.
It should be noted that the texturing additive is commercially purchased, preferably, the model of TS52-V13, TS55-V42 or TS55-V67 produced by the invasive company is adopted, and the main components of the texturing additive comprise water, potassium sorbate, sodium acetate, defoamer, surfactant and the like, and of course, other texturing additives can be selected and purchased by those skilled in the art according to technical needs and actual conditions.
Preferably, the volume ratio of NaOH and/or KOH, the texturing additive and water in the aqueous solution is (3-13): (0.3-4.3): (326-346), for example, 3:0.3:326, 3:0.3:336, 3:0.3:346, 8:0.3:326, 8:0.3:336, 8:0.3:346, 13:0.3:326, 13:0.3:336, 13:0.3:346, 3:2.3:326, 3:2.3:336, 3:2.3:346, 8:2.3:326, 8:2.3:336, 8:2.3:326, 13:2.3:336, 13:2.3:326, 3:4.3:336, 3:4.3:346, 8:4.3:326, 8:4:4:4:3:346, 13:4.3:346, and the like are not limited to the above ranges, but the values are not limited to the ranges or the ranges of the values listed above.
Preferably, the temperature of the texturing is 370 to 470 ℃, such as 370 ℃, 390 ℃, 410 ℃, 430 ℃, 450 ℃, 470 ℃ or the like, and the time is 60 to 100s, such as 60s, 70s, 80s, 90s, 95s, 100s or the like, but the texturing method is not limited to the listed values, and other non-listed values in the above-mentioned numerical ranges are equally applicable.
As a preferable technical scheme of the invention, the boron diffusion in the step (4) comprises the steps of pre-depositing and then performing propulsion diffusion.
Preferably, the pre-deposition temperature is 850 to 950 ℃, such as 850 ℃, 870 ℃, 890 ℃, 910 ℃, 930 ℃, 950 ℃ or the like, and the time is 18 to 50min, such as 18min, 25min, 30min, 40min or 50min or the like, but the pre-deposition temperature is not limited to the recited values, and other non-recited values within the above-recited value range are equally applicable.
Preferably, the pre-deposited boron source comprises B (CH 3 O) 3 、C 9 H 21 BO 3 、BCl 3 Or BBr 3 Any one or a combination of at least two, preferably BBr 3 Typical but non-limiting examples of such combinations include B (CH 3 O) 3 And C 9 H 21 BO 3 Is a combination of (B) (CH) 3 O) 3 With BCl 3 Is a combination of (B) (CH) 3 O) 3 And BBr 3 Combination of C 9 H 21 BO 3 With BCl 3 Combination of C 9 H 21 BO 3 And BBr 3 Or BCl of (C) 3 And BBr 3 Is a combination of (a) and (b).
Incidentally, B (CH) 3 O) 3 C (C) 9 H 21 BO 3 Carbon with strong reducibility is generated in the reaction process, so that the quartz device is easy to corrode, the saturated vapor pressure at room temperature is high, the volatility is high, and BCl 3 Is gaseous at room temperature and is not beneficial to safe use, therefore, BBr is preferred in the invention 3 As a conventional boron source.
Preferably, the flow rate of the pre-deposited oxygen gas is 100 to 3000sccm, for example, 100sccm, 1000sccm, 1500sccm, 2000sccm, 2500sccm, 3000sccm, or the like, but the flow rate is not limited to the recited values, and other values not recited in the above-described range are equally applicable.
Preferably, the flow rate of the source-carrying nitrogen gas for the pre-deposition is 200-1200 sccm, for example, 200sccm, 400sccm, 600sccm, 800sccm, 1000sccm, 1200sccm, etc., but is not limited to the recited values, and other non-recited values within the above-mentioned range are equally applicable.
Preferably, the flow rate of the main nitrogen gas for the pre-deposition is 2000 to 20000sccm, for example, 2000sccm, 6000sccm, 10000sccm, 15000sccm, 20000sccm, etc., but is not limited to the recited values, and other non-recited values within the above-recited range are equally applicable.
Preferably, the temperature of the diffusion by the propulsion is 950 to 1100 ℃, for example 950 ℃, 980 ℃, 1010 ℃, 1040 ℃, 1070 ℃, 1100 ℃ or the like, and the time is 30 to 50min, for example 30min, 35min, 40min, 45min, 50min or the like, but the diffusion is not limited to the listed values, and other values not listed in the above-mentioned value ranges are equally applicable.
Preferably, the boron diffusion in step (4) has a doping concentration of 10 19 ～10 21 cm -3 For example 10 19 cm -3 、5×10 19 cm -3 、10 20 cm -3 、5×10 20 cm -3 Or 10 21 cm -3 And the like, but are not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
Preferably, the thickness of the front surface BSG layer and the back surface BSG layer in the step (4) is 30 to 90nm, for example, 30nm, 40nm, 50nm, 60nm, 70nm, 75nm, 80nm, 85nm, or 90nm, but not limited to the above-mentioned values, and other values not mentioned in the above-mentioned value ranges are equally applicable.
As a preferred embodiment of the present invention, the etching cleaning solution modified and thinned in the step (5) includes 20-40 wt% of HF solution, such as 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, etc., but is not limited to the listed values, and other non-listed values within the above-mentioned range are equally applicable.
Preferably, the time for the modification and thinning in the step (5) is 50 to 250s, for example, 50s, 80s, 120s, 160s, 200s, 220s or 250s, but the present invention is not limited to the listed values, and other non-listed values in the above-mentioned value range are equally applicable.
Preferably, in the step (5), the thicknesses of the front-side thinned BSG layer and the back-side thinned BSG layer are each 10 to 40nm, for example, 10 μm, 20 μm, 30 μm, 40 μm, or the like, but the thicknesses are not limited to the values listed, and other values not listed in the above-mentioned value ranges are equally applicable.
As a preferable technical scheme of the invention, in the step (6), the materials of the front passivation layer and the back passivation layer both comprise SiN x 。
Preferably, the method for preparing the passivation film in the step (6) includes a PECVD method.
Preferably, the plasma rf power of the PECVD method is 9000 to 20000W, for example 9000W, 12000W, 15000W, 17000W, 20000W, or the like, but is not limited to the values listed, and other values not listed in the above-mentioned value range are equally applicable.
The temperature of the PECVD method is preferably 450-500 ℃, such as 450 ℃, 460 ℃, 470 ℃, 480 ℃, 490 ℃, or 500 ℃, but is not limited to the recited values, and other non-recited values within the above-mentioned range are equally applicable.
Preferably, the reaction gas of the PECVD method is SiH 4 And NH 3 。
Preferably, the SiH 4 And NH 3 The flow ratio of (2) is 1 (4-10), for example, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10, etc., but is not limited to the listed numbersOther values not listed in the above ranges are equally applicable.
Preferably, the SiH 4 The flow rate of (C) is 500 to 2300sccm, for example, 500sccm, 600sccm, 700sccm, 800sccm, 900sccm, 1000sccm, 1100sccm, 1200sccm, 1300sccm, 1400sccm, 1500sccm, 1600sccm, 1700sccm, 1800sccm, 1900sccm, 2000sccm, 2100sccm, 2200sccm, 2300sccm, etc., but the flow rate is not limited to the above-mentioned values, and other values not mentioned in the above-mentioned numerical ranges are applicable.
The PECVD method is preferably performed at 220-240 Pa, for example 220Pa, 225Pa, 230Pa, 235Pa or 240Pa, but is not limited to the recited values, and other non-recited values within the above-mentioned ranges are equally applicable.
Preferably, the front passivation layer and the back passivation layer in the step (6) have thicknesses of 70 to 90nm, for example, 70 μm, 75 μm, 80 μm, 85 μm or 90 μm, but the thicknesses are not limited to the values listed, and other values not listed in the above-mentioned numerical ranges are equally applicable.
Preferably, the refractive index of the front passivation layer and the back passivation layer in the step (6) is 1.98-2.03, for example, 1.98, 1.99, 2, 2.01, 2.02 or 2.03, but not limited to the values listed, and other values not listed in the above-mentioned value ranges are equally applicable.
As a preferable technical scheme of the invention, the phosphorus-expanded reaction gas in the step (8) is POCl 3 And O 2 。
Preferably, the POCl 3 And O 2 The flow ratio of (1-2) is 1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1 or 2:1, etc., but is not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
Preferably, the POCl 3 The flow rate of (C) is 500 to 2000sccm, for example, 500sccm, 700sccm, 900sccm, 1100sccm, 1300sccm, 1500sccm, 1700sccm, 1900sccm, 2000sccm, etc., but the flow rate is not limited to the values listed, and other values not listed in the above-mentioned numerical ranges are applicable.
Preferably, the phosphorus expansion in step (8) is performed at 50 to 150Pa, for example, 50Pa, 70Pa, 90Pa, 110Pa, 130Pa, 150Pa, or the like, but the phosphorus expansion is not limited to the recited values, and other non-recited values within the above-recited range are equally applicable.
Preferably, the temperature of the phosphorus expansion in the step (8) is 770 to 830 ℃, for example 770 to 780 ℃, 790 ℃, 800 ℃, 810 ℃, 820 ℃, 830 ℃, etc., and the time is 150 to 250s, for example 150s, 170s, 190s, 210s, 230s, 250s, etc., but the phosphorus expansion is not limited to the listed values, and other non-listed values within the above-mentioned range are equally applicable.
Preferably, the phosphorus diffusion of step (8) has a doping concentration of 10 19 ～10 21 cm -3 For example 10 19 cm -3 、5×10 19 cm -3 、10 20 cm -3 、5×10 20 cm -3 Or 10 21 cm -3 And the like, but are not limited to the recited values, and other non-recited values within the above-recited ranges are equally applicable.
Preferably, the material of the negative electrode in step (9) includes silver.
Preferably, the material of the positive electrode in step (9) includes aluminum.
As a preferred technical scheme of the invention, the method comprises the following steps:
(1) Preparing an N-type and/or P-type silicon wafer as a silicon substrate and performing double-sided polishing, firstly performing rough polishing for 100-180 s at 69-79 ℃ by using a rough polishing aqueous solution, cleaning by using water, and then performing alkali polishing for 200-300 s at 65-80 ℃ by using an alkali polishing aqueous solution; the volume ratio of NaOH and/or KOH to water in the coarse polishing aqueous solution is (2-10) (300-380); the volume ratio of NaOH and/or KOH and alkali polishing additive to water in the alkali polishing aqueous solution is (6-10): 4-6): 335-340;
(2) Using a laser windowing and/or mask etching method to window the back surface of the polished silicon substrate to form a first groove with the depth of 5-20 mu m and the width of 60-900 mu m and a non-windowed convex surface area with the width of 600-1500 mu m, so that the back surface of the silicon substrate forms a staggered structure with concave-convex alternately arranged;
(3) Using a texturing water solution to perform texturing on the front surface of the silicon substrate at 370-470 ℃ for 60-100 s to form a texturing structure; the volume ratio of NaOH and/or KOH and the wool making additive to water in the wool making aqueous solution is (3-13) (0.3-4.3) (326-346);
(4) The doping concentration of the wool making structure and the staggered structure is 10 19 ～10 21 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 30-90 nm respectively; the boron diffusion comprises the steps of pre-depositing for 18-50 min at 850-950 ℃ and then performing pushing diffusion for 30-50 min at 950-1100 ℃; the pre-deposited boron source comprises B (CH 3 O) 3 、C 9 H 21 BO 3 、BCl 3 Or BBr 3 Any one or a combination of at least two, preferably BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 100-3000 sccm; the flow of the pre-deposited source carrying nitrogen is 200-1200 sccm; the flow rate of the pre-deposited main nitrogen is 2000-20000 sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 20-40 wt% for 50-250 s to form a front thinned BSG layer and a back thinned BSG layer with the thickness of 10-40 nm;
(6) SiN is carried out on the front surface thinning BSG layer and the back surface thinning BSG layer by adopting a PECVD method x Coating to obtain a front passivation layer and a back passivation layer with the thickness of 70-90 nm and the refractive index of 1.98-2.03; the plasma radio frequency power of the PECVD method is 9000-20000W, the temperature is 450-500 ℃, and the reaction gas is SiH 4 And NH 3 And SiH 4 And NH 3 The flow ratio of (2) is 1 (4-10), wherein SiH 4 The flow rate of the catalyst is 500-2300 sccm, and the PECVD method is carried out under 220-240 Pa;
(7) Re-windowing the corresponding position of the first groove or the non-windowed convex surface region on the back passivation layer to form a second groove with the width of 20-50 mu m, and exposing the back thinning BSG layer; then carrying out phosphorus expansion for 150-250 ℃ at 770-830 ℃ through the back thinning BSG layer in the second grooves, the doping concentration of phosphorus is 10 19 ～10 21 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (1-2): 1, wherein the POCl 3 The flow rate of the water is 500-2000 sccm; the phosphorus expansion is carried out under 50-150 Pa;
(8) Forming a silver electrode in the second groove as a negative electrode through screen printing, so that ohmic contact is generated between the negative electrode and the doped region formed by phosphorus expansion; an aluminum electrode is manufactured as a positive electrode, and the positive electrode passes through the back passivation layer and generates ohmic contact with the doped region formed by boron expansion, so that an interdigital back contact solar cell is obtained;
wherein, the step (2) and the step (3) are not in sequence.
In a second aspect, the invention provides an interdigital back contact solar cell obtained by the manufacturing method according to the first aspect.
Compared with the prior art, the invention has at least the following beneficial effects:
(1) According to the invention, the back of the battery is in a structure with alternately arranged concave and convex surfaces, so that P, N areas respectively formed in the concave and convex structures are physically isolated and separated, the influence of a diffusion process on a nearby area can be effectively prevented, and the phenomenon of connecting positive and negative electrodes is avoided;
(2) According to the invention, the BSG layer is modified and thinned, so that on one hand, a dead layer can be removed, on the other hand, phosphorus diffusion can be effectively promoted to form an N region by carrying out phosphorus diffusion on the thinned BSG layer, and meanwhile, the formed heavily doped region can have an SE-like effect, so that the promotion of the carrier separation effect in the battery is facilitated;
(3) The manufacturing method has the advantages of relatively simple and convenient process, low requirement on equipment and suitability for most of production lines existing in the field.
Drawings
Fig. 1 is a schematic structural diagram of an interdigital back contact solar cell obtained in embodiment 1 of the present invention;
fig. 2 is a process schematic of the method for manufacturing the interdigital back contact solar cell according to embodiment 1 of the present invention;
fig. 3 is a schematic structural diagram of an interdigital back contact solar cell obtained in embodiment 2 of the present invention;
fig. 4 is a process schematic of the method for manufacturing the interdigital back contact solar cell according to embodiment 2 of the present invention;
in the figure: 1-silicon substrate, 21-front thinned BSG layer, 22-back thinned BSG layer, 31-front passivation film, 32-back passivation film, 4-negative electrode, 5-positive electrode;
FIG. 5 is an unlimited phosphorus source POCl 3 A diffusion curve test pattern with and without a BSG layer;
FIG. 6 is a limited phosphorus source POCl 3 Diffusion curve test patterns with and without BSG layer.
Detailed Description
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings. It will be apparent to those skilled in the art that the examples are merely to aid in understanding the invention and are not to be construed as a specific limitation thereof.
Example 1
The embodiment provides a manufacturing method of an interdigital back contact solar cell, a process schematic diagram of the corresponding manufacturing method is shown in fig. 2, a structure schematic diagram of the obtained solar cell is shown in fig. 1, and the manufacturing method comprises the following steps:
(1) Preparing an N-type silicon wafer with resistivity of 1 omega cm and thickness of 150 mu m as a silicon substrate 1, performing double-sided polishing, performing rough polishing for 140s at 74 ℃ by using a rough polishing aqueous solution, cleaning by using water, and performing alkali polishing for 250s at 73 ℃ by using an alkali polishing aqueous solution; the volume ratio of NaOH to water in the coarse polishing aqueous solution is 6:340; the volume ratio of NaOH to alkali polishing additive (bp 63) to water in the alkali polishing aqueous solution is 6:4:340;
(2) Using a laser windowing method to window the back surface of the polished silicon substrate 1 to form a first groove with the depth of 10 mu m and the width of 600 mu m and a non-windowed convex surface area with the width of 1100 mu m, so that the back surface of the silicon substrate 1 forms a staggered structure with alternately arranged concave and convex surfaces;
(3) Texturing the front surface of the silicon substrate 1 for 80s at 420 ℃ by using a texturing water solution to form a texturing structure; naOH and a texturing additive (TS 55-V67) in the texturing aqueous solution and water are mixed according to the volume ratio of 6:2:330;
(4) The doping concentration of the wool making structure and the staggered structure is 10 20 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 70nm respectively; the boron diffusion comprises the steps of pre-depositing for 35min at 900 ℃ and then performing pushing diffusion for 40min at 1000 ℃; the pre-deposited boron source is BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 1000sccm; the flow of the pre-deposited source carrying nitrogen is 1400sccm; the flow of the pre-deposited main nitrogen is 10000sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 30wt% for 150s to form a front thinned BSG layer 21 and a back thinned BSG layer 22 with the thickness of 25 nm;
(6) Setting SiH by PECVD method 4 The flow rate of (2) is 1400sccm, and SiH is controlled 4 And NH 3 The flow ratio of (2) is 1 (4-10), the air pressure is 220-240 Pa, the plasma radio frequency power is 14000W, the PECVD temperature is 450 ℃, siN is carried out on the front side thinned BSG layer 21 and the back side thinned BSG layer 22 x Coating to obtain a front passivation film 31 and a back passivation layer 32 which are both 80nm thick and 2 in refractive index;
(7) Re-windowing at a corresponding position of the first groove on the back passivation layer 32 to form a second groove with a width of 35 μm, and exposing the back thinned BSG layer 22; then phosphorus expansion is carried out for 200s at 800 ℃ through the back thinning BSG layer 22 in the second groove, so that the doping concentration of phosphorus is 10 20 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1.4:1, wherein the POCl is 3 The flow rate of (2) is 1600sccm; the phosphorus expansion is carried out under 80 Pa;
(8) Forming a silver electrode in the second groove as a negative electrode 4 by screen printing, so that the negative electrode 4 and the doped region formed by phosphorus expansion generate ohmic contact; an aluminum electrode is manufactured as a positive electrode 5, and the positive electrode 5 passes through the back passivation layer 32 to generate ohmic contact with the doped region formed by boron diffusion, so that an interdigital back contact solar cell is obtained;
wherein, the step (2) and the step (3) are not in sequence.
Example 2
The embodiment provides a manufacturing method of an interdigital back contact solar cell, which comprises the following steps:
(1) Preparing an N-type silicon wafer with resistivity of 1 omega cm and thickness of 150 mu m as a silicon substrate, performing double-sided polishing, performing rough polishing for 100s at 69 ℃ by using a rough polishing aqueous solution, cleaning by using water, and performing alkaline polishing for 200s at 65 ℃ by using an alkaline polishing aqueous solution; the volume ratio of NaOH to water in the coarse polishing aqueous solution is 2:300; the volume ratio of NaOH to alkali polishing additive (bp 65) to water in the alkali polishing aqueous solution is 8:5:338;
(2) Using a laser windowing method to window the back surface of the polished silicon substrate to form a first groove with the depth of 5 mu m and the width of 200 mu m and a non-windowed convex surface area with the width of 600 mu m, so that the back surface of the silicon substrate forms a staggered structure with concave and convex alternately arranged;
(3) Using a texturing water solution to perform texturing on the front surface of the silicon substrate for 60s at 370 ℃ to form a texturing structure; naOH and a texturing additive (TS 55-V42) in the texturing aqueous solution and water are mixed in a volume ratio of 3:0.3:326;
(4) The doping concentration of the wool making structure and the staggered structure is 10 19 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 30nm respectively; the boron diffusion comprises the steps of pre-depositing for 18min at 850 ℃ and then performing pushing diffusion for 30min at 950 ℃; the pre-deposited boron source is BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 100sccm; the flow of the pre-deposited source carrying nitrogen is 200sccm; the flow rate of the pre-deposited main nitrogen is 2000sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 20wt% for 50s to form a front BSG layer and a back BSG layer with the thickness of 10 nm;
(6) Setting SiH by PECVD method 4 The flow rate of (2) is 500sccm, and SiH is controlled 4 And NH 3 The flow ratio of (2) is 1 (4-10), the air pressure is 220-240 Pa, the plasma radio frequency power is 9000W, the PECVD temperature is 450 ℃, siN is carried out on the front side thinned BSG layer and the back side thinned BSG layer x Coating to obtain a front passivation layer and a back passivation layer which are 70nm thick and 1.98 in refractive index;
(7) Windowing again at the corresponding position of the first groove on the back passivation layer to form a second groove with the width of 20 mu m, and exposing the back thinning BSG layer; then carrying out phosphorus expansion for 150s at 770 ℃ through the back thinning BSG layer in the second groove to ensure that the doping concentration of phosphorus is 10 19 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1:1, wherein the POCl is 3 The flow rate of (2) is 500sccm; the phosphorus expansion is carried out at 50 Pa;
(8) Forming a silver electrode in the second groove to serve as a negative electrode through screen printing, so that ohmic contact is generated between the negative electrode and a doped region formed by phosphorus expansion; an aluminum electrode is manufactured as a positive electrode, and the positive electrode passes through the back passivation layer and generates ohmic contact with the doped region formed by boron expansion, so that an interdigital back contact solar cell is obtained;
Wherein, the step (2) and the step (3) are not in sequence.
Example 3
The embodiment provides a manufacturing method of an interdigital back contact solar cell, which comprises the following steps:
(1) Preparing an N-type silicon wafer with resistivity of 1 omega cm and thickness of 150 mu m as a silicon substrate, performing double-sided polishing, performing rough polishing for 180s at 79 ℃ by using a rough polishing aqueous solution, cleaning by using water, and performing alkaline polishing for 300s at 80 ℃ by using an alkaline polishing aqueous solution; the volume ratio of NaOH to water in the coarse polishing aqueous solution is 10:380; the volume ratio of NaOH to alkali polishing additive (bp 171) to water in the alkali polishing aqueous solution is 10:6:380;
(2) Using a laser windowing method to window the back surface of the polished silicon substrate to form a first groove with the depth of 30 mu m and the width of 900 mu m and a non-windowed convex surface area with the width of 1500 mu m, so that the back surface of the silicon substrate forms a staggered structure with concave and convex alternately arranged;
(3) Using a texturing water solution to perform texturing on the front surface of the silicon substrate for 100s at 470 ℃ to form a texturing structure; naOH and a texturing additive (TS 52-V13) in the texturing water solution and water are mixed according to the volume ratio of 13:4.3:346;
(4) The doping concentration of the wool making structure and the staggered structure is 10 21 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 90nm respectively; the boron diffusion comprises the steps of pre-depositing for 50min at 950 ℃ and then performing pushing diffusion for 50min at 1100 ℃; the pre-deposited boron source is BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 3000sccm; the flow of the pre-deposited source carrying nitrogen is 2000sccm; the flow rate of the pre-deposited main nitrogen is 20000sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 40wt% for 250s to form a front BSG layer and a back BSG layer with the thickness of 40 nm;
(6) Setting SiH by PECVD method 4 The flow rate of (2) is 2300sccm, and SiH is controlled 4 And NH 3 The flow ratio of (2) is 1 (4-10), the air pressure is 220-240 Pa, the plasma radio frequency power is 20000W, the PECVD temperature is 500 ℃, siN is carried out on the front side thinned BSG layer and the back side thinned BSG layer x Coating to obtain a front passivation layer and a back passivation layer which are both 90nm thick and 2.03 in refractive index;
(7) Windowing again at the corresponding position of the first groove on the back passivation layer to form a second groove with the width of 50 mu m, and exposing the back thinning BSG layer; then carrying out phosphorus expansion for 250s at 830 ℃ through the back thinning BSG layer in the second groove to ensure that the doping concentration of phosphorus is as follows 10 21 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) to (1), wherein the POCl is as follows 3 The flow rate of (2) is 3000sccm; the phosphorus expansion is carried out at 150 Pa;
(8) Forming a silver electrode in the second groove to serve as a negative electrode through screen printing, so that ohmic contact is generated between the negative electrode and a doped region formed by phosphorus expansion; an aluminum electrode is manufactured as a positive electrode, and the positive electrode passes through the back passivation layer and generates ohmic contact with the doped region formed by boron expansion, so that an interdigital back contact solar cell is obtained;
wherein, the step (2) and the step (3) are not in sequence.
Example 4
The embodiment provides a manufacturing method of an interdigital back contact solar cell, a process schematic diagram of the corresponding manufacturing method is shown in fig. 4, a structure schematic diagram of the obtained solar cell is shown in fig. 3, and compared with embodiment 1, the manufacturing method is different in that in step (7), secondary windowing is performed at a corresponding position of the non-windowed convex surface region, that is, the manufacturing method includes the following steps:
(1) Preparing a P-type silicon wafer with resistivity of 1 omega cm and thickness of 150 mu m as a silicon substrate 1, performing double-sided polishing, performing rough polishing for 140s at 74 ℃ by using a rough polishing aqueous solution, cleaning by using water, and performing alkaline polishing for 250s at 73 ℃ by using an alkaline polishing aqueous solution; the volume ratio of NaOH to water in the coarse polishing aqueous solution is 6:340; the volume ratio of NaOH to alkali polishing additive (bp 63) to water in the alkali polishing aqueous solution is 6:4:340;
(2) Using a mask etching method to window the back surface of the polished silicon substrate 1 to form a first groove with the depth of 10 mu m and the width of 1100 mu m and a 600 mu m non-windowed convex surface area, so that the back surface of the silicon substrate 1 forms a staggered structure with concave and convex alternately arranged;
(3) Texturing the front surface of the silicon substrate 1 for 80s at 420 ℃ by using a texturing water solution to form a texturing structure; naOH and a texturing additive (TS 55-V67) in the texturing aqueous solution and water are mixed according to the volume ratio of 6:2:330;
(4) The doping concentration of the wool making structure and the staggered structure is 10 20 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 70nm respectively; the boron diffusion comprises the steps of pre-depositing for 35min at 900 ℃ and then performing pushing diffusion for 40min at 1000 ℃; the pre-deposited boron source is BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 1000sccm; the flow of the pre-deposited source carrying nitrogen is 800sccm; the main nitrogen flow of the pre-deposition is 10000sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 30wt% for 150s to form a front thinned BSG layer 21 and a back thinned BSG layer 22 with the thickness of 25 nm;
(6) Setting SiH by PECVD method 4 The flow rate of (2) is 1400sccm, and SiH is controlled 4 And NH 3 The flow ratio of (2) is 1 (4-10), the air pressure is 220-240 Pa, the plasma radio frequency power is 14000W, the PECVD temperature is 450 ℃, siN is carried out on the front side thinned BSG layer 21 and the back side thinned BSG layer 22 x Coating to obtain a front passivation film 31 and a back passivation layer 32 which are both 80nm thick and 2 in refractive index;
(7) Windowing is carried out at a corresponding position of the non-windowed convex surface region on the back passivation layer 32, so as to form a second groove with the width of 35 mu m, and the back thinning BSG layer 22 is exposed; then phosphorus expansion is carried out for 200s at 800 ℃ through the back thinning BSG layer 22 in the second groove, so that the doping concentration of phosphorus is 10 20 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1.4:1, wherein the POCl is 3 The flow rate of (2) is 1600sccm; the phosphorus expansion is carried out under 80 Pa;
(8) Forming a silver electrode in the second groove as a negative electrode 4 by screen printing, so that the negative electrode 4 and the doped region formed by phosphorus expansion generate ohmic contact; an aluminum electrode is manufactured as a positive electrode 5, and the positive electrode 5 passes through the back passivation layer 32 to generate ohmic contact with the doped region formed by boron diffusion, so that an interdigital back contact solar cell is obtained;
Wherein, the step (2) and the step (3) are not in sequence.
Comparative example 1
The present comparative example provides a method for manufacturing an interdigital back contact solar cell, which is different from embodiment 1, in that in the method for manufacturing the interdigital back contact solar cell, in step (7), the back surface thinned BSG layer in the second groove is completely removed and then phosphorus expansion is performed, namely, in step (7), the method is as follows: windowing is carried out again at the corresponding position of the first groove on the back passivation layer, and the corresponding back thinning BSG is removed completely while the back passivation layer is removed, so that a second groove with the width of 35 mu m is formed; then directly carrying out phosphorus expansion for 240s at 800 ℃ through the second groove to ensure that the doping concentration of phosphorus is 10 20 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1.4:1, wherein the POCl is 3 The flow rate of (2) is 1600sccm; the phosphorus expansion is carried out under 80 Pa;
other conditions of this comparative example were exactly the same as those of example 1 except for the above adjustment.
Comparative example 2
The present comparative example provides a method of manufacturing an interdigital back contact solar cell, which is different from embodiment 1 in that the method of manufacturing does not form a staggered structure in which irregularities are alternately arranged on the back surface of the silicon substrate, that is, the method of manufacturing includes the steps of:
(1') preparing an N-type silicon wafer with resistivity of 1 omega cm and thickness of 150 mu m as a silicon substrate, performing double-sided polishing, performing rough polishing for 140s at 74 ℃ by using a rough polishing aqueous solution, cleaning by using water, and performing alkali polishing for 250s at 73 ℃ by using an alkali polishing aqueous solution; the volume ratio of NaOH to water in the coarse polishing aqueous solution is 6:340; the volume ratio of NaOH to alkali polishing additive (bp 63) to water in the alkali polishing aqueous solution is 6:4:340;
(2') texturing the front surface of the silicon substrate for 80s at 420 ℃ by using a texturing water solution to form a texturing structure; naOH and a texturing additive (TS 55-V67) in the texturing aqueous solution and water are mixed according to the volume ratio of 6:2:330;
(3') carrying out doping concentration of 10 on the texturing structure and the staggered structure 20 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 70nm respectively; the boron diffusion comprises the steps of pre-depositing for 35min at 900 ℃ and then performing pushing diffusion for 40min at 1000 ℃; the pre-deposited boron source is BBr 3 The method comprises the steps of carrying out a first treatment on the surface of the The flow rate of the pre-deposited oxygen is 1000sccm; the flow of the pre-deposited source carrying nitrogen is 800sccm; the main nitrogen flow of the pre-deposition is 10000sccm;
(4') modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 30wt% for 150s to form a front BSG layer and a back BSG layer with the thickness of 25 nm;
(5') setting SiH by PECVD method 4 The flow rate of (2) is 500sccm, and SiH is controlled 4 And NH 3 The flow ratio of (2) is 1 (4-10), the air pressure is 220-240 Pa, the plasma radio frequency power is 9000W, the PECVD temperature is 450 ℃, siN is carried out on the front side thinned BSG layer and the back side thinned BSG layer x Coating to obtain a front passivation layer and a back passivation layer which are 70nm thick and 1.98 in refractive index;
(6') windowing on the back passivation layer to form a groove with the width of 35 mu m, and exposing the back thinning BSG layer; then carrying out phosphorus expansion for 200s at 800 ℃ through the back thinning BSG layer in the groove to ensure that the doping concentration of phosphorus is 10 20 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1.4:1, wherein the POCl is 3 The flow rate of (2) is 1600sccm; the phosphorus expansion is carried out under 80 Pa;
(7') forming a silver electrode as a negative electrode in the groove by screen printing, so that the negative electrode and the doped region formed by phosphorus expansion are in ohmic contact; and manufacturing an aluminum electrode as a positive electrode, and enabling the positive electrode to pass through the back passivation layer to generate ohmic contact with the doped region formed by the boron diffusion, so as to obtain the interdigital back contact solar cell.
Comparative example 3
The present comparative example provides a method for manufacturing an interdigital back contact solar cell, which is different from comparative example 2 in that in step (6'), the back surface thinned BSG layer in the groove is completely removed and then phosphorus expansion is performed, namely, step (6) is: windowing on the back passivation layer, removing the BSG layer while removing the back passivation layer, and forming a groove with the width of 35 mu m; then phosphorus expansion is carried out for 200s at 800 ℃ through the groove, so that the doping concentration of phosphorus is 10 20 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (2) is 1.4:1, wherein the POCl is 3 The flow rate of (2) is 1600sccm; the phosphorus expansion is carried out under 80 Pa;
other conditions of this comparative example were exactly the same as those of comparative example 2 except for the above adjustment.
The solar cells obtained in the above examples and comparative examples were tested, and the results are shown in table 1.
TABLE 1
| Project | Uoc(V) | Isc(A) | FF(％) | NCell |
| Example 1 | 0.6963 | 13.745 | 81.31 | 23.57 |
| Example 2 | 0.6961 | 13.741 | 81.24 | 23.54 |
| Example 3 | 0.6958 | 13.747 | 81.25 | 23.54 |
| Example 4 | 0.6962 | 13.743 | 81.32 | 23.57 |
| Comparative example 1 | 0.6954 | 13.722 | 81.17 | 23.46 |
| Comparative example 2 | 0.6959 | 13.735 | 80.97 | 23.44 |
| Comparative example 3 | 0.6951 | 13.729 | 81.02 | 23.42 |
As can be seen from table 1: the solar cells obtained in embodiments 1-4 of the present invention are improved in Uoc, isc and FF, thereby resulting in improved efficiency; comparing example 1 with comparative example 1, it was found that the solar cell obtained in comparative example 1 retained the P/N region physical isolation structure with the back surface being rugged, but the cell conversion efficiency was still reduced by 0.11% because the depth and concentration of phosphorus expansion were greatly affected by performing phosphorus expansion after the BSG layer was completely removed in comparative example 1; in the comparative example 2, the BSG layer is remained for phosphorus expansion, but the back side is not provided with a staggered structure with concave-convex alternating arrangement, and the P/N area on the back side is not effectively and physically isolated, so that the separation effect on carriers is greatly limited compared with the comparative example 1, and therefore, the conversion efficiency is 0.13% lower than that of the comparative example 1, and is 0.02% lower than that of the comparative example 1; the solar cell obtained in the comparative example 3 has the lowest conversion efficiency, which is reduced by 0.15% compared with the solar cell obtained in the example 1, because the physical isolation of the P/N region is not arranged on the back surface, and the BSG layer is not reserved for phosphorus expansion;
From the analysis comparison, the invention can form a concave-convex alternate arrangement structure on the back of the battery through grooving, so that P, N areas respectively formed in the concave-convex structure are physically isolated, meanwhile, phosphorus diffusion can be effectively promoted to form a back N area and a heavy doping area through the reserved thinned BSG layer, meanwhile, the reserved thinned BSG layer can play a passivation effect, and when the technical effects are jointly exerted in the battery, uoc, isc and FF of the obtained solar battery are further improved and enhanced, and finally, the conversion efficiency of the solar battery is effectively improved.
The detailed structural features of the present invention are described in the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must be implemented depending on the above detailed structural features. It should be apparent to those skilled in the art that any modifications of the present invention, equivalent substitutions of selected components of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope of the present invention and the scope of the disclosure.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.
In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.
Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.
Claims (38)
1. The manufacturing method of the interdigital back contact solar cell is characterized by comprising the following steps of:
(1) Preparing a silicon substrate and performing double-sided polishing;
(2) Windowing is carried out on the back surface of the polished silicon substrate to form a first groove and a non-windowed convex surface area, so that a staggered structure with alternately arranged concave and convex surfaces is formed on the back surface of the silicon substrate; the depth of the first groove is 5-20 mu m, and the width of the first groove is 60-900 mu m; the width of the non-windowed convex surface area is 600-1500 mu m;
(3) Performing texturing on the front surface of the polished silicon substrate to form a texturing structure;
(4) Boron expansion is carried out on the texturing structure and the staggered structure to form a front BSG layer and a back BSG layer respectively;
(5) Modifying and thinning the front BSG layer and the back BSG layer to form a front thinned BSG layer and a back thinned BSG layer; the thickness of the front side thinned BSG layer and the back side thinned BSG layer is 10-40 nm;
(6) Preparing passivation films on the front side thinned BSG layer and the back side thinned BSG layer to obtain a front side passivation layer and a back side passivation layer;
(7) Re-windowing the corresponding position of the first groove or the non-windowed convex surface region on the back passivation layer to form a second groove, wherein the width of the second groove is 20-50 mu m, and the back thinning BSG layer is exposed; performing phosphorus expansion through the back thinning BSG layer in the second groove; the phosphorus-expanded reaction gas is POCl 3 And O 2 The method comprises the steps of carrying out a first treatment on the surface of the The POCl 3 And O 2 The flow ratio of (1-2) is 1; the POCl 3 The flow rate of the water is 500-2000 sccm; the phosphorus expansion is carried out under 50-150 Pa; the temperature of the phosphorus expansion is 770-830 ℃ and the time is 150-250 s; the doping concentration of the phosphorus diffusion is 10 19 ～10 21 cm -3 ；
(8) Forming a negative electrode in the second groove through screen printing, so that ohmic contact is generated between the negative electrode and the doped region formed by phosphorus expansion; manufacturing a positive electrode, and enabling the positive electrode to penetrate through the back passivation layer to generate ohmic contact with the doped region formed by boron expansion, so as to obtain an interdigital back contact solar cell;
Wherein, the step (2) and the step (3) are not in sequence.
2. The method of claim 1, wherein the double-sided polishing in step (1) comprises rough polishing, cleaning, and then alkali polishing.
3. The method of claim 1, wherein the silicon substrate of step (1) comprises an N-type and/or P-type silicon wafer.
4. The method according to claim 2, wherein the aqueous solution for rough polishing comprises NaOH and/or KOH.
5. The method according to claim 4, wherein the volume ratio of NaOH and/or KOH to water in the coarse polishing aqueous solution is (2-10) (300-380).
6. The method according to claim 2, wherein the rough polishing temperature is 69-79 ℃ and the time is 100-180 s.
7. The method according to claim 2, wherein the aqueous alkali polishing solution used for alkali polishing comprises NaOH and/or KOH and an alkali polishing additive.
8. The manufacturing method according to claim 7, wherein the volume ratio of NaOH and/or KOH, alkali polishing additive and water in the alkali polishing aqueous solution is (6-10): 4-6): 335-340.
9. The method according to claim 2, wherein the alkaline polishing temperature is 65-80 ℃ and the alkaline polishing time is 200-300 s.
10. The method of claim 1, wherein the windowing methods of step (2) and step (7) comprise laser windowing and/or mask etching.
11. A method according to claim 1, wherein the aqueous texturing solution used in the texturing of step (3) comprises NaOH and/or KOH and a texturing additive.
12. The method according to claim 11, wherein the volume ratio of NaOH and/or KOH, the texturing additive and water in the aqueous texturing solution is (3-13): 0.3-4.3): 326-346.
13. The method according to claim 1, wherein the temperature of the texturing in the step (3) is 370-470 ℃ and the time is 60-100 s.
14. The method of claim 1, wherein the boron diffusion of step (4) comprises pre-deposition followed by diffusion by push-in.
15. The method of claim 14, wherein the pre-deposition temperature is 850-950 ℃ for 18-50 min.
16. The method of claim 14, wherein the pre-deposited boron source comprises B (CH 3 O) 3 、C 9 H 21 BO 3 、BCl 3 Or BBr 3 Any one or a combination of at least two of these.
17. The method of claim 14, wherein the pre-deposited oxygen has a flow rate of 100-3000 sccm.
18. The method of claim 14, wherein the pre-deposited source-carrying nitrogen has a flow rate of 200-1200 sccm.
19. The method of claim 14, wherein the pre-deposited main nitrogen has a flow rate of 2000-20000 sccm.
20. The method of claim 14, wherein the diffusion temperature is 950-1100 ℃ for 30-50 min.
21. The method according to claim 1, wherein the boron diffusion in step (4) has a doping concentration of 10 19 ～10 21 cm -3 。
22. The method of claim 1, wherein the front BSG layer and the back BSG layer in step (4) each have a thickness of 30 to 90nm.
23. The method according to claim 1, wherein the etching cleaning liquid for the modification and thinning in the step (5) comprises an HF solution with a mass fraction of 20-40 wt%.
24. The method according to claim 1, wherein the time for the modification and thinning in the step (5) is 50 to 250 seconds.
25. The method of claim 1, wherein the front passivation layer and the back passivation layer in step (6) are both comprised of SiN x 。
26. The method of claim 1, wherein the method of preparing a passivation film in step (6) comprises a PECVD method.
27. The method of claim 26, wherein the plasma rf power of the PECVD process is 9000-20000W.
28. The method of claim 26, wherein the temperature of the PECVD process is 450-500 ℃.
29. The method of claim 26, wherein the reaction gas of the PECVD process is SiH 4 And NH 3 。
30. The method of claim 29, wherein the SiH is 4 And NH 3 The flow ratio of (2) is 1 (4-10).
31. The method of claim 30 wherein the SiH is 4 The flow rate of the catalyst is 500-2300 sccm.
32. The method according to claim 26, wherein the PECVD process is performed at 220 to 240 Pa.
33. The method of claim 1, wherein the front passivation layer and the back passivation layer in step (6) are both 70-90 nm thick.
34. The method of claim 1, wherein the refractive indices of the front passivation layer and the back passivation layer in step (6) are each 1.98-2.03.
35. The method of claim 1, wherein the material of the negative electrode in step (9) comprises silver.
36. The method of claim 1, wherein the positive electrode in step (9) is made of aluminum.
37. The method of manufacturing according to claim 1, characterized in that the method comprises the steps of:
(1) Preparing an N-type and/or P-type silicon wafer as a silicon substrate and performing double-sided polishing, firstly performing rough polishing for 100-180 s at 69-79 ℃ by using a rough polishing aqueous solution, cleaning by using water, and then performing alkali polishing for 200-300 s at 65-80 ℃ by using an alkali polishing aqueous solution; the volume ratio of NaOH and/or KOH to water in the coarse polishing aqueous solution is (2-10) (300-380); the volume ratio of NaOH and/or KOH and alkali polishing additive to water in the alkali polishing aqueous solution is (6-10): 4-6): 335-340;
(2) Using a laser windowing and/or mask etching method to window the back surface of the polished silicon substrate to form a first groove with the depth of 5-20 mu m and the width of 60-900 mu m and a non-windowed convex surface area with the width of 600-1500 mu m, so that the back surface of the silicon substrate forms a staggered structure with concave-convex alternately arranged;
(3) Using a texturing water solution to perform texturing on the front surface of the silicon substrate at 370-470 ℃ for 60-100 s to form a texturing structure; the volume ratio of NaOH and/or KOH and the wool making additive to water in the wool making aqueous solution is (3-13) (0.3-4.3) (326-346);
(4) The doping concentration of the wool making structure and the staggered structure is 10 19 ～10 21 cm -3 Forming a front BSG layer and a back BSG layer with the thickness of 30-90 nm respectively; the boron diffusion comprises the steps of pre-depositing for 18-50 min at 850-950 ℃ and then performing pushing diffusion for 30-50 min at 950-1100 ℃; the pre-deposited boron source comprises B (CH 3 O) 3 、C 9 H 21 BO 3 、BCl 3 Or BBr 3 Any one or a combination of at least two of the following; the flow rate of the pre-deposited oxygen is 100-3000 sccm; the flow of the pre-deposited source carrying nitrogen is 200-1200 sccm; the flow rate of the pre-deposited main nitrogen is 2000-20000 sccm;
(5) Modifying and thinning the front BSG layer and the back BSG layer in an HF solution with the mass fraction of 20-40 wt% for 50-250 s to form a front thinned BSG layer and a back thinned BSG layer with the thickness of 10-40 nm;
(6) SiN is carried out on the front surface thinning BSG layer and the back surface thinning BSG layer by adopting a PECVD method x Coating to obtain a front passivation layer and a back passivation layer with the thickness of 70-90 nm and the refractive index of 1.98-2.03; the plasma radio frequency power of the PECVD method is 9000-20000W, the temperature is 450-500 ℃, and the reaction gas is SiH 4 And NH 3 And SiH 4 And NH 3 The flow ratio of (2) is 1 (4-10), wherein SiH 4 The flow rate of the catalyst is 500-2300 sccm, and the PECVD method is carried out under 220-240 Pa;
(7) Re-windowing the corresponding position of the first groove or the non-windowed convex surface region on the back passivation layer to form a second groove with the width of 20-50 mu m, and exposing the back thinning BSG layer; then carrying out phosphorus expansion for 150-250 s at 770-830 ℃ through the back thinning BSG layer in the second groove, so that the doping concentration of phosphorus is 10 19 ～10 21 cm -3 The method comprises the steps of carrying out a first treatment on the surface of the The phosphorus-expanded reaction gas is POCl 3 And O 2 And POCl 3 And O 2 The flow ratio of (1-2): 1, wherein the POCl 3 The flow rate of the water is 500-2000 sccm; the phosphorus expansion is carried out under 50-150 Pa;
(8) Forming a silver electrode in the second groove as a negative electrode through screen printing, so that ohmic contact is generated between the negative electrode and the doped region formed by phosphorus expansion; an aluminum electrode is manufactured as a positive electrode, and the positive electrode passes through the back passivation layer and generates ohmic contact with the doped region formed by boron expansion, so that an interdigital back contact solar cell is obtained;
Wherein, the step (2) and the step (3) are not in sequence.
38. An interdigital back contact solar cell obtained by the method of any one of claims 1-37.
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Denomination of invention: A manufacturing method for interdigital back contact solar cells and the produced interdigital back contact solar cells Effective date of registration: 20231102 Granted publication date: 20230728 Pledgee: Dongyang Branch of China Construction Bank Co.,Ltd. Pledgor: HENGDIAN GROUP DMEGC MAGNETICS Co.,Ltd. Registration number: Y2023980063485 |