CN115881849A - Preparation method of TOPCon battery local passivation contact structure - Google Patents
Preparation method of TOPCon battery local passivation contact structure Download PDFInfo
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Abstract
The invention relates to the technical field of photovoltaic cells, in particular to a preparation method of a TOPCon cell local passivation contact structure. The preparation method comprises the following steps: preparing a passivation contact structure containing hydrogen on the silicon surface, and then carrying out graphic local treatment by adopting laser so that the hydrogen content in a graphic area is reduced and the graphic area has alkali corrosion resistance. The method for preparing the local passivation contact structure utilizes the mechanism that the hydrogen content of the film structure is different and the resistance to the alkali solution etching is different, and solves the technical problems that the mask preparation and removal process is complex, the pattern accuracy is poor, the later-stage metallization printing alignment is difficult, the mass production cannot be realized, the mass production cost is high, and the etching effect is poor in the prior art.
Description
Technical Field
The invention relates to the technical field of photovoltaic cells, in particular to a preparation method of a TOPCon cell local passivation contact structure.
Background
The passivation technology of the solar photovoltaic cell is continuously improved, the compounding problem of the non-metallized area is basically not the bottleneck of improving the efficiency any more, and the compounding of the metallized area becomes the bottleneck of improving the efficiency of the cell. The metallization recombination can be greatly reduced through the passivation contact structure of the cell, but the current density of the cell is reduced because the sunlight can be greatly absorbed by the light absorption characteristic of the poly layer. Therefore, it is necessary to develop a patterned local passivation contact technology, where a passivation contact exists only in a metallization region and no passivation contact exists in other regions, so as to solve the contradiction between light absorption of a poly layer and high metallization recombination, and thus a local passivation contact structure (poly finger) becomes a very potential technical method.
Although various research institutes have adopted various methods to develop technologies, no solution has been developed to enable mass production. The technical difficulty of this structure is the preparation of the mask and the precise control of the mask feature size. The existing poly finger technology is: firstly, preparing a TOPCon passivation contact layer; secondly, printing the wax grid line with alkali corrosion resistance on the passivation contact layer through graphical ink jet; etching the wax grid line serving as a mask in an alkaline solution with a certain concentration to etch off a non-grid line region to form a grid line-shaped passivation contact layer; fourthly, cleaning the mask wax grid line layer by using an acid solution; and fifthly, printing grid lines on the patterned passivation contact layer. The problem with this approach is that: the pattern precision of ink-jet printing is low, the width of line is big, is unfavorable for later stage metallization printing alignment, and it is serious simultaneously that poly finger width is too wide optical absorption.
In this regard, some solutions are provided in the prior art. For example, in CN201921593120.1, silicon nitride is used as a mask. However, additional silicon nitride mask deposition and removal steps are required, and the patterning process of silicon nitride deposition basically cannot realize mass production; also for example, CN202210099446.9 employs PVD to prepare a passivation contact layer, and a local passivation contact is formed by using a shielding effect by applying a metal shielding layer during the preparation process. Although the method of the patent is simple, the actual grid line distance of the battery is less than 1mm, and the required precision cannot be achieved by a metal shielding method; CN202110749345.7 uses the ink-jet printing paraffin as a mask, the method can prepare the battery at present, but the precision of the ink-jet printing is low, the difficulty of the subsequent screen printing overprinting is higher, simultaneously, the melting point of the paraffin is low, the sample needs to be stored at low temperature, the paraffin is used as an organic matter and needs to be cleaned, and the wet tank body is easily polluted. In the battery preparation process, the grid lines are directly printed after passivation contact, and then other areas of the passivation contact layer are etched by using the self-masking effect of the silver grid lines, but metal ions such as Ag can be etched to pollute the battery in the etching process, and carriers are led out from the grid lines due to the influence of coating, so that the method has two metal printing and sintering processes, and the mass production cost is high. In addition, CN202110163667.3 performs laser and other heat treatments on the target portion of the amorphous silicon layer to form a doped polysilicon region, and then removes the amorphous silicon region to obtain a local passivation contact structure on the front surface of the silicon substrate, but in practical applications, the etching rate of alkali on the amorphous silicon is lower than that of polysilicon, which may cause the alkali etching removed portion to be a laser processed region and leave a laser unprocessed region, and this method cannot achieve the ideal processing effect of removing the laser unprocessed region and leaving the laser processed region.
Disclosure of Invention
In view of the above, the present invention finds that when the laser is used for heat treatment, amorphous silicon in a target region is easily completely converted into polysilicon, so that the difference between the hydrogen ion contents in the amorphous silicon region and the polysilicon region is not significant enough, and the difference between the etching rates during subsequent etching is small, thereby affecting the etching effect.
The invention provides a method for preparing a local passivation contact structure, and solves the technical problems that mask preparation and removal processes are complex, the pattern accuracy is poor, later-stage metallization printing alignment is difficult, mass production cannot be achieved, the mass production cost is high, and the etching effect is poor in the prior art.
Firstly, the invention provides a preparation method of a local passivation contact structure, which comprises the following steps:
preparing a passivation contact structure containing hydrogen on the silicon surface, and then carrying out graphic local processing by adopting laser, so that the hydrogen content in a graphic area is reduced, and the silicon wafer has alkali corrosion resistance.
Preferably, the difference of the hydrogen content in the pattern area is more than 5% before and after the patterning local processing by the laser.
As a preferred embodiment of the present invention, the passivation contact structure is a SiOx-doped amorphous silicon Si structure.
As a preferred embodiment of the present invention, the patterning local treatment is performed at a laser wavelength of 500 to 550 nm and an energy density of 4 to 15 joules per square centimeter.
As a preferred embodiment of the present invention, the patterning local treatment is performed using a laser at a laser wavelength of 530 to 550 nm and an energy density of 10 to 15 joules per square centimeter.
As a preferred embodiment of the invention, when the laser is adopted for the graphic local processing, the pulse width is 3-50 nanoseconds; and/or the laser spot is square, and the side length of the square is less than or equal to 70 micrometers; and/or the distance between the centers of the light spots is less than or equal to the side length of the shape of the light spots.
As a preferred embodiment of the present invention, the width of the laser is 50 to 100 micrometers, the width of the front metal grid line is 5 to 30 micrometers, the width of the metal grid line is less than the width of the local passivation contact structure, and the laser processing pattern is consistent with the screen printing pattern.
As a preferred embodiment of the present invention, in Ar, N 2 、O 2 、N 2 O、O 3 Performing graphical local processing by using laser in an atmosphere environment of at least one of the above.
As a preferred embodiment of the present invention, a SiOx-doped amorphous silicon Si structure is prepared by PECVD in an argon or hydrogen atmosphere at 400 to 500 ℃, preferably, in the preparation of the doped amorphous silicon Si structure, the flow ratio of argon or hydrogen to silane is controlled to be 1 to 8:1. more preferably, the flow ratio of argon or hydrogen to silane is controlled to be 1-4: 1.
as a preferred embodiment of the present invention, the SiOx has a thickness of 1 to 2 nm;
and/or the thickness of the doped amorphous silicon Si structure is more than 100 nanometers;
and/or the doping element in the doped amorphous silicon Si structure is at least one of B, al, ga and P;
and/or in the doped amorphous silicon Si structure, the atom number of the doping elements in each cubic centimeter is more than or equal to 1 multiplied by 10 18 And (4) respectively.
As a preferred embodiment of the present invention, after the patterning local processing is performed by using a laser, the preparation method further comprises: etching the treated sample in an alkali solution, and then annealing, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure;
or after the laser is adopted for graphic local processing, the preparation method further comprises the following steps: and annealing the treated sample, then etching in an alkali solution, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure.
In a preferred embodiment of the present invention, the alkali solution contains at least one of KOH, naOH, and TMAH;
and/or the alkali solution contains an etching additive;
and/or the film layer subjected to film coating passivation treatment is at least one of SiOx, siNx, siNOx and AlOx;
and/or the thickness of the film layer after the film coating passivation treatment is 50-90 nanometers;
and/or the annealing temperature is 780-920 ℃.
Further, the present invention provides a method for manufacturing a solar cell, comprising: the local passivation contact structure is prepared on the front surface of the battery by adopting the preparation method of the local passivation contact structure in any one of the above embodiments, and then hydrogen passivation treatment is carried out.
In a preferred embodiment of the present invention, the hydrogen passivation treatment has a light intensity of 20000 kilowatts per square meter or more and a temperature of 200 to 700 ℃.
Furthermore, the invention also provides a solar cell which contains the local passivation contact structure prepared by the preparation method or is prepared by the preparation method of the solar cell.
The invention has the beneficial effects that:
the method for preparing the local passivation contact structure utilizes the mechanism that the hydrogen content of the film structure is different and the resistance to the alkali solution etching is different, and solves the technical problems that the mask preparation and removal process is complex, the pattern accuracy is poor, the later-stage metallization printing alignment is difficult, the mass production cannot be realized, the mass production cost is high, and the etching effect is poor in the prior art.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below, and it should be apparent that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As an embodiment of the present invention, this embodiment provides a method for manufacturing a local passivation contact structure, including: preparing a passivation contact structure containing hydrogen on the silicon surface, and then carrying out graphic local processing by adopting laser, so that the hydrogen content in a graphic area is reduced, and the silicon wafer has alkali corrosion resistance.
The invention discovers that a passivation contact structure containing hydrogen is prepared on the surface of a silicon wafer, then laser is used for patterning, so that hydrogen in a target area can be greatly excited and then escapes from a silicon film, amorphous silicon (7-15%) with high hydrogen content in the target area is converted into amorphous silicon with low/zero (less than or equal to 2%) hydrogen content, and a silicon layer in the target area has stronger etching resistance to alkali solution.
Specifically, the etching rate of the alkali solution to the laser-processed silicon film layer is far less than that of the unprocessed silicon film layer, so that the etching rates of the laser-processed region and the unprocessed region are greatly different, and the etching effect is remarkably improved. The laser-treated silicon layer can be used as a mask, then the non-laser-treated area is removed through alkali etching, the laser-treated area is reserved, and the local passivation contact structure can be obtained through acid cleaning.
Meanwhile, the preparation method provided by the invention has the advantages of high precision, adjustable width of the passivated contact area, simple process, mass production capability and battery efficiency improvement capability, and solves the problems of complex mask preparation and removal process, poor pattern precision, difficulty in later-stage metallization printing alignment and the like. The preparation is carried out by adopting a laser process, the precision of the preparation is far higher than that of other thin film deposition processes, and a window is provided for the accuracy of the subsequent screen printing overprinting.
As an embodiment of the invention, the hydrogen content difference of the graphic area is more than 5% before and after the graphic area processing by the laser.
The passivation contact structure containing hydrogen includes, but is not limited to, aluminum oxide-polysilicon passivation contact structure, siO x N y -a polysilicon passivation contact structure, siOx-doped amorphous silicon Si structure. Other hydrogen-containing passivated contact structures that are capable of achieving passivated contact performance are also within the scope of the present invention.
As an embodiment of the invention, the passivation contact structure is a SiOx-doped amorphous silicon, si, structure.
As an embodiment of the present invention, the patterning local process is performed at a laser wavelength of 500-550 nm and an energy density of 4-15 joules per square centimeter.
As an embodiment of the invention, the patterning local processing is carried out by using laser at the laser wavelength of 530-550 nanometers and the energy density of 10-15 joules per square centimeter.
And the graphical local processing is carried out under the laser parameters, so that the hydrogen escape effect of the graphical area is better, the hydrogen content of the laser processing area and the non-processing area is further improved, and the subsequent etching effect is better.
As an embodiment of the invention, when the laser is adopted for the graphic local processing, the pulse width is 3-50 nanoseconds; and/or the laser spot is square, and the side length of the square is less than or equal to 70 micrometers; and/or the distance between the centers of the light spots is less than or equal to the side length of the shape of the light spots.
Under the pulse width, laser power, the laser wavelength of above-mentioned laser, because laser wavelength is longer to be favorable to laser to penetrate whole silicon membranous layer and handle silicon, laser energy density height has enough energy to break the H bond release hydrogen in the silicon membranous layer simultaneously, and the pulse width broad can promote the effect time of laser to the silicon membranous layer for hydrogen has enough release time. After treatment, the alkali etching rate of the target area is less than or equal to 5nm/min, while the etching rate of the non-treatment area is more than or equal to 50nm/min.
As an embodiment of the invention, the width of the laser is 50-100 microns, the width of the front metal grid line is 5-30 microns, the width of the metal grid line is less than the width of the local passivation contact structure, and a laser processing pattern is consistent with a screen printing pattern.
As an embodiment of the invention, in Ar, N 2 、O 2 、N 2 O、O 3 Performing graphical local processing by using laser under the atmosphere environment of at least one of the above.
By carrying out laser treatment in the atmosphere, the modification of the silicon film layer can be assisted, and the hydrogen can be promoted to further escape out of the silicon layer, so that the difference of the hydrogen content of a laser treatment area and an unprocessed area is larger, and the remarkable improvement of the etching effect is facilitated.
As an embodiment of the invention, in argon or H 2 Preparing SiOx-doped amorphous silicon Si structure by PECVD at 400-500 ℃.
The invention also discovers that the SiOx-doped amorphous silicon Si structure is prepared by adopting a PECVD mode, the silicon layer is amorphous and has high hydrogen content, and further after laser treatment of the parameters, the hydrogen content difference between a laser treated area and an untreated area can be larger, so that the etching rate is larger, and the etching effect is further improved.
As an embodiment of the invention, in the preparation of the doped amorphous silicon Si structure, the flow ratio of argon or hydrogen to silane in the PECVD process is controlled to be 1-8: 1. more preferably, the flow ratio of argon or hydrogen to silane is controlled to be 1-4: 1.
as an embodiment of the present invention, the SiOx has a thickness of 1 to 2 nm;
and/or the thickness of the doped amorphous silicon Si structure is more than 100 nanometers;
and/or the doping element in the doped amorphous silicon Si structure is at least one of B, al, ga and P;
and/or in the doped amorphous silicon Si structure, the atomic number of the doping element in each cubic centimeter is more than or equal to 1 multiplied by 10 18 And (4) respectively.
As an embodiment of the present invention, after performing the graphic local processing by using the laser, the preparation method further includes: etching the treated sample in an alkali solution, and then annealing, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure;
or after the laser is adopted for graphic local processing, the preparation method further comprises the following steps: and annealing the treated sample, then etching in an alkali solution, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure.
As an embodiment of the invention, an n-type monocrystalline silicon wafer is adopted, texturing, boron diffusion or phosphorus diffusion treatment and cleaning treatment are carried out on the monocrystalline silicon wafer, and then a SiOx-doped amorphous silicon Si structure is prepared on the surface of the cleaned silicon wafer.
As an embodiment of the invention, the alkaline solution contains at least one of KOH, naOH and TMAH;
and/or the alkali solution contains an etching additive;
and/or the film layer subjected to film coating passivation treatment is at least one of SiOx, siNx, siNOx and AlOx;
and/or the thickness of the film layer after the film coating passivation treatment is 50-90 nanometers;
and/or the annealing temperature is 780-920 ℃.
Preferably, the annealing time is 20 to 50min.
Annealing under the above conditions can further activate the doping elements in the localized SiOx-doped amorphous silicon Si structure and promote crystallization.
In any embodiment of the invention, the alkali content in the alkali solution is 3-40wt%.
As an embodiment of the present invention, this embodiment provides a method for manufacturing a solar cell, including: the local passivation contact structure is prepared on the front surface of the battery by adopting the preparation method of the local passivation contact structure of any one of the embodiments, and then hydrogen passivation treatment is carried out.
As an embodiment of the invention, the light intensity of the hydrogen passivation treatment is more than 20000 kilowatts per square meter, and the temperature is 200-700 ℃. Preferably, the time of the hydrogen passivation treatment is 5min or more.
As a preferred embodiment of the present invention, a method for manufacturing a solar cell includes:
(1) Using an n-type monocrystalline silicon wafer, performing texturing, boron diffusion or phosphorus diffusion on the n-type monocrystalline silicon wafer, removing a region of a back surface around a plating diffusion layer, and then performing acid washing to obtain a cleaning silicon wafer;
(2) Preparing a SiOx-doped amorphous silicon Si structure on the front surface of a cleaned silicon wafer, and then carrying out graphical local processing by adopting laser at the laser wavelength of 500-550 nm and the energy density of 4-15 joules per square centimeter;
(3) Carrying out alkali etching on the processed silicon wafer;
(4) Preparing a SiOx-phosphorus doped amorphous silicon Si structure on the back of the silicon wafer;
(5) Annealing the treated sample, and then performing film coating passivation treatment on the front side of the silicon wafer;
(6) Depositing a passivation film on the back of the silicon wafer;
(7) Overprinting metal slurry on the front surface of the silicon wafer and sintering to form a local passivation contact structure; simultaneously printing a silver metal grid line on the back and synchronously sintering the silver metal grid line on the front;
(8) And carrying out hydrogen passivation treatment to obtain the solar cell.
The present embodiment also provides, as an embodiment of the present invention, a solar cell, which contains the local passivation contact structure prepared by the above preparation method, or is prepared by the above preparation method of the solar cell.
Because the solar cell adopts the preparation method to prepare the local passivation contact structure, the etching rate difference of different areas is larger, the passivation contact of the metalized area can be completely reserved, the metalized area composition of the photovoltaic cell can be greatly reduced, the passivation contact structure of the non-metalized area can be completely removed, the related negative influence of parasitic absorption is not generated, the open-circuit voltage of the solar cell is greatly increased, the short-circuit current is not reduced, and the cell performance is obviously improved.
A person skilled in the art can further combine the above embodiments to obtain other preferred embodiments of the method for preparing a locally passivated contact structure according to the invention.
The technical solution of the present invention will be described with reference to more specific examples.
The specific techniques or conditions not indicated in the examples are all conventional methods or techniques or conditions described in the literature of the field or according to the product specifications. The reagents and instruments used are conventional products which are available from normal commercial vendors, not indicated by manufacturers.
Example 1
The embodiment provides a method for preparing a local passivation contact structure, which comprises the following specific steps:
(1) Preparing a SiOx-doped amorphous silicon Si structure on the surface of the cleaned silicon wafer by adopting PECVD; specifically, the parameters of PECVD are: siOx preparation parameters: time 95s, ar gas flow rate of 2000sccm, NO 2 8000sccm of airflow, 13000 watts of power, 1/60 duty ratio and 470 ℃ of temperature; preparation parameters of the amorphous silicon-doped layer: time 1300s, H 2 10000sccm of gas flow, 2600sccm of silane flow, 3.85 of hydrogen flow/silane flow, 1000sccm of borane flow, 14000 watts of power and 6/60H of duty cycle 2 The deposition temperature was 470 ℃.
(2) Carrying out graphical local processing by adopting laser; the laser wavelength is 532 nm, the energy density is 10 joules per square centimeter, the pulse width is 20ns, the laser spot shape is square, the side length of the square is 70 microns, and the spot center distance is less than or equal to the side length of the spot shape; the treatment atmosphere is normal pressure, and the volume ratio of oxygen is 75%. The width of the laser is 70 microns, the width of the front metal grid line is 25 microns, the width of the metal grid line is smaller than the width of the local passivation contact structure, and a laser processing pattern is consistent with a screen printing pattern.
(3) And (3) immersing the processed silicon wafer into 30wt% KOH alkaline solution for etching, wherein the etching time is 300s, and the solution temperature is 65 ℃.
(4) And annealing the sample at 920 ℃ for 50min.
(5) And passivating the surface of the sample by depositing an aluminum oxide/silicon nitride double-layer film. The deposition temperature of alumina was 200 ℃ and the film thickness was 8nm. The deposition temperature of silicon nitride is 500 ℃, the flow of ammonia gas/the flow of silane is 11.5, the deposition time is 2800s, and the film thickness is 75nm.
(6) Overprinting silver-aluminum metal paste in the local passivation region, wherein the printing width of the metal paste is 25 microns, and sintering at 740 ℃ to form a local passivation contact structure;
further, this embodiment provides a solar cell having the above local passivation contact structure, and the preparation method thereof is as follows:
(7) The silicon wafer used was an n-type single crystal silicon wafer having a resistivity of 1.5 Ω "cm. The silicon wafers were subjected to the texturing treatment before the above step (1), using a 2% by weight KOH solution, at a temperature of 80 ℃ for a treatment time of 6min.
(8) And (3) performing boron diffusion treatment on the silicon wafer after the texturing, wherein the diffusion temperature is 1000 ℃, the diffusion time is 58min, and the diffusion sheet resistance is 235 omega/\9633.
(9) And (3) treating the back surface and the periphery of the diffused silicon wafer by using KOH solution with the concentration of 15 percent by weight at 82 ℃ for 3min to remove the boron-plated diffusion layer region, and carrying out HF acid cleaning to obtain the cleaned silicon wafer required by the step (1), wherein the step (1) to the step (3) are completed on the front surface of the silicon wafer.
(10) Preparing a SiOx-phosphorus doped amorphous silicon Si structure on the back of the cleaned silicon wafer by adopting PECVD; specifically, the parameters of PECVD are: siOx preparation parameters: time 95s, ar gas flow rate of 2000sccm, NO 2 8000sccm of airflow, 13000 watts of power, 1/60 duty ratio and 470 ℃ of temperature; preparation parameters of the phosphorus-doped amorphous silicon layer: time 1300s, H 2 10000sccm of gas flow, 2600sccm of silane flow, 3.85 of hydrogen flow/silane flow, 1000sccm of phosphine flow, 14000 watts of power and 6/60H of duty ratio 2 The deposition temperature was 470 ℃.
(11) And (5) finishing the steps (4) to (5).
(12) Depositing a passivation film on the back surface of the battery, wherein the passivation film is SiN x /SiO 2 And the total thickness of the laminated structure is 75nm.
(13) And (6) printing a silver metal grid line on the other surface of the battery and synchronously sintering the front silver-aluminum grid line in the step (6).
(14) And performing hydrogen passivation treatment, wherein the light intensity of the hydrogen passivation treatment is 20000 kilowatts per square meter, and the temperature is 350 ℃, so as to obtain the solar cell.
Example 2
The embodiment provides a method for preparing a local passivation contact structure, which only differs from embodiment 1 in the following specific steps:
and (4) exchanging the sequence of the steps.
Further, this example provides a solar cell having the above-mentioned local passivation contact structure, and the preparation method is different from example 1 only in the sequence of the above-mentioned steps (3) and (4).
Example 3
The embodiment provides a method for preparing a local passivation contact structure, which only differs from embodiment 1 in the following specific steps:
in the deposition process of PECVD, H in the deposition of an amorphous silicon film layer 2 In the atmosphere H 2 The gas flow was 20800sccm and the hydrogen flow/silane flow was 8.
Further, this embodiment provides a solar cell having the above local passivation contact structure, and the preparation method is different from that of embodiment 1 only in the deposition parameters of the amorphous silicon film layer.
Example 4
The embodiment provides a method for preparing a local passivation contact structure, which only differs from embodiment 1 in the following specific steps:
in the PECVD deposition process, ar atmosphere is adopted in the deposition of the amorphous silicon film layer, wherein the Ar gas flow is 9000sccm, and the Ar gas flow/silane flow is 3.46.
Further, this embodiment provides a solar cell having the above local passivation contact structure, and the preparation method is different from that of embodiment 1 only in the deposition parameters of the amorphous silicon film layer.
Example 5
The embodiment provides a method for preparing a local passivation contact structure, which only differs from embodiment 1 in the following specific steps:
the laser wavelength was 550 nm and the energy density was 15 joules per square centimeter.
Further, this example provides a solar cell having the above locally passivated contact structure, which is fabricated by a method different from example 1 only in the wavelength and energy density of the laser described above.
Example 6
The embodiment provides a method for preparing a local passivation contact structure, which only differs from embodiment 1 in the following specific steps:
the laser wavelength was 500 nm and the energy density was 4 joules per square centimeter.
Further, this example provides a solar cell having the above-described locally passivated contact structure, which was fabricated using a method that differed from example 1 only in the above-described laser wavelength and energy density.
Comparative example
The comparative example provides a method for preparing a local passivation contact structure, which only differs from example 1 in the following specific steps:
(1) Preparation of SiOx-doped amorphous silicon Si layer: the SiOx-doped amorphous silicon Si layer is prepared by in-situ doping, specifically, LPCVD parameters are: the oxidation deposition temperature is 605 ℃, the deposition time is 600s, and the oxygen flow is 3.6 multiplied by 10 5 sccm; the deposition temperature of the doped amorphous silicon layer is 610 ℃, the flow rate of silane is 2240sccm, and the small nitrogen (carrying BCl) 3 ) Flow 970scm, time 1900s.
(2) Laser processing: the laser wavelength was 532 nm, the energy density was 0.5 joules per square centimeter, the treatment atmosphere was water vapor, and the water vapor flow was 200sccm.
Further, this example provides a solar cell having the above-described local passivation contact structure, which is prepared by a method different from the method of example 1, in which only the SiOx-doped amorphous silicon Si layer is prepared and the laser processing step is performed.
Test examples
The laser processing target areas prepared in the above examples and comparative examples were subjected to alkali-resistant etching test.
The specific test method comprises the following steps: preparing SiOx-doped silicon film on the surface of the polished silicon wafer according to the preparation method,testing the thickness d of a silicon film 0 (ii) a Carrying out regional laser processing on the corresponding laser parameters; immersing the treated sample in 30wt% KOH solution for 5min, and testing the thickness d of the residual silicon film in the target area of laser treatment 1 And d of the non-laser-treated region 2 (ii) a Calculating to obtain the alkali etching rate S1 of the silicon film in the laser processing target area and the alkali etching rate S2 of the silicon film in the non-laser processing area; the etching rate ratio S2/S1 is used as an evaluation index, and the larger the ratio is, the stronger the selective etching is, which is a better technical scheme.
The test results are shown in table 1.
TABLE 1 Experimental results of different examples
The solar cells prepared in the above examples and comparative examples were tested. 200 pieces were tested per example and the results averaged.
The IV curve is specifically tested and the cell open circuit voltage Voc, the short circuit current density Jsc, the fill factor FF and the cell photoelectric conversion efficiency Eff are determined.
The results are shown in Table 2.
TABLE 2 test results of experiment IV of different examples
| Eff(％) | Voc(mV) | Jsc(mA/cm 2 ) | FF(％) | |
| Example 1 | 25.33 | 725 | 41.6 | 84 |
| Example 2 | 25.20 | 723 | 41.5 | 84 |
| Example 3 | 25.15 | 725 | 41.3 | 84 |
| Example 4 | 25.21 | 725 | 41.4 | 84 |
| Example 5 | 25.15 | 725 | 41.3 | 84 |
| Example 6 | 24.99 | 722 | 41.2 | 84 |
| Comparative example | 24.92 | 720 | 41.2 | 84 |
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (12)
1. A method for preparing a locally passivated contact structure, comprising:
preparing a passivation contact structure containing hydrogen on the silicon surface, and then carrying out graphic local processing by adopting laser, so that the hydrogen content in a graphic area is reduced, and the silicon wafer has alkali corrosion resistance.
2. The method of claim 1, wherein the passivation contact structure is a SiOx-doped amorphous silicon (Si) structure.
3. The method of claim 1 or 2, wherein the patterning is performed at a laser wavelength of 500-550 nm and an energy density of 4-15 joules per square centimeter.
4. The method for preparing a local passivation contact structure according to any one of claims 1 to 3, characterized in that, when the laser is used for the graphic local processing, the pulse width is 3 to 50 nanoseconds; and/or the laser spot is square, and the side length of the square is less than or equal to 70 microns; and/or the distance between the centers of the light spots is less than or equal to the side length of the shape of the light spots.
5. The method for preparing a local passivation contact structure according to any of claims 1 to 4, wherein the width of the laser is 50 to 100 microns, the width of the front metal grid line is 5 to 30 microns, the width of the metal grid line is less than the width of the local passivation contact structure, and the laser processing pattern is consistent with the screen printing pattern.
6. The method of any of claims 1-5, wherein Ar, N are in contact with the passivation layer 2 、O 2 、N 2 O、O 3 Performing graphical local processing by using laser in an atmosphere environment of at least one of the above.
7. The method of making a locally passivated contact structure according to any of claims 2 to 6 wherein the SiOx has a thickness in the range of 1 to 2 nm;
and/or the thickness of the doped amorphous silicon Si structure is more than 100 nanometers;
and/or the doping element in the doped amorphous silicon Si structure is at least one of B, al, ga and P;
and/or in the doped amorphous silicon Si structure, the atom number of the doping elements in each cubic centimeter is more than or equal to 1 multiplied by 10 18 And (4) respectively.
8. Method for producing a locally passivated contact structure according to any of claims 2 to 7, characterized in that the SiOx-doped amorphous silicon Si structure is produced by PECVD in an argon or hydrogen atmosphere at 400-500 ℃, preferably in the production of doped amorphous silicon Si structure, the flow ratio of argon or hydrogen to silane is controlled to be 1-8: 1.
9. the method of fabricating a locally passivated contact structure according to any of claims 1 to 8, wherein after the patterning local process with the laser, the method further comprises: etching the treated sample in an alkali solution, and then annealing, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure;
or after the laser is adopted for graphic local processing, the preparation method also comprises the following steps: and annealing the treated sample, then etching in an alkali solution, coating passivation, overprinting metal slurry and sintering to form a local passivation contact structure.
10. The method for preparing a local passivation contact structure according to claim 9, wherein the alkali solution contains at least one of KOH, naOH, and TMAH;
and/or the alkali solution contains an etching additive;
and/or the film layer subjected to film coating passivation treatment is at least one of SiOx, siNx, siNOx and AlOx;
and/or the thickness of the film layer after the film coating passivation treatment is 50-90 nanometers;
and/or the annealing temperature is 780-920 ℃.
11. A method for manufacturing a solar cell, comprising: preparing a local passivation contact structure on the front surface of the battery by adopting the preparation method of the local passivation contact structure as claimed in any one of claims 1 to 10, and then performing hydrogen passivation treatment; the light intensity of the hydrogen passivation treatment is more than 20000 kilowatts per square meter, and the temperature is 200-700 ℃.
12. A solar cell comprising a locally passivated contact structure produced by the method of any one of claims 1 to 10 or produced by the method of claim 11.
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