59 results about "Phosphorus diffusion" patented technology

The invention relates to a preparation process of a TBC battery. The TBC battery comprises a substrate; the substrate is polished and cleaned; the doping treatment process comprises a first doping process and a second doping process, the first doping process is used for carrying out boron diffusion, and the second doping process is used for carrying out phosphorus diffusion; performing a high-temperature annealing process of high-temperature junction pushing on the substrate treated by the doping treatment process; carrying out PSG removal and front surface and side surface alkali polishing processes on the substrate treated by the high-temperature annealing process; and depositing an aluminum oxide layer, a silicon nitride layer and an electrode on the substrate. Boron expansion and phosphorus expansion are respectively carried out on the substrate, and junction pushing is not carried out; boron diffusion and phosphorus diffusion knot pushing processes are carried out in the same high-temperature environment, so that the thermal history is shortened, the energy consumption is reduced, the process flow is simplified, the production cost is reduced, and the production efficiency is improved.

The invention provides a TBC battery, a preparation method thereof and a photovoltaic module, and relates to the technical field of solar cells, and the front surface structure of the TBC battery comprises an N + front surface field layer, a front phosphorosilicate glass layer, a passive film layer and an antireflection film layer which are sequentially stacked on the front surface of a silicon substrate; wherein the N + front surface field layer is a high-concentration N-type region formed by doping phosphorus atoms on the front surface through phosphorus diffusion. An N + front surface field (FSF) is added on the front surface of the cell, phosphorus atoms are doped on the front surface through phosphorus diffusion to form an N + region, an N-N + high-low junction is formed with an N-type silicon substrate, minority carriers are repelled, and the field passivation effect is improved.

The invention relates to the photovoltaic field, and discloses a hot spot prevention structure of a back contact battery and a preparation method of the hot spot prevention structure. According to the hot spot prevention structure of the back contact battery, the boron-doped layer and the extended phosphorus-doped layer are disconnected through the gap; wherein the boron diffusion layer and the phosphorus diffusion layer can form a conductive channel, the conductive channel is located in the semi-silicon substrate and is formed by diffusing boron / phosphorus atoms into the silicon substrate and diffusing the boron / phosphorus atoms to the periphery, and the design can avoid generation of larger conduction electric leakage. According to the hot spot prevention structure of the back contact battery, the electric leakage loss can be effectively reduced on the basis of reducing the risk of generating a hot spot effect at the assembly end.

The invention discloses a passivation contact cell with a selective Poly structure, a preparation method of the passivation contact cell and a photovoltaic module. The passivation contact cell comprises an N-type silicon wafer substrate, a metal contact area and a non-metal contact area, wherein the metal contact area is sequentially provided with a phosphorus diffusion layer, a tunneling oxide layer, a phosphorus-doped polycrystalline silicon layer and a back surface passivation anti-reflection film from inside to outside; the non-metal contact region comprises a third region with phosphorus diffusion and a fourth region with a recess on the silicon substrate, the third region is sequentially provided with a phosphorus diffusion layer and a back surface passivation anti-reflection film from inside to outside, and the fourth region is provided with a back surface passivation anti-reflection film on the surface of the recess structure. According to the passivation contact battery, the transverse transmission of back current can be improved, the filling factor of the battery is improved, and the Voc of the battery can be prevented from being greatly reduced. And the optical performance of the cell can be remarkably improved, and the long-wave quantum efficiency is improved, so that the current and double-sided rate of the cell are improved.

The invention discloses a phosphorus diffusion method for improving photoelectric conversion efficiency of a BC type battery, which realizes high sheet resistance (20-150 omega) with excellent uniformity while obtaining high impurity concentration PSG by improving a phosphorus diffusion process after an N-type BC type battery LP route N-poly, thereby improving FF of the BC type battery, reducing contact resistance Rs and finally improving the photoelectric conversion efficiency of the battery to a greater extent. And secondly, a multi-step source-passing method is adopted, the source-passing time is shortened, the source-passing flow is increased, rapid temperature rise propulsion and the like are adopted, a conventional phosphorus diffusion method is changed, high sheet resistance with excellent uniformity is realized while high-impurity-concentration PSG is obtained, reduction of N-region carrier recombination is ensured, FF and Uoc are improved, and finally the conversion efficiency of the battery is improved to the maximum extent.

The invention provides a TBC battery and a preparation method thereof. The current density is remarkably improved by adjusting printing and laser patterns, reducing the area of a P region or / and an N region, increasing the area of a gap region, reducing the metal shielding area and improving the photon utilization rate; and compounding of a metal region is reduced, and Voc and passivation performance of the battery piece are improved. By polishing the gap region with the pyramid suede, the reflection of incident light in the silicon substrate can be increased, so that the Isc of the cell is improved, and meanwhile, as the initial gap region is protected by the mask layer and is not damaged by wet corrosion subsequently, the height difference between the gap region and the boron / phosphorus diffusion layer can be reduced, the transverse transmission of carriers in the silicon substrate is facilitated, and the FF is improved. According to the TBC battery prepared by the method, under the condition that the number of partitions on the back surface of the battery is not changed, the areas of the P region and the N region are reduced, so that the area of the gap region is increased, the metal shielding area is reduced, the photon utilization rate is improved, and the current density is obviously improved; and compounding of a metal region is reduced, and Voc and passivation performance of the battery piece are improved.

The present invention relates to the field of solar cells. Disclosed are a lateral-vertical composite multi-junction TBC solar cell and a manufacturing method therefor. The TBC solar cell comprises an N-type silicon wafer. The front surface of the N-type silicon wafer is sequentially provided with a pyramid textured surface and a passivation layer; the back surface of the N-type silicon wafer is provided with a deposition region A and a deposition region B distributed in an interdigitated manner; a gap between the deposition region A and the deposition region B serves as an isolation region, and the surface of the isolation region is sequentially provided with the pyramid textured surface and the passivation layer; the surface of the deposition region A is sequentially provided with a boron diffusion layer A, a phosphorus diffusion layer A, a tunneling oxide layer A, a phosphorus diffusion layer B, the passivation layer and an electrode layer; the surface layer of the N-type silicon wafer located at the bottom of the deposition region B is a boron diffusion layer B, and the surface of the deposition region B is sequentially provided with a tunneling oxide layer B, a boron diffusion layer C, the passivation layer and the electrode layer. The TBC solar cell of the present invention has a lateral-vertical composite multi-junction structure, which is beneficial to further improving the cell conversion efficiency of the cell and also reducing the manufacturing cost and technical difficulty of the cell.

The application relates to the field of solar cell manufacturing, and particularly discloses a TOPCon cell and a preparation method thereof. A front surface oxidation layer is obtained by front surface oxidation of a silicon substrate; a back surface oxidation layer and a polysilicon layer are sequentially arranged on the back surface of the silicon substrate; a SE area of the front surface oxidation layer is laser grooved to obtain a diffusion precursor, grooves on the front surface of the diffusion precursor penetrate the front surface oxidation layer; boron diffusion is performed on the front surface of the diffusion precursor to obtain a cell precursor; after back surface phosphorus diffusion, surface passivation and electrode arrangement are performed on the cell precursor, the TOPCon cell is obtained. The TOPCon cell is produced by only one diffusion, so that the process flow is simplified, the service life of a reaction furnace is greatly prolonged, the demand for boron diffusion reagents in the production process is reduced, and the production cost is greatly reduced.

The application discloses a Topcon battery and a preparation method thereof, a solar module and a solar system, and relates to the technical field of solar cells. The preparation method of the Topcon battery comprises the following steps: step 1, providing a substrate, and performing a texturing treatment on the surface of the substrate; step 2, obtaining a P+ layer through boron doping and BSG removal; step 3, obtaining a tunneling oxide layer and a doped polysilicon layer by adopting LPCVD and high-temperature phosphorus diffusion; step 4, obtaining an aluminum oxide layer on the front surface of the substrate by adopting ALD; step 5, obtaining a front surface silicon nitride layer on the front surface of the substrate by adopting PECVD; step 6, obtaining a back surface silicon nitride layer on the back surface of the substrate by adopting PECVD, and modifying the doped polysilicon layer, so that a polysilicon layer doped with carbon elements is formed on the surface of the doped polysilicon layer. The application does not need to increase additional equipment, is compatible with the existing LPCVD equipment for preparing the Topcon battery containing the polysilicon layer doped with carbon elements, is simple to operate, low in cost and suitable for large-scale popularization.

Provided are N-type monocrystalline silicon double-sided solar cell and preparation method thereof. Preparation method includes following steps: S1: performing double-sided texturing to obtain N-type monocrystalline silicon with front surface and back surface having first textured structures respectively; S2: performing back-surface phosphorus diffusion doping to form back surface field; S3: removing winding plating and PSG on front surface and back surface, forming mask for protecting first textured structure of back surface on surface of back surface field, and manufacturing second textured structure on front surface of N-type monocrystalline silicon; S4: performing front-surface boron diffusion doping to form front-surface doped emitter junction layer; S5: after removal of mask, winding plating and BSG on front surface and back surface, depositing passivation antireflection layer on surface of front-surface doped emitter junction layer, and depositing passivation layer on surface of back surface field; and S6: preparing front surface electrode and back surface electrode.

The application discloses a preparation method of a TBC solar cell, which comprises the following steps: dipping a substrate into a specified solution at a predetermined temperature to perform texturing, and controlling the texturing time within a predetermined time; sequentially depositing a tunneling oxide layer and an intrinsic polysilicon layer on the back of the substrate; depositing a mask layer on the side of the intrinsic polysilicon layer away from the tunneling oxide layer; forming a first opening area on the mask layer, and performing boron diffusion on the first opening area to form a boron-doped polysilicon layer; forming a second opening area on the mask layer, and performing phosphorus diffusion on the second opening area to form a phosphorus-doped polysilicon layer; the mask layer remains between the first opening area and the second opening area; and depositing an anti-reflection layer on the back of the substrate. The application can shorten the production process and reduce the risk of laser damage to the cell.

A solar cell and its fabrication method are disclosed. The fabrication method includes the following steps: depositing a tunneling layer and an amorphous silicon layer on the back side of a P-type silicon substrate, wherein the back side of the silicon substrate has a first region and a second region; fabricating a barrier layer of a first thickness in the electrode region of the first region and a barrier layer of a second thickness in the non-electrode region of the first region; diffusion doping the amorphous silicon layer using an N-type doping source to form an N-type doped crystalline silicon layer and an oxide layer; removing the oxide layer and the N-type doped crystalline silicon layer in the second region; fabricating a first electrode in the electrode region of the first region and a second electrode in the electrode region of the second region. The fabrication method of this invention forms barrier layers of different thicknesses in the first region, which have different blocking effects on phosphorus diffusion. During phosphorus diffusion, a selective emitter is formed in the first region, improving cell efficiency. Furthermore, the barrier layers are corrosion-resistant to alkaline solutions, protecting the N-poly layer in the first region during subsequent processes while completely removing the N-poly layer in the second region, thus improving cell yield.

The invention provides a local junction cell structure and a preparation process thereof. The preparation process comprises the following steps: S1, texturing; s2, boron diffusion; s3, alkali polishing; s4, back surface growth; s5, phosphorus diffusion; s6, opening the film; s7, structuring is carried out; and S8, post-processing to form the photovoltaic cell with the local junction structure. According to the local junction cell structure, the limitation of transmission resistance in the prior art can be broken, the open-circuit voltage is improved, the transmission resistance is reduced, and the efficiency is improved.

The application relates to the field of topcon cells, in particular to a novel structure topcon cell and a preparation method thereof, which comprises the following steps: (1) front texturing: performing texturing on the front surface of an n-type silicon substrate, and then performing boron diffusion to obtain an n-type silicon substrate containing a boron diffusion layer; (2) front passivation and anti-reflection: depositing a passivation layer on the front surface of the n-type silicon substrate containing the boron diffusion layer, and then depositing an anti-reflection layer on the passivation layer; (3) back through-passivation layer: depositing an ultrathin through-oxidation layer on the back surface of the n-type silicon substrate, then growing a polysilicon layer on the ultrathin through-oxidation layer, and performing phosphorus diffusion to form a phosphorus-doped polysilicon layer; and (4) printing electrodes. In the application, a plurality of groups of aluminum grid lines are used to replace a traditional full-aluminum back field on the back electrode, interval silver electrodes are adopted, and interconnection materials are used for connection, so that the prepared cell has little difference in performance from a traditional topcon cell, the consumption of aluminum and silver is reduced, and the production cost is reduced.

The invention discloses a preparation method of a TBC solar cell. The preparation method comprises the following steps: alkali polishing; sequentially depositing a silicon dioxide tunneling oxide layer and an intrinsic amorphous silicon layer; carrying out boron diffusion conversion to obtain P-type polycrystalline silicon; laser patterning is prepared for N region deposition; acid pickling and alkali polishing; sequentially depositing a silicon dioxide tunneling oxide layer and an intrinsic amorphous silicon layer again; carrying out phosphorus diffusion conversion to obtain N-type polycrystalline silicon; removing PSG from the front side; patterning to expose the N-type polycrystalline silicon region; performing alkali texturing treatment to form a pyramid structure, and performing rounding treatment; pickling the back surface and reserving the polycrystalline silicon layer; depositing an aluminum oxide passivation layer and a silicon nitride passivation layer on two sides; laser trepanning is carried out to expose the P-type polycrystalline silicon region and the N-type polycrystalline silicon region; metallizing to form a precise electrode; and performing light injection to obtain the TBC solar cell. According to the TBC solar cell provided by the invention, BSGamp; the PSG is used as a mask, and the laser patterning / corrosion slurry is used for replacing photoetching and other mask materials, so that the compatibility with the existing TOPCON production line is high.

The invention provides a preparation method of a back contact cell capable of eliminating the height difference of a P / N region. The preparation method comprises the following steps: providing a silicon substrate; carrying out alkali polishing treatment on the silicon substrate, and carrying out phosphorus diffusion on the front surface and the back surface to form a phosphorus diffusion layer; defining two adjacent regions on the back surface as a first region and a second region, removing the phosphorus diffusion layer in the first region, and etching the silicon substrate downwards to form a first groove; sequentially depositing a tunneling oxide layer and an amorphous silicon layer on the whole back surface of the silicon substrate, and performing boron diffusion to form a first doped polycrystalline silicon layer; the first doped polycrystalline silicon layer in the second area is removed, the silicon substrate is etched downwards, a second groove is formed, and the bottom of the second groove is flush with the bottom of the first groove; forming a second doped polycrystalline silicon layer on the back surface of the silicon substrate; and removing the second doped polycrystalline silicon layer in the first region, and synchronously removing the second doped polycrystalline silicon layer at the junction of the second region and the first region to form a groove for isolating the first doped polycrystalline silicon layer from the second doped polycrystalline silicon layer.

The present disclosure provides a solar cell, a preparation method thereof and a photovoltaic module, and relates to the technical field of photovoltaics. By setting the P region as a three-dimensional structure with a groove-shaped curved surface, the effective surface area of the P region is increased (rather than simply the geometric projected area) without changing the geometric area of the N region and affecting the depth requirement of the N-type doped phosphorus diffusion layer, thereby significantly improving the emitter current collection efficiency of the solar cell. In addition, the groove-shaped curved surface structure not only increases the effective collection area, but also optimizes the carrier transport path, reduces the lateral transport resistance, and the curved surface structure helps to improve the passivation layer coverage quality, thereby synergistically improving the open-circuit voltage (Voc) and the fill factor (FF), and ultimately improving the photoelectric conversion efficiency of the cell.

The invention relates to the technical field of photovoltaics, in particular to a phosphorus diffusion method and a phosphorus diffusion furnace, and aims to reduce the amount of solids left in a filter in a phosphorus diffusion process and prolong the service life of a filter element of the filter. The phosphorus diffusion method comprises the steps that after a furnace door of a furnace body is opened, tail gas in the furnace body is extracted, so that air enters the furnace body, the air and the tail gas sequentially flow through a cooler and a filter, and the cooler comprises a container and cooling liquid arranged in the container; and when extraction of the tail gas in the furnace body reaches a first preset duration, extraction of the tail gas in the furnace body is stopped. After a furnace door of a furnace body is opened, tail gas in the phosphorus diffusion furnace is extracted, air enters the furnace body, oxygen and water in the air can react with the tail gas in the furnace body to generate water-soluble substances such as phosphoric acid, more substances in the tail gas are left in a cooler, and then the substances entering a filter can be reduced; the amount of solid left in the filter is reduced, and the service life of a filter element of the filter is prolonged.

The invention relates to a perovskite crystalline silicon laminated cell, a bottom cell and a preparation method, and the method comprises the steps: obtaining a textured semiconductor substrate layer, and carrying out the boron diffusion of a first surface of the semiconductor substrate layer, and generating a boron-doped layer; carrying out winding plating removal and polishing on the second surface of the semiconductor substrate layer, carrying out secondary texturing to form a textured surface, carrying out deposition in sequence to generate a tunneling oxide layer and an intrinsic polycrystalline silicon layer, and carrying out phosphorus diffusion on the intrinsic polycrystalline silicon layer to obtain an N-type polycrystalline silicon layer; depositing a passivation film layer on the boron-doped layer, carrying out passivation treatment, printing silver paste on the passivation film layer, and carrying out sintering to generate a metal electrode; the transparent conductive layer is generated on the N-type polycrystalline silicon layer, and annealing is carried out after auxiliary sintering is carried out by adopting an LECO technology, so that the open voltage of the bottom cell can be improved, and the conversion efficiency of the cell is improved.

The invention relates to a TOPCon battery preparation method for improving UVID and a TOPCon battery, and the method comprises the steps: depositing a first tunneling oxide layer and a barrier polycrystalline silicon layer on the back surface of a processed silicon substrate, and depositing a second tunneling oxide layer and a doped polycrystalline silicon layer on the deposited barrier polycrystalline silicon layer again; forming a silicon dioxide masking film on the back surface of the silicon substrate, and performing back surface phosphorus diffusion; carrying out atomic layer deposition on the front surface of the silicon substrate to form an aluminum oxide layer and carrying out passivation treatment; pECVD deposition is carried out on the front surface and the back surface of the silicon substrate to form a thin film, and passivation treatment is carried out; a main grid and an auxiliary grid line are respectively screen-printed on the front surface and the back surface of the silicon substrate. The thin film on the front side comprises seven layers of structures which are sequentially stacked, the refractive index of the silicon nitride layer is optimized, generation of Si-H covalent bonds is adjusted, and the light absorption capacity is reduced, so that the UVID is greatly improved, and the UVID amplitude of the TOPCon battery is reduced.

This invention discloses a method for controlling the curvature of a diffuser sheet through an oxide layer, belonging to the field of power semiconductor device technology. The oxide layer is a silicon dioxide layer, and the diffuser sheet is a semiconductor silicon diffuser sheet that has been processed by a diffusion process and then bent towards the non-diffusion surface. The method includes: obtaining the stress parameters of the diffuser sheet; determining the target stress value that the silicon dioxide layer needs to provide based on the stress parameters; calculating the target thickness of the silicon dioxide layer based on the target stress value, the material parameters of the diffuser sheet and the silicon dioxide layer; and growing a silicon dioxide layer with the target thickness on the diffusion surface side, so that the stress generated by this layer cancels out the stress generated by the diffusion process in the diffuser sheet, thereby controlling the curvature. This invention accurately calculates the required oxide layer thickness using a theoretical model, utilizes the stress provided by the thermally oxidized silicon dioxide layer to counteract the stress introduced by phosphorus diffusion, precisely controls the curvature without damaging the non-diffusion polished surface, and is compatible with existing processes.

The application provides a solar cell preparation device and a solar cell preparation method. The solar cell preparation device comprises a reaction module and a gas module. The reaction module has a reaction cavity for accommodating a reaction part. The gas module is used for respectively conveying a first gas and a second gas to the reaction cavity. The first gas comprises a vapor deposition reaction gas and a first purge gas. The second gas comprises a phosphorus diffusion reaction gas and a second purge gas. The reaction module with one reaction cavity is provided, and the gas module capable of respectively controlling the first gas and the second gas is matched. Two independent chemical vapor deposition processes and phosphorus diffusion processes can be integrated into one reaction cavity, one heating cycle is completed, the space occupied by the device is reduced, the energy consumption is reduced, the preparation efficiency is improved, the production cost is reduced, the risk of product damage caused by pollution in the preparation process is reduced, cross contamination and pre-reaction are avoided, and the product performance is improved.

The present disclosure provides a solar cell and a preparation method thereof, and belongs to the technical field of solar cells. The back surface of the solar cell has a passivation contact structure only at the position corresponding to the non-metallic region. The passivation contact structure forms an etching step with an inclination angle of 40-60 degrees at the position where the metallic region and the non-metallic region meet. The etching step with the above inclination angle can make the transition between the non-metallic region and the metallic region smoother than the vertical etching step, and is more conducive to the uniformity of the subsequent passivation film layer and the transportation of back surface carriers, thereby improving the passivation level of the solar cell. The preparation of the solar cell comprises: double-sided texturing, boron diffusion and oxidation, BSG removal and alkali etching, LPCVD and phosphorus diffusion, and back surface patterning of the N-type silicon substrate; removing the PSG on the front surface of the N-type silicon substrate, using an alkali solution and a specific anti-plating additive for RCA cleaning, and removing the tunneling oxide layer and the doped polysilicon layer on the back surface of the N-type silicon substrate corresponding to the metallic region.

The invention discloses a TBC battery preparation method based on quartz mask isolation diffusion. The TBC battery preparation method comprises the following steps: S1, providing a silicon wafer provided with a tower base and a poly layer; s2, providing a quartz isolation device, wherein the quartz isolation device is provided with a diffusion structure for forming an interdigital PN junction on the surface of the silicon wafer through diffusion; the diffusion structure is an interdigital structure formed by mutually crossing but not communicating a boron diffusion quartz pipeline and a phosphorus diffusion quartz pipeline, and the boron diffusion quartz pipeline and the phosphorus diffusion quartz pipeline are respectively provided with an air inlet and an air outlet; s3, pushing the diffusion device provided with the quartz isolation device and the silicon wafer into a diffusion furnace tube, and performing boron source diffusion and phosphorus source diffusion in the same diffusion furnace tube by using the quartz isolation device so as to form an interdigital PN junction on the surface of the silicon wafer at one time; and S4, carrying out a subsequent C cell preparation process which comprises the steps of removing a winding and expanding oxide layer in a GAP region in the middle of a PN junction by laser, carrying out texturing, depositing a passive film and an antireflection film, and metallizing a printed electrode to complete the preparation of the TBC cell.

The invention relates to an efficient gettering method for a heterojunction solar cell and a silicon wafer, and belongs to the technical field of silicon wafer manufacturing, and the method comprises the following steps: S1, adding a carbon dopant into a polycrystalline silicon raw material, and growing a high-carbon-concentration monocrystalline silicon rod by using a czochralski method; s2, cutting the monocrystalline silicon rod in the step S1 to obtain a silicon wafer; and S3, carrying out phosphorus diffusion gettering treatment on the silicon wafer in the step S2 at the set temperature and time. According to the gettering method, the size of the original oxygen precipitate of the grown silicon wafer is reduced, the inner gettering capacity of the oxygen precipitate is weakened, metal impurities in the silicon wafer are more effectively removed through outer gettering, the minority carrier lifetime of the silicon wafer is prolonged, and therefore the battery efficiency is improved.

The invention relates to a preparation method of a back contact battery, the battery and an assembly, and belongs to the technical field of photovoltaic power generation. Comprising; preparing a monocrystalline silicon substrate; forming a P + doping layer and a BSG oxidation film on the back surface of the monocrystalline silicon substrate through boron diffusion; photoresist is printed on a P area on the back face of the silicon wafer and cured, and a Mask1 mask layer is formed; sequentially removing the BSG oxidation film and the Mask1 mask layer; sequentially generating a tunneling oxide layer and an intrinsic Poly layer on the back surface; phosphorus diffusion: converting the intrinsic Poly layer in the phosphorus diffusion design area into an N-Poly layer, and forming a PSG layer at the outer side; photoresist is printed on the N area of the back face of the silicon wafer and cured, and a mask2 mask layer is formed; corroding the PSG oxide layer, performing alkali texturing by using a solution, simultaneously removing the mask 2 mask layer, performing surface cleaning after texturing, and removing the BPSG mask layer by using a solution; performing double-sided aluminum oxide thin plating; carrying out double-sided antireflection film deposition; and preparing the electrode. On the basis of production line TOPCon equipment, only photoetching equipment needs to be additionally arranged, and the equipment transformation cost is far lower than that of an existing N-TBC.

The application relates to the technical field of solar cells, in particular to a solar cell preparation method, a solar cell, a laminated cell and a photovoltaic module. The preparation method comprises the following steps: preparing a tunneling oxide layer on a first surface of a substrate; depositing polycrystalline silicon on the surface of the tunneling oxide layer along the thickness direction under a first deposition condition, and gradually reducing the first deposition condition to a second deposition condition; and performing phosphorus diffusion doping on the polycrystalline silicon layer under a first doping condition, and converting the polycrystalline silicon layer into a doped polycrystalline silicon layer. The application gradually reduces the deposition condition to form a polycrystalline silicon layer with gradually changed crystallization rate, thereby forming a doped polycrystalline silicon layer with gradually changed doping concentration during phosphorus diffusion, making the side of the doped polycrystalline silicon layer close to the substrate have low doping concentration, effectively blocking the diffusion of phosphorus atoms, reducing the risk of phosphorus atom diffusion through the substrate, and improving the passivation level. Meanwhile, the side of the doped polycrystalline silicon layer away from the substrate has high doping concentration, which is beneficial to metal contact and improves the conversion efficiency.

The invention discloses a TOPCon solar cell and a preparation method thereof, and belongs to the field of solar cells, a laminated structure of a tunneling oxide layer / a first amorphous silicon layer / a first PSG layer / a second amorphous silicon layer / a second PSG layer is formed on the back surface of a silicon wafer, and a first phosphorus-doped polycrystalline silicon layer and a second phosphorus-doped polycrystalline silicon layer are formed after phosphorus diffusion; wherein the phosphorus doping concentration of the first phosphorus-doped polycrystalline silicon layer is lower than that of the second phosphorus-doped polycrystalline silicon layer. The distribution of phosphorus atoms in the doped polycrystalline silicon layer is controlled, so that the phosphorus doping concentration, close to the silicon substrate, of the metal electrode contact area is low, and the passivation performance between the silicon substrate and the tunneling oxide layer is improved in cooperation with the tunneling oxide layer; the doping concentration of phosphorus close to the metal electrode is high, and the contact performance is improved, so that phosphorus atoms entering the silicon substrate are reduced, and the temperature window of phosphorus diffusion is increased.

The invention discloses a phosphorus diffusion annealing method and a preparation method of a TBC battery, and the phosphorus diffusion annealing method comprises the following steps: A1, carrying out the high-temperature heating of a silicon wafer in a quartz furnace tube, carrying out the pressure pumping, first-time heating and leakage detection, carrying out the second-time heating and boosting, introducing nitrogen, carrying out the annealing crystallization, and crystallizing a boron-doped microcrystalline silicon layer into a P-type polycrystalline silicon layer; a2, cooling, and introducing oxygen and nitrogen for pre-oxidation; a3, phosphorus oxychloride, oxygen and nitrogen are introduced for deposition to form a phosphorus-rich layer, then pressure returning is carried out, nitrogen is introduced, temperature rising is carried out, an N-type polycrystalline silicon poly layer is formed, winding and expanding layers are formed on the front face and the edge at the same time, nitrogen is introduced for purging, pressure returning is carried out, nitrogen is introduced, and temperature rising is carried out; and A4, cooling and boosting, introducing oxygen to form a PSG layer, cooling, introducing nitrogen, and returning pressure out of the quartz furnace tube. According to the invention, a boron diffusion process with high investment and high operation cost can be canceled in a TBC battery preparation process, and the investment cost of 1500-20 million yuan / GW can be reduced.