CN115241083A - Method for rapidly monitoring stability of polishing solution - Google Patents
Method for rapidly monitoring stability of polishing solution Download PDFInfo
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- CN115241083A CN115241083A CN202210908061.2A CN202210908061A CN115241083A CN 115241083 A CN115241083 A CN 115241083A CN 202210908061 A CN202210908061 A CN 202210908061A CN 115241083 A CN115241083 A CN 115241083A
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 64
- 238000005498 polishing Methods 0.000 title claims abstract description 62
- 238000000034 method Methods 0.000 title claims abstract description 55
- 238000012360 testing method Methods 0.000 claims abstract description 42
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 40
- 239000010703 silicon Substances 0.000 claims abstract description 40
- 238000009792 diffusion process Methods 0.000 claims abstract description 39
- 238000004140 cleaning Methods 0.000 claims abstract description 32
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 26
- 239000011574 phosphorus Substances 0.000 claims abstract description 26
- CMWTZPSULFXXJA-VIFPVBQESA-N naproxen Chemical compound C1=C([C@H](C)C(O)=O)C=CC2=CC(OC)=CC=C21 CMWTZPSULFXXJA-VIFPVBQESA-N 0.000 claims abstract description 25
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 19
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 19
- 238000000151 deposition Methods 0.000 claims abstract description 16
- 238000005245 sintering Methods 0.000 claims abstract description 16
- 229910021421 monocrystalline silicon Inorganic materials 0.000 claims abstract description 13
- 230000003750 conditioning effect Effects 0.000 claims abstract description 10
- 238000001035 drying Methods 0.000 claims abstract description 8
- 239000000243 solution Substances 0.000 claims description 62
- 239000002253 acid Substances 0.000 claims description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 239000008367 deionised water Substances 0.000 claims description 7
- 229910021641 deionized water Inorganic materials 0.000 claims description 7
- 230000008021 deposition Effects 0.000 claims description 7
- 238000001514 detection method Methods 0.000 claims description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- 239000003513 alkali Substances 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 6
- 238000000746 purification Methods 0.000 claims description 6
- 239000000654 additive Substances 0.000 claims description 5
- 238000002310 reflectometry Methods 0.000 claims description 4
- 230000002441 reversible effect Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 claims description 3
- 230000000996 additive effect Effects 0.000 claims description 2
- 230000001737 promoting effect Effects 0.000 abstract description 3
- 235000012431 wafers Nutrition 0.000 description 40
- 210000004027 cell Anatomy 0.000 description 14
- 239000010408 film Substances 0.000 description 11
- 238000002161 passivation Methods 0.000 description 10
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- 229910052796 boron Inorganic materials 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 238000002474 experimental method Methods 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000007517 polishing process Methods 0.000 description 4
- 229910052814 silicon oxide Inorganic materials 0.000 description 4
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 238000007796 conventional method Methods 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 230000003287 optical effect Effects 0.000 description 3
- 238000004804 winding Methods 0.000 description 3
- 239000000969 carrier Substances 0.000 description 2
- 239000003814 drug Substances 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 238000009776 industrial production Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 2
- 238000007747 plating Methods 0.000 description 2
- 229910021420 polycrystalline silicon Inorganic materials 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000007650 screen-printing Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 230000001052 transient effect Effects 0.000 description 2
- 230000005856 abnormality Effects 0.000 description 1
- 230000005587 bubbling Effects 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 230000009191 jumping Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000013386 optimize process Methods 0.000 description 1
- 229920005591 polysilicon Polymers 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005204 segregation Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000005641 tunneling Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/30—Structural arrangements specially adapted for testing or measuring during manufacture or treatment, or specially adapted for reliability measurements
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67242—Apparatus for monitoring, sorting or marking
- H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
- H01L22/10—Measuring as part of the manufacturing process
- H01L22/14—Measuring as part of the manufacturing process for electrical parameters, e.g. resistance, deep-levels, CV, diffusions by electrical means
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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
- H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Microelectronics & Electronic Packaging (AREA)
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- Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- General Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Testing Or Measuring Of Semiconductors Or The Like (AREA)
Abstract
The invention relates to the technical field of battery polishing, and particularly discloses a method for rapidly monitoring the stability of a polishing solution. The method comprises the following steps: taking a P-type monocrystalline silicon wafer as a conditioning piece, carrying out pre-cleaning, then carrying out double-sided polishing on the conditioning piece for 2-4 min at the temperature of 50-55 ℃ by adopting a polishing solution, then carrying out post-cleaning, and drying to obtain a polished silicon wafer; performing double-sided phosphorus diffusion on the polished silicon wafer to obtain a phosphorus diffusion silicon wafer; depositing silicon nitride antireflection films on the front surface and the back surface of the phosphorus diffusion silicon wafer respectively, and sintering to obtain a monitoring wafer; and carrying out a Sinton test on the monitoring piece. The invention simplifies the process steps of the monitoring sheet, can directly judge whether the polishing solution is deteriorated or not according to the result of the Sinton test, obviously reduces the time for monitoring, has accurate judgment result, and has important significance for promoting the industrialized popularization of TOPCon batteries and avoiding the generation of unqualified batteries and low-efficiency batteries.
Description
Technical Field
The invention relates to the technical field of battery polishing, in particular to a method for rapidly monitoring stability of a polishing solution.
Background
N-type solar cells are the focus of research due to their excellent stability and higher efficiency potential. The TOPCon cell is a new type of N-type solar cell that uses an ultra-thin oxide layer and doped thin film silicon on the cell surface for passivation. The ultrathin silicon oxide reduces the surface state, keeps lower tunneling resistance, and is doped with thin film silicon, so that field passivation is provided, carriers selectively penetrate through the silicon oxide, a good passivation contact is formed with a silicon substrate, and the ultrathin silicon oxide becomes the development trend of the current high-efficiency battery.
The Topcon battery process flow comprises the following steps: alkali texturing; b, front boron diffusion; removing and cleaning the back surface by diffusion; polishing the back surface; depositing an ultrathin oxide layer on the back and polysilicon; back phosphorus doping; removing glass on the front surface; removing the winding plating on the front surface; passivating aluminum oxide; silicon nitride antireflection; screen printing; and (5) sintering. Namely, the back surface of the cell needs to be polished in the production process of the TOPCon cell, and the back surface passivation treatment can be carried out after the polishing treatment, so that whether the back surface polishing process is stable or not greatly influences the back surface passivation effect of the TOPCon cell, thereby influencing the efficiency of the TOPCon cell. The stability of the polishing solution directly affects the polishing effect, and once the polishing solution is contaminated or the conditions are not satisfied, the passivation performance of the battery is damaged, so that a large batch of TOPCon unqualified batteries or low-efficiency batteries are generated.
At present, a silicon wafer with the back surface removed and cleaned by diffusion is used as a monitoring wafer, the Topcon battery is produced by using the normal process flow, and then whether the polishing solution is normal or not is judged by monitoring the battery efficiency of the Topcon battery. However, the process is complicated, the process time is over 7 hours, if abnormality cannot be found in time, performance of batteries in batches can be reduced, even batch unqualified phenomena can be caused, and the process has great influence on industrial production. In addition, the silicon wafer after the back surface diffusion removal cleaning is adopted as a monitoring wafer at present, and the monitoring wafer is subjected to texturing, boron diffusion, back surface diffusion removal cleaning and other 3 process links, and the instability of the three process links can also cause misjudgment on the stability of the polishing solution.
Therefore, it is urgently needed to find a method for rapidly monitoring the stability of the polishing solution, which is significant for promoting the industrialization popularization of the TOPCon battery and improving the qualification rate of the TOPCon battery.
Disclosure of Invention
In view of the above, the invention provides a method for rapidly monitoring the stability of a polishing solution, which is characterized in that a monitoring piece is prepared by adopting 4 steps of double-sided polishing, double-sided phosphorus diffusion, silicon nitride antireflection, sintering and the like, so that the monitoring time is greatly reduced, the generation of unqualified batteries or low-efficiency batteries is avoided, and the effects of timely finding problems and adjusting a production line are achieved.
In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:
a method for rapidly monitoring the stability of polishing solution, which comprises the following steps:
firstly, taking a P-type monocrystalline silicon wafer as a conditioning piece, carrying out pre-cleaning, then carrying out double-side polishing on the conditioning piece for 2-4 min at 50-55 ℃ by adopting a polishing solution, and then carrying out post-cleaning and drying to obtain a polished silicon wafer;
secondly, performing double-sided phosphorus diffusion on the polished silicon wafer to obtain a phosphorus diffusion silicon wafer;
depositing silicon nitride antireflection films on the front surface and the back surface of the phosphorus diffusion silicon wafer respectively, and sintering to obtain a monitoring wafer;
and step four, carrying out a Sinton test on the monitoring sheet.
Compared with the prior art, the method for rapidly monitoring the stability of the polishing solution has the following advantages:
the applicant finds that, if an N-type monocrystalline silicon wafer is used as a test piece and a PN junction is formed by boron diffusion, the result of testing the minority carrier lifetime, the reverse saturation current density (J0) and the open-circuit voltage (iVoc) of a Sinton test has a large error, and further the judgment of the stability of the polishing solution is influenced, and the result is probably caused because the diffusion coefficient of boron atoms in the silicon wafer is extremely low (only 1.3 at 1200 ℃), so that the uniformity of boron diffusion into the silicon wafer is not easy to control, and the result of testing the open-circuit voltage and the reverse saturation current density has a large error; in addition, the segregation coefficient of impurities in boron-diffused silicon dioxide is too low, so that the impurities are not easy to precipitate out to a silicon oxide layer at high temperature, more impurities are remained in silicon, and the test results of the minority carrier lifetime and the open-circuit voltage are influenced.
Therefore, in order to ensure the accuracy of the Sinton test result, the monitoring piece is prepared by taking the P-type monocrystalline silicon wafer as a regulating piece and only adopting 4 steps of double-sided polishing, double-sided phosphorus diffusion, silicon nitride antireflection, sintering and the like, and an ion layer with charges of different polarities, namely a P-N junction, which cannot move is formed on two sides of an interface through the phosphorus diffusion, so that additional photogenerated carriers are generated, the conductivity of the P-type monocrystalline silicon wafer is changed, and the smooth performance of the Sinton test is ensured; then, silicon nitride deposition is carried out to realize hydrogen passivation, and sintering is carried out to avoid the problem of silicon wafer surface pollution in the transfer or contact link, so as to ensure the accuracy of the Sinton test.
The invention simplifies the process steps of the monitoring sheet, can directly judge whether the polishing solution is deteriorated or not according to the result of the Sinton test, obviously reduces the time for monitoring, has accurate judgment result, and has important significance for promoting the industrialized popularization of TOPCon batteries and avoiding the generation of unqualified batteries and low-efficiency batteries.
Optionally, the resistivity of the P-type monocrystalline silicon wafer is 1.5 Ω · cm to 1.7 Ω · cm.
The battery efficiency is stably changed through the resistivity of the optimized monocrystalline silicon piece, so that the accuracy of the monitoring method is improved, and the situation that the battery efficiency is obviously reduced and the efficiency fluctuation range is large due to the fact that the resistivity of the P-type monocrystalline silicon piece is not appropriate, and the accuracy of the monitoring result is influenced is avoided.
Optionally, in the step one, the concentration of the alkali in the polishing solution is 1.5wt% to 2.0wt%, and the alkali is KOH or NaOH.
Optionally, in the step one, the concentration of the additive in the polishing solution is 0.4wt% to 0.6wt%.
According to the method, the optimal concentration of the polishing solution is adopted, so that the preparation process of the monitoring sheet is met, and the accurate result of the prepared monitoring sheet in the Sinton test is ensured.
The polishing solution provided by the application comprises alkali liquor and additives, wherein the additives are commonly used in the field and include, but are not limited to, additives from Topo technologies and Inc. with the types of BP51V05, BP65V14 or BP65V19 respectively.
Optionally, in the polishing process, the tank body is internally provided with a circulating and bubbling mode to ensure the uniformity of the polishing solution, so that the polishing process is smoothly performed.
Optionally, in the step one, the pre-cleaning includes sequentially using a solution containing KOH and H 2 O 2 The aqueous solution is cleaned for 1min to 2min at the temperature of 50 ℃ to 55 ℃, and then is cleaned by deionized water, wherein the concentration of KOH in the aqueous solution is 1wt percent to 1.5wt percent; h in the aqueous solution 2 O 2 The concentration of (b) is 5wt% to 6wt%.
The catalyst comprises KOH and H 2 O 2 Cleaning the impurities and oxides on the surface of the silicon wafer, and then passing ionsWater washing to remove residual KOH or H on the surface of the silicon chip 2 O 2 。
Optionally, in the first step, the post-cleaning includes sequentially cleaning with a mixed acid solution for 1min to 2min, and then performing slow pull cleaning with deionized water at a temperature of 10 ℃ to 30 ℃.
Further optionally, the mixed acid solution includes HCl and HF, and a concentration of the HCl in the mixed acid solution is 4wt% to 4.5wt%, and a solubility of the HF in the mixed acid solution is 2.5wt% to 3wt%.
Further optionally, the specific process of slow pulling is as follows: and slowly lifting the debugging sheet out of the water surface, wherein the lifting time is 1-2 min.
This application washs through mixed acid solution, then adopts specific temperature's deionized water to carry out slowly to draw and wash for silicon chip surface does not have remaining water mark, and guarantees that silicon chip surface does not have the residue of polishing solution, mixed acid solution, avoids the liquid medicine pollution to influence subsequent diffusion effect.
Optionally, in the first step, the drying conditions are as follows: the temperature is 70-80 ℃, and the time is 8-10 min.
Optionally, in the first step, the surface reflectivity of the polished silicon wafer is greater than 42%.
The surface reflectivity is measured using conventional techniques, such as a D8 reflectometer test.
Optionally, the sheet resistance of the phosphorus diffusion silicon wafer is 35 Ω -40 Ω, and the uniformity is less than or equal to 3.
The P-type monocrystalline silicon wafer is used as a test piece, and a PN junction is formed on the silicon wafer through phosphorus diffusion, so that the smooth proceeding of a subsequent Sinton test is ensured.
The uniformity selection 9-point position testing method comprises the following uniformity calculation formula:
optionally, the specific process of the double-sided phosphorus diffusion is as follows:
and (3) leak detection: the pressure is less than or equal to-200 pa;
and (3) heating: the temperature is 880-890 ℃, and the pressure is less than or equal to-10 pa;
pre-purification: the temperature is 880-895 ℃, and the time is 3-5 min;
deposition: the temperature is 880-890 ℃, and the time is 25-30 min;
propelling: the temperature is 890-905 ℃ and the time is 5-8 min;
post-purification: the temperature is 700-750 ℃, and the time is 1-2 min;
cooling: the temperature is 650-700 ℃, and the time is 20-30 min.
The uniformity of phosphorus diffusion is ensured through optimized process parameters.
Optionally, the silicon nitride antireflection film has a thickness of 55nm to 65nm and a refractive index of 2% to 2.3%.
The silicon nitride antireflection film is designed to complete hydrogen passivation efficiency, so that the polished surface is effectively protected. Therefore, the invention can effectively satisfy hydrogen passivation through the optimal film thickness and refractive index of the silicon nitride film, thereby improving the accuracy of the monitoring result.
Optionally, the conditions for depositing the silicon nitride antireflection film are as follows:
NH 3 flow rate: the 1 st path is 400 +/-50 sccm, the 2 nd path and the 3 rd path are both 500 +/-50 sccm, and the 4 th, 5 th and 6 th paths are all 550 +/-50 sccm; siH 4 Flow rate: the 1 st path is 0, the 2 nd and 3 rd paths are all 300 +/-50 sccm, and the 4 th, 5 th and 6 th paths are all 200 +/-50 sccm; the microwave power of the heating chamber is 3000W-3600W, the temperature of the process chamber is 320-420 ℃, the pressure of the process chamber is 0.25 mbar-0.31 mbar, and the pulse switching ratio is 8/10.
Through the optimized deposition conditions, the monitoring sheet with specific thickness and specific reflectivity is obtained, and the purpose of accurate monitoring result is achieved.
Optionally, the sintering conditions are as follows: the belt speed is as follows: 200ipm, zone1-Zone 10 temperature of 330 ℃, 360 ℃, 500 ℃, 550 ℃, 580 ℃, 630 ℃, 810 ℃ and 860 ℃.
Optionally, the test parameters of the Sinton test include minority carrier lifetime, reverse saturation current density (J0), and open circuit voltage (iVoc).
During the Sinton test: s1, selecting a proper test mode; s2, accurately inputting the thickness, the volume resistivity, the PN type and the optical constant of the silicon wafer before measurement; s3, adjusting light intensity; and S4, testing.
The Sinton test comprises four test modes, namely QSS, generalized (1/1), transient and Generalized (1/64), and the relevant test modes are selected according to the minority carrier lifetime range. Wherein QSS is suitable for the minority carrier lifetime of less than or equal to 200 mus, the Generalized (1/1) is suitable for any range of the minority carrier lifetime, the fluctuation range is larger in the range of 100 mus-800 mus, the Transient is suitable for the minority carrier lifetime of more than 800 mus, and the Generalized (1/64) is suitable for the minority carrier lifetime of 200 mus-800 mus.
There are two ways to adjust the light intensity: the number of the optical filters is increased or decreased, and the height of the lamp holder is adjusted. The Sinton test equipment is provided with two light filters and one deep filter for adjusting the light intensity. Whether or not to add filters and which filter to select may be selected based on minority carrier lifetime. The method specifically comprises the following steps: the minority carrier lifetime is less than or equal to 50 microseconds, the light intensity is 55sun, and no optical filter is needed; the minority carrier lifetime is more than 50 mu s and less than or equal to 200 mu s, the light intensity is 35sun, and 2 light-colored filters are needed; the minority carrier lifetime is more than 200 mu s and less than or equal to 800 mu s, the light intensity is 7.5sun, and 1 dark color filter is needed; the minority carrier lifetime tau is more than 800 mus, the light intensity is 4.5sun, and 3 filters are needed.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The embodiment of the invention provides a method for rapidly monitoring the stability of polishing solution, which comprises the following steps:
selecting a P-type monocrystalline silicon wafer with the resistivity of 1.6 omega-cm as a conditioning piece, carrying out pre-cleaning, then carrying out double-side polishing on the conditioning piece for 3min at the temperature of 52 +/-1 ℃ by adopting a polishing solution, carrying out post-cleaning, and drying for 9min at the temperature of 75 ℃ to obtain the polished silicon wafer.
The pre-cleaning comprises sequentially using a cleaning solution containing KOH and H 2 O 2 The aqueous solution is cleaned for 1.5min at the temperature of 52 +/-1 ℃, and then deionized water is adopted for cleaning to remove the residue of the liquid medicine, wherein the concentration of KOH in the aqueous solution is 1.2wt%; h in the aqueous solution 2 O 2 The concentration of (B) was 5.5wt%. The post-cleaning comprises sequentially cleaning with mixed acid solution for 1.5min, and slowly pulling with deionized water at 15 deg.C for 2min; wherein the mixed acid solution comprises HCl and HF, the concentration of the HCl in the mixed acid solution is 4.2wt%, and the solubility of the HF in the mixed acid solution is 2.8wt%;
secondly, performing double-sided phosphorus diffusion on the polished silicon wafer to obtain a phosphorus diffusion silicon wafer with the sheet resistance of 40 omega and the uniformity of less than or equal to 3;
the specific process of the double-sided phosphorus diffusion comprises the following steps:
and (3) leak detection: the pressure meets-200 pa;
and (3) heating: the temperature of the five temperature zones is respectively designed to be 880 ℃, 890 ℃ and 880 ℃, the pressure is controlled to be-10 pa, and the jumping is carried out at the original temperature;
pre-purification: the temperature of the five temperature zones is respectively designed to be 880 ℃, 890 ℃, 895 ℃, 890 ℃ and 880 ℃, and the time is controlled to be 3min;
deposition: the temperatures of the five temperature zones are respectively designed to be 880 ℃, 890 ℃ and 880 ℃, and the time is controlled to be 25min;
propelling: the temperatures of the five temperature zones are respectively designed to be 890 ℃, 900 ℃, 905 ℃, 900 ℃ and 890 ℃, and the time is controlled to be 5min;
post-purification: the temperature of the five temperature zones is designed to be 700 ℃, and the time is controlled to be 1.5min;
cooling: the temperature of the five temperature zones is designed to be 700 ℃, and the time is controlled to be 25min.
Depositing a silicon nitride antireflection film with the thickness of 60nm on the front surface and the back surface of the phosphorus diffusion silicon wafer respectively, wherein the refractive index is 2.2%, and sintering to obtain a monitoring piece;
the conditions for depositing the silicon nitride antireflection film are as follows:
NH 3 flow rate: the 1 st path is 400sccm, the 2 nd path and the 3 rd path are 500sccm, and the 4 th, 5 th and 6 th paths are 550sccm; siH 4 Flow rate: the 1 st path is 0, the 2 nd and 3 rd paths are all 300sccm, and the 4 th, 5 th and 6 th paths are all 200sccm; the microwave power of the heating chamber is 3300W, the temperature of the process chamber is 370 ℃, the pressure of the process chamber is 0.28mbar, and the pulse switching ratio is 8/10.
The sintering conditions are as follows: the belt speed is as follows: 200ipm, zone1-Zone 10 temperature of 330 ℃, 360 ℃, 500 ℃, 550 ℃, 580 ℃, 630 ℃, 810 ℃ and 860 ℃.
And step four, carrying out a Sinton test on the monitoring sheet.
In order to better illustrate the technical solution of the present invention, further comparison is made below by means of a comparative example and an example of the present invention.
Comparative example 1
This comparative example provides a method for rapid monitoring of polishing slurry stability, the method comprising the steps of:
selecting an N-type monocrystalline silicon wafer with the resistivity of 1.6 omega-cm as a conditioning piece, carrying out pre-cleaning, then carrying out double-side polishing on the conditioning piece by adopting a polishing solution, carrying out post-cleaning, and drying to obtain the polished silicon wafer. The process conditions of the pre-cleaning, the double-side polishing, the post-cleaning and the drying are the same as those of the embodiment 1, and are not described again.
And secondly, performing double-sided boron diffusion on the polished silicon wafer to obtain a boron diffusion silicon wafer with the sheet resistance of 40 omega and the uniformity of less than or equal to 3.
Thirdly, depositing silicon nitride antireflection films with the thickness of 60nm on the front and back surfaces of the boron diffusion silicon wafer respectively, wherein the refractive index is 2.2%, and sintering to obtain a monitoring wafer;
the sintering conditions were the same as in example 1 and are not described again.
And step four, carrying out a Sinton test on the monitoring sheet.
Comparative example 2
The comparative example provides a method for monitoring the stability of polishing solution, which comprises the steps of removing a cleaned wafer by back surface winding diffusion to serve as a monitoring wafer, and preparing the monitoring wafer through a back surface polishing process, back surface ultrathin oxide layer and polycrystalline silicon deposition, back surface phosphorus doping, front surface glass removal, front surface winding plating removal, aluminum oxide passivation, silicon nitride antireflection, screen printing of an electrode and sintering (the preparation of the monitoring wafer takes 420 min).
And (3) carrying out battery efficiency detection on the prepared monitoring sheet so as to verify the stability of the polishing solution.
In order to better illustrate the characteristics of the method for monitoring the stability of the polishing solution provided by the embodiment of the present invention, the following is a verification of the monitoring effect.
The original silicon wafers are strictly divided into 15 groups with numbers G1-G15. Wherein: G1/4/7/10/13A monitoring piece was prepared by the conventional method provided in comparative example 2; G2/5/8/11/14A monitoring piece was prepared using the method provided in example 1; G3/6/9/12/15A monitoring piece prepared using the method provided in comparative example 1.5 pieces of the monitoring tablets in each group are respectively numbered as G1-1/2/3/4/5, G2-1/2/3/4/5 to G15-1/2/3/4/5.
Carrying out a Sinton test on the battery pieces of the G2 group and the G3 group respectively in the first day, and carrying out battery efficiency detection on the battery pieces of the G1 group; and (3) carrying out a Sinton test on the battery pieces of the G5 and G6 groups on the next day, carrying out battery efficiency detection on the battery pieces of the G4 group, and repeating the steps until the fifth day, carrying out the Sinton test on the battery pieces of the G14 and G15 groups, and carrying out battery efficiency detection on the battery pieces of the G13 group. The results are shown below.
TABLE 1 Experimental results for Day1 (group G1)
TABLE 2 experiment results of Day1 (groups G2 and G3)
TABLE 3 Experimental results for Day2 (group G4)
TABLE 4 experiment results of Day2 (groups G5 and G6)
TABLE 5 Experimental results for Day3 (group G7)
TABLE 6 experiment results of Day3 (groups G8 and G9)
TABLE 7 Experimental results for Day4 (group G10)
TABLE 8 experiment results of Day4 (groups G11 and G12)
TABLE 9 Experimental results for Day5 (group G13)
Table 10Day5 results (groups G14 and G15)
The above J0 unit: fA/cm 2 (ii) a Minority carrier lifetime unit: μ s; ivoc units: and V.
The Uoc (open circuit voltage) unit: v; isc (short circuit current) unit: a; eta (cell efficiency) unit: percent; FF: fill factor, unit%.
By tracking the cell efficiency data detected within 5 days and the result of the Sinton test, it is found that there is an obvious correspondence between the cell efficiency data of the monitoring sheet prepared by the conventional method (comparative example 2) and the Sinton test result of the monitoring sheet provided by the present invention, such as minority carrier lifetime, J0, IVOC, i.e., the two sets of data are very matched, the stability of the polishing solution can be fully reflected, and the influence of the fluctuation or pollution of the chemical solution on the cell efficiency can be effectively controlled or avoided. Therefore, the monitoring sheet prepared by adopting 4 steps of double-sided polishing, double-sided phosphorus diffusion, silicon nitride antireflection, sintering and the like is adopted, and through the Sinton test, on the premise of simplifying the process steps, the test result is still accurate, whether the polishing solution is qualified, stable or not and whether the polishing solution is deteriorated or not can be fed back accurately, and the method has important significance for the industrial production of the N-type solar cell.
By adopting the method for rapidly monitoring the stability of the polishing solution provided by the invention, the same or corresponding technical effects in the embodiment 1 of the invention can be achieved as long as the process parameters of pre-cleaning, double-sided polishing, post-cleaning, double-sided phosphorus diffusion, silicon nitride antireflection film deposition and sintering of the test piece are adjusted within the preferable range of the invention.
By tracking the cell efficiency data of G1/4/7/10/13 and the Sinton test results of G3/6/9/12/15 within 5 days, it was demonstrated that even though the PN junction was present in the test piece prepared in comparative example 1, there was an antireflection film, but there was a large error in the test results due to the diffusion of boron employed.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. A method for rapidly monitoring the stability of polishing solution is characterized in that: the monitoring method comprises the following steps:
firstly, taking a P-type monocrystalline silicon wafer as a conditioning piece, carrying out pre-cleaning, then carrying out double-side polishing on the conditioning piece for 2-4 min at 50-55 ℃ by adopting a polishing solution, and then carrying out post-cleaning and drying to obtain a polished silicon wafer;
secondly, performing double-sided phosphorus diffusion on the polished silicon wafer to obtain a phosphorus diffusion silicon wafer;
depositing silicon nitride antireflection films on the front surface and the back surface of the phosphorus diffusion silicon wafer respectively, and sintering to obtain a monitoring piece;
and step four, carrying out a Sinton test on the monitoring sheet.
2. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: the resistivity of the P-type monocrystalline silicon wafer is 1.5-1.7 omega cm.
3. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: in the first step, the concentration of alkali in the polishing solution is 1.5wt% -2.0 wt%, and the alkali is KOH or NaOH; and/or
In the first step, the concentration of the additive in the polishing solution is 0.4wt% -0.6 wt%.
4. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: in the first step, the pre-cleaning comprises sequentially using a cleaning solution containing KOH and H 2 O 2 The aqueous solution is cleaned for 1min to 2min at the temperature of 50 ℃ to 55 ℃, and then is cleaned by deionized water, wherein the concentration of KOH in the aqueous solution is 1wt percent to 1.5wt percent; h in the aqueous solution 2 O 2 The concentration of (A) is 5wt% to 6wt%.
5. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: in the first step, the post-cleaning comprises cleaning for 1-2 min by sequentially adopting a mixed acid solution, and then performing slow pulling cleaning by adopting deionized water at the temperature of 10-30 ℃.
6. The method for rapidly monitoring the stability of a polishing solution according to claim 5, wherein: the mixed acid solution comprises HCl and HF, the concentration of the HCl in the mixed acid solution is 4wt% -4.5 wt%, and the solubility of the HF in the mixed acid solution is 2.5wt% -3 wt%; and/or
The specific process of slow pulling is as follows: and slowly lifting the debugging sheet out of the water surface, wherein the lifting time is 1-2 min.
7. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: in the first step, the drying conditions are as follows: the temperature is 70-80 ℃, and the time is 8-10 min; and/or
In the first step, the surface reflectivity of the polished silicon wafer is greater than 42%.
8. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: the sheet resistance of the phosphorus diffusion silicon chip is 35-40 omega, and the uniformity is less than or equal to 3; and/or
The specific process of the double-sided phosphorus diffusion comprises the following steps:
and (3) leak detection: the pressure is less than or equal to-200 pa;
and (3) heating: the temperature is 880-890 ℃, and the pressure is less than or equal to-10 pa;
pre-purification: the temperature is 880-895 ℃, and the time is 3-5 min;
deposition: the temperature is 880-890 ℃, and the time is 25-30 min;
propelling: the temperature is 890-905 ℃ and the time is 5-8 min;
post-purification: the temperature is 700-750 ℃, and the time is 1-2 min;
cooling: the temperature is 650-700 ℃, and the time is 20-30 min.
9. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: the thickness of the silicon nitride antireflection film is 55 nm-65 nm, and the refractive index is 2% -2.3%; and/or
The conditions for depositing the silicon nitride antireflection film are as follows:
NH 3 flow rate: the 1 st path is 400 +/-50 sccm, the 2 nd path and the 3 rd path are both 500 +/-50 sccm, and the 4 th, 5 th and 6 th paths are all 550 +/-50 sccm; siH 4 Flow rate: the 1 st path is 0, the 2 nd and 3 rd paths are all 300 plus or minus 50sccm, and the 4 th, 5 th and 6 th paths are all 200 plus or minus 50sccm; the microwave power of the heating chamber is 3000W-3600W, the temperature of the process chamber is 320-420 ℃, the pressure of the process chamber is 0.25 mbar-0.31 mbar, and the pulse switching ratio is 8/10.
10. The method for rapidly monitoring the stability of a polishing solution according to claim 1, wherein: the sintering conditions are as follows: the belt speed is as follows: 200ipm, zone1-Zone 10 temperature respectively 330 ℃, 360 ℃, 500 ℃, 550 ℃, 580 ℃, 630 ℃, 810 ℃ and 860 ℃; and/or test parameters of the Sinton test include minority carrier lifetime, reverse saturation current density, and open circuit voltage.
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