CN117637443A - Surface treatment method of silicon wafer - Google Patents
Surface treatment method of silicon wafer Download PDFInfo
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- CN117637443A CN117637443A CN202311717262.5A CN202311717262A CN117637443A CN 117637443 A CN117637443 A CN 117637443A CN 202311717262 A CN202311717262 A CN 202311717262A CN 117637443 A CN117637443 A CN 117637443A
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- silicon wafer
- cleaning
- gettering
- phosphorus
- alkaline
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 161
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 155
- 239000010703 silicon Substances 0.000 title claims abstract description 155
- 238000000034 method Methods 0.000 title claims abstract description 79
- 238000004381 surface treatment Methods 0.000 title claims abstract description 17
- 238000004140 cleaning Methods 0.000 claims abstract description 72
- 238000005247 gettering Methods 0.000 claims abstract description 58
- 230000008569 process Effects 0.000 claims abstract description 41
- 239000012535 impurity Substances 0.000 claims abstract description 34
- 239000012670 alkaline solution Substances 0.000 claims abstract description 25
- 239000012459 cleaning agent Substances 0.000 claims abstract description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 19
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 13
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 26
- 229910052698 phosphorus Inorganic materials 0.000 claims description 26
- 239000011574 phosphorus Substances 0.000 claims description 26
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 25
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 claims description 18
- 239000000243 solution Substances 0.000 claims description 18
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 14
- 239000000126 substance Substances 0.000 claims description 14
- 238000010438 heat treatment Methods 0.000 claims description 13
- CIWBSHSKHKDKBQ-JLAZNSOCSA-N Ascorbic acid Chemical compound OC[C@H](O)[C@H]1OC(=O)C(O)=C1O CIWBSHSKHKDKBQ-JLAZNSOCSA-N 0.000 claims description 10
- 239000012298 atmosphere Substances 0.000 claims description 9
- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 claims description 8
- 239000004094 surface-active agent Substances 0.000 claims description 8
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 claims description 8
- YWWDBCBWQNCYNR-UHFFFAOYSA-N trimethylphosphine Chemical compound CP(C)C YWWDBCBWQNCYNR-UHFFFAOYSA-N 0.000 claims description 8
- 229940051841 polyoxyethylene ether Drugs 0.000 claims description 7
- 229920000056 polyoxyethylene ether Polymers 0.000 claims description 7
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 7
- AEQDJSLRWYMAQI-UHFFFAOYSA-N 2,3,9,10-tetramethoxy-6,8,13,13a-tetrahydro-5H-isoquinolino[2,1-b]isoquinoline Chemical compound C1CN2CC(C(=C(OC)C=C3)OC)=C3CC2C2=C1C=C(OC)C(OC)=C2 AEQDJSLRWYMAQI-UHFFFAOYSA-N 0.000 claims description 6
- 239000004115 Sodium Silicate Substances 0.000 claims description 6
- 230000001681 protective effect Effects 0.000 claims description 6
- 239000000176 sodium gluconate Substances 0.000 claims description 6
- 235000012207 sodium gluconate Nutrition 0.000 claims description 6
- 229940005574 sodium gluconate Drugs 0.000 claims description 6
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 6
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 6
- 229960005070 ascorbic acid Drugs 0.000 claims description 5
- 235000010323 ascorbic acid Nutrition 0.000 claims description 5
- 239000011668 ascorbic acid Substances 0.000 claims description 5
- 235000019795 sodium metasilicate Nutrition 0.000 claims description 5
- 239000011248 coating agent Substances 0.000 claims description 4
- 238000000576 coating method Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 4
- 150000003017 phosphorus Chemical class 0.000 claims description 4
- RXJKFRMDXUJTEX-UHFFFAOYSA-N triethylphosphine Chemical compound CCP(CC)CC RXJKFRMDXUJTEX-UHFFFAOYSA-N 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 239000012299 nitrogen atmosphere Substances 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 19
- 238000004519 manufacturing process Methods 0.000 abstract description 13
- 238000005520 cutting process Methods 0.000 abstract description 6
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 4
- 239000002253 acid Substances 0.000 abstract description 2
- 235000012431 wafers Nutrition 0.000 description 121
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 24
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 10
- 238000005406 washing Methods 0.000 description 10
- 235000011121 sodium hydroxide Nutrition 0.000 description 8
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 6
- 125000004429 atom Chemical group 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000009792 diffusion process Methods 0.000 description 5
- 238000010521 absorption reaction Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000003647 oxidation Effects 0.000 description 4
- 238000007254 oxidation reaction Methods 0.000 description 4
- 238000005554 pickling Methods 0.000 description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000011863 silicon-based powder Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 239000002173 cutting fluid Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 239000002923 metal particle Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000000844 anti-bacterial effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000004945 emulsification Methods 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 230000009969 flowable effect Effects 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 229910001425 magnesium ion Inorganic materials 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 239000012466 permeate Substances 0.000 description 1
- 125000004437 phosphorous atom Chemical group 0.000 description 1
- 239000005360 phosphosilicate glass Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000007581 slurry coating method Methods 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 230000003381 solubilizing effect Effects 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 238000004659 sterilization and disinfection Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229920003169 water-soluble polymer Polymers 0.000 description 1
- 238000009736 wetting Methods 0.000 description 1
Classifications
-
- 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
Landscapes
- Cleaning Or Drying Semiconductors (AREA)
Abstract
The application relates to a surface treatment method of a silicon wafer, which comprises the following steps: cleaning the surface of the cut silicon wafer for the first time by using cleaning liquid to remove a dirty layer on the surface of the silicon wafer; performing second cleaning on the surface of the silicon wafer by using an alkaline solution to remove a damaged layer on the surface of the silicon wafer; thirdly, cleaning the surface of the silicon wafer by using pure water to remove impurities remained on the surface of the silicon wafer; drying the silicon wafer; and performing a gettering process on the surface of the silicon wafer. The step of cleaning by adding the cleaning agent is used for cleaning the dirt layer, so that alkaline insoluble impurities are prevented from appearing when the damaged layer is removed by subsequent alkaline cleaning, the subsequent cleaning process is required to be added with an acid cleaning process for removal, the treatment process is increased, the use cost of the reagent is increased, and the subsequent impurity absorbing effect is even influenced. The method and the device effectively solve the problem that in the prior art, dirty layers are easily generated in the cutting process of the silicon wafer, and the production efficiency of the silicon wafer before gettering is affected.
Description
Technical Field
The application relates to the technical field of silicon wafer processing, in particular to a surface treatment method of a silicon wafer.
Background
The manufacturing process of the silicon wafer can cause defects at a plurality of positions, part of the defects can be processed through the gettering process to meet the qualified requirement, the yield of the silicon wafer is increased, the cost is further reduced, the overall economy is improved, and meanwhile, the silicon wafer can also develop towards the flaking direction of the silicon wafer.
In the production link of the silicon wafer, because the silicon wafer may generate a dirty layer when being cut, the dirty layer comprises soluble or flowable cutting liquid silicon powder and the like, the existence of the dirty layer may have an obstructing effect on the subsequent gettering effect, while in the prior art, the silicon wafer after being cut is usually directly subjected to alkaline washing by using a strong alkaline solution, although part of impurities can be removed, part of insoluble products such as silicate and the like are also generated, so that the silicate is attached to the surface of the silicon wafer, the silicate needs to be further removed, the production efficiency before the silicon wafer gettering is affected, and even the effect of the subsequent gettering process is affected.
Disclosure of Invention
The application provides a surface treatment method of a silicon wafer, which aims to solve the problem that dirty layers are easily generated in the cutting process of the silicon wafer in the prior art, and the production efficiency of the silicon wafer before gettering is affected.
The application provides a surface treatment method of a silicon wafer, which comprises the following steps:
s10, cleaning the surface of the cut silicon wafer for the first time by using cleaning liquid to remove a dirty layer on the surface of the silicon wafer;
s20, performing second cleaning on the surface of the silicon wafer by using an alkaline solution to remove a damaged layer on the surface of the silicon wafer;
s30, cleaning the surface of the silicon wafer for the third time by using pure water to remove impurities remained on the surface of the silicon wafer;
s40, drying the silicon wafer;
s50, performing a gettering process on the surface of the silicon wafer.
According to some embodiments of the present application, the alkaline solution is a mixed solution comprising an alkaline substance and hydrogen peroxide.
According to some embodiments of the application, the concentration of hydrogen peroxide of the alkaline solution is 0.3% to 2%.
According to some embodiments of the present application, the cleaning liquid is a mixture of a first cleaning agent comprising a surfactant and a first builder and a second cleaning agent comprising an alkaline material and a second builder.
According to some embodiments of the present application, the surfactant includes polyoxyethylene ether, sodium carbonate, and diethylene glycol.
According to some embodiments of the present application, the first builder comprises ascorbic acid and the second builder comprises sodium gluconate and sodium metasilicate.
According to some embodiments of the present application, the first cleaning of the surface of the cut silicon wafer with the cleaning solution further comprises controlling the temperature of the cleaning environment between 45 ℃ and 55 ℃.
According to some embodiments of the present application, the drying the silicon wafer further comprises:
s41, heating clean air;
and S42, continuously leading the clean air to the surface of the silicon wafer.
According to some embodiments of the present application, the performing the gettering process of the surface of the silicon wafer further includes:
s51, coating a phosphorus source on the surface of the silicon wafer;
s52, introducing protective atmosphere into the heat treatment furnace;
s53, placing the silicon wafer into the heat treatment furnace to perform phosphorus gettering treatment.
According to some embodiments of the present application, the phosphorus source is one or more of phosphorus oxychloride, trimethylphosphorus, triethylphosphorus, phosphorus pentoxide, and diethylhydrogenated phosphorus, the protective atmosphere is a nitrogen atmosphere or an inert gas atmosphere, and the temperature of the heat treatment furnace is between 800 ℃ and 900 ℃.
Compared with the prior art, the technical scheme provided by the embodiment of the application has the following advantages:
the surface treatment method of the silicon wafer provided by the embodiment of the application comprises the following steps: cleaning the surface of the cut silicon wafer for the first time by using cleaning liquid to remove a dirty layer on the surface of the silicon wafer; performing second cleaning on the surface of the silicon wafer by using an alkaline solution to remove a damaged layer on the surface of the silicon wafer; thirdly, cleaning the surface of the silicon wafer by using pure water to remove impurities remained on the surface of the silicon wafer; drying the silicon wafer; and performing a gettering process on the surface of the silicon wafer. The step of cleaning by adding the cleaning agent is used for cleaning the dirt layer, so that alkaline insoluble impurities are prevented from appearing when the damaged layer is removed by subsequent alkaline cleaning, the subsequent cleaning process is required to be added with an acid cleaning process for removal, the treatment process is increased, the use cost of the reagent is increased, and the subsequent impurity absorbing effect is even influenced. The method and the device effectively solve the problem that in the prior art, dirty layers are easily generated in the cutting process of the silicon wafer, and the production efficiency of the silicon wafer before gettering is affected.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
One or more embodiments are illustrated by way of example and not limitation in the figures of the accompanying drawings, in which like references indicate similar elements, and in which the figures of the drawings are not to be taken in a limiting sense, unless otherwise indicated.
Fig. 1 is a schematic flow chart of a surface treatment method of a silicon wafer according to an embodiment of the present application;
FIG. 2 shows a schematic flow chart of a dried silicon wafer of the surface treatment method of the silicon wafer of FIG. 1;
fig. 3 shows a schematic flow chart of a gettering process of the surface treatment method of the silicon wafer of fig. 1.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
The following disclosure provides many different embodiments, or examples, for implementing different structures of the invention. In order to simplify the present disclosure, components and arrangements of specific examples are described below. They are, of course, merely examples and are not intended to limit the invention. Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.
For ease of description, spatially relative terms, such as "inner," "outer," "lower," "upper," "above," "front," "rear," and the like, may be used herein to describe one element's or feature's relative positional relationship or movement to another element's or feature as illustrated in the figures. Such spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figure experiences a position flip or a change in attitude or a change in state of motion, then the indications of these directivities correspondingly change, for example: an element described as "under" or "beneath" another element or feature would then be oriented "over" or "above" the other element or feature. Thus, the example term "below … …" may include both upper and lower orientations. The device may be otherwise oriented (rotated 90 degrees or in other directions) and the spatial relative relationship descriptors used herein interpreted accordingly.
As shown in fig. 1, an embodiment of the present application provides a surface treatment method for a silicon wafer, including the following steps:
s10, cleaning the surface of the cut silicon wafer for the first time by using cleaning liquid to remove a dirty layer on the surface of the silicon wafer; the first cleaning device can be used for treating residual cutting fluid, silicon powder, partial metal particles and the like on the surface of the silicon wafer, and can be used for effectively removing the residual cutting fluid, the silicon powder, the partial metal particles, the subsequent alkaline cleaning process and insoluble attachments are avoided, and the subsequent cleaning and gettering are inconvenient to remove and affected.
S20, performing second cleaning on the surface of the silicon wafer by using an alkaline solution to remove a damaged layer on the surface of the silicon wafer; when the cutting line moves reciprocally, the path of the silicon wafer may be deflected, so that the surface of the silicon wafer protrudes or is sunken to damage the layer, the damage layer has a serious blocking effect on the subsequent gettering effect, and the damage layer needs to be effectively removed by using alkaline solution. The pH value of the alkaline solution adopted in the specific embodiment is within the range of 10.5+/-0.5, so that the silicon wafer pollution caused by back diffusion in the subsequent high-temperature gettering process can be effectively prevented.
S30, cleaning the surface of the silicon wafer for the third time by using pure water to remove impurities remained on the surface of the silicon wafer; because the first cleaning uses the cleaning agent to effectively remove the dirt layer, the alkaline solution can clean the damage layer without generating insoluble impurities, and impurities on the surface can be taken away in the cleaning process, therefore, the surface of the silicon wafer after the second cleaning does not need to be subjected to the pickling process, the alkaline solution is diluted and flushed by pure water, and the final cleaning of the surface of the silicon wafer is finished, so that the pickling process can be saved, the cleaning efficiency is improved, the reagent investment and the time cost investment of pickling can be reduced, and the effects of reducing the cost and improving the efficiency are achieved.
S40, drying the silicon wafer; the method is used for surface drying of the silicon wafer and is convenient for subsequent procedures.
S50, performing a gettering process on the surface of the silicon wafer. Specifically, the silicon wafer is contacted with the gettering material and heated, so that atoms of the gettering material gradually permeate into the crystal lattice of the silicon wafer to form covalent bonds with the silicon atoms, thereby changing the conductivity of the silicon wafer.
According to the technical scheme, the step of cleaning by adding the cleaning agent is added to clean the dirt layer, so that alkaline insoluble impurities are prevented from appearing when the damaged layer is removed by subsequent alkaline cleaning, the subsequent cleaning process is required to be added for removing by the pickling process, the treatment process is increased, the use cost of the reagent is increased, and the subsequent impurity absorbing effect is even affected. The method and the device effectively solve the problem that in the prior art, dirty layers are easily generated in the cutting process of the silicon wafer, and the production efficiency of the silicon wafer before gettering is affected.
Further, in the technical solution of the present embodiment, the alkaline solution is a mixed solution containing an alkaline substance and hydrogen peroxide. The alkaline solution arranged in the way can not only be used for alkaline washing, but also enable the surface of the silicon wafer to have a hydrophilic interface, and concretely, hydrogen peroxide is often in the form of aqueous solution, commonly called hydrogen peroxide, which is slightly acidic and can be decomposed to a certain extent when mixed with the alkaline solution to generate nascent oxygen, so that a layer of hydrophilic film can be formed on the surface of the silicon wafer, the uniformity, the deposition rate and the coverage of the subsequent gettering process coating can be improved, the gettering effect can be improved, and further the quality of the silicon wafer can be improved better.
Compared with the traditional process that a hydrophilic film needs to be formed through an ozone oxidation mode after the silicon wafer is cleaned, in the embodiment, the ozone oxidation mode can be directly reduced, ozone needs to be prepared on site in the process, ultraviolet lamps are required to be irradiated, the oxidation efficiency of ozone is poor in controllability, meanwhile, a large amount of time is required to be consumed for ultraviolet lamp irradiation and ozone generation, the silicon wafer preparation efficiency is affected, and the overall production efficiency is further affected.
It should be noted that, since the alkaline solution has instability with the hydrogen peroxide solution, the alkaline solution needs to be prepared before the second washing, i.e., the alkaline washing, and the preparation process is as follows:
adding alkaline substances and pure water in a fixed proportion into a container to prepare alkaline liquid;
the hydrogen peroxide solution of a corresponding purity and volume is poured into the container to prepare the alkaline liquid for final use.
The alkaline substance in the alkaline liquid can be sodium hydroxide and/or potassium hydroxide, and sodium hydroxide is commonly used as the alkaline substance in the solution, so that the alkaline substance has the advantages of higher economy, easy acquisition, relatively lower cost and higher potassium hydroxide cost, but has higher solubility, and under the same conditions, the alkalinity of the saturated potassium hydroxide solution is stronger than that of the sodium hydroxide solution.
Further, in the technical solution of this embodiment, the concentration of hydrogen peroxide of the alkaline solution is 0.3% to 2%. Based on the surface of the silicon wafer cleaned by the cleaning solution, the alkaline solution with the concentration can form a stable and reliable hydrophilic film so as to facilitate the subsequent process.
In a specific embodiment, the alkaline substance is sodium hydroxide, diluted with liquid pure water, specifically, 138g to 142g of sodium hydroxide solid is dissolved in 600L of pure water, and 10L of hydrogen peroxide solution with the purity of 28% is added after the sodium hydroxide is completely dissolved, so that a mixed alkaline solution with the pH of about 11 and the hydrogen peroxide concentration of about 0.45% can be formed.
Because part of alkaline solution possibly remains on the surface of the silicon wafer in the alkaline washing process, the alkaline solution can be dissolved in water by washing the washed silicon wafer with pure water after the third washing, namely water washing, and the residual alkaline solution on the surface of the silicon wafer can be removed, and the impurity content on the surface of the silicon wafer can be reduced by washing the rest of impurities on the surface of the silicon wafer with water. Meanwhile, in the cleaning treatment before gettering, hydrogen peroxide is added in the alkaline cleaning process to treat the silicon wafer, so that the effect of oxidizing the surface of the silicon wafer can be achieved without adding additional ozone for oxidation, and the method is safe and environment-friendly; in addition, the hydrogen peroxide is added without adding equipment, so that the cost is low; thereby being beneficial to improving the gettering effect, improving the yield of products, improving the photoelectric conversion efficiency of the solar cell and having good application prospect.
It should be noted that, the temperature and time of the cleaning process can be regulated and controlled according to the actual production condition of the site, the temperature is mainly related to the model of the cleaning agent, and the cleaning time is set according to the specific cleaning temperature or other working procedure requirements. Therefore, through the multiple cleaning steps, the damaged layer and metal impurities on the surface of the silicon wafer such as the N-type silicon wafer and other impurities attached to the surface of the silicon wafer can be effectively removed; the surface of the silicon wafer can be smoother, and the subsequent operations such as texturing and the like are facilitated.
In the technical solution of this embodiment, the cleaning liquid is a mixture of a first cleaning agent and a second cleaning agent, the first cleaning agent includes a surfactant and a first builder, and the second cleaning agent includes an alkaline substance and a second builder. The alkaline substance can be arranged correspondingly to the cleaning capacity, and the cleaning effect of the cleaning liquid is improved through the addition of the first builder and the second builder. The surfactant has high-efficiency cleaning and sterilizing functions, and can effectively decompose and remove the dirty layer through a series of physical and chemical actions (such as wetting, penetrating, emulsifying, solubilizing, dispersing, foaming and the like) with dirt of the dirty layer and the solid surface. The mixing arrangement of a plurality of cleaning agents can effectively improve the cleaning of the silicon wafer.
Further, in the technical solution of this embodiment, the surfactant includes polyoxyethylene ether, sodium carbonate, and diethylene glycol. The polyoxyethylene ether, sodium carbonate and diethylene glycol are all soluble in water to perform good cleaning and disinfection functions, wherein the polyoxyethylene ether can dissolve a plurality of organic and inorganic substances. The solubility of the water-soluble polymer in water is high, so that stable aqueous solution can be formed; sodium carbonate has certain alkalinity, and can play a role in softening water quality, namely, calcium ions, magnesium ions and the like in water are replaced by sodium ions of the sodium carbonate, so that solid precipitate substances are not easy to form; diethylene glycol has high antibacterial property and can be used as a lubricant to effectively reduce friction and abrasion, thereby prolonging the service life of a lubrication system.
Still further, in the solution of the present embodiment, the first builder includes ascorbic acid, and the second builder includes sodium gluconate and sodium metasilicate. The arrangement of the ascorbic acid can quickly precipitate metal ions, prevent the reattachment of pollutants, keep the necessary alkalinity for washing, simultaneously disperse and suspend dirt and ash, and improve the performance of the surfactant. The polyoxyethylene ether can be blended to better dissolve organic and inorganic substances. The sodium gluconate can strengthen the cleaning effect, the sodium metasilicate is a low-molecular crystal prepared by the hydrothermal reaction of common sodium silicate and caustic soda, has strong emulsification on lubricating oil and fat, faces dirt in the production process of silicon wafers, and has good decomposition effect when being matched with the sodium gluconate.
Specifically, in the technical solution of the embodiment, a mixing ratio of the first cleaning agent and the second cleaning agent in the cleaning solution is 2:1, where the first cleaning agent includes: 8 to 10 parts of polyoxyethylene ether, 15 to 20 parts of sodium carbonate, 10 to 12 parts of diethylene glycol, 1 to 3 parts of ascorbic acid and 55 to 65 parts of deionized water, and the second cleaning agent comprises: 1 to 2 parts of potassium hydroxide, 15 to 20 parts of sodium hydroxide, 7 to 10 parts of sodium gluconate, 8 to 10 parts of sodium metasilicate and 55 to 65 parts of deionized water.
Further, in the technical scheme of the embodiment, the cleaning solution is used for cleaning the surface of the cut silicon wafer for the first time, and the method further comprises the step of controlling the temperature of the cleaning environment to be between 45 ℃ and 55 ℃. The first cleaning agent and the second cleaning agent in the embodiment have the optimal temperature of 50 ℃, and can play an optimal cleaning role so as to ensure that the subsequent working procedures are normally carried out.
As shown in fig. 2, in the technical solution of this embodiment, the drying silicon wafer further includes:
s41, heating clean air; specifically, clean air can be prepared by adding a heat source and a flow pipeline; including but not limited to, air collection by collection equipment and preliminary filtration of the air to produce clean air, reducing the likelihood of reaction with the silicon wafer and liquids on the silicon wafer.
And S42, continuously leading clean air to the surface of the silicon wafer. In this embodiment, through the mode of letting in the blowing carry out drying treatment, can improve the efficiency of drying like this, take away the air that has vapor, drying effect is better on the one hand, on the other hand can guarantee that the silicon chip can not receive the influence of foreign matter, even contain impurity in the air also can be taken away in the direction of directional blowing can not have accumulational possibility, the whole impurity degree of silicon chip is lower.
After the drying step is completed, in the technical scheme of the embodiment, a sorting machine can be used for detecting the silicon wafer, the minority carrier lifetime defect occurs in the silicon wafer, and the gettering process is needed for processing. So as to improve the overall qualification rate of the silicon wafer and further avoid the generation of waste products.
Further, the gettering process of the surface of the silicon wafer in this embodiment is not limited to a specific type of silicon wafer, for example, the silicon wafer may be an N-type silicon wafer or a P-type silicon wafer. The N-type silicon wafer is used as the substrate to prepare the solar cell, such as an N-type heterojunction solar cell, so that the manufacturing cost of the N-type heterojunction solar cell can be reduced. For brevity, the silicon wafer gettering method of the present invention will be described in detail mainly using an N-type silicon wafer as an example, however, it should be understood that the same or similar principle is adopted when a P-type silicon wafer is used, and will not be described herein. It can be understood that in the gettering treatment of the silicon wafer, a relatively common method adopts processes such as phosphorus gettering and aluminum gettering to remove impurities such as transition metals in the silicon wafer. The phosphorus gettering utilizes the structural difference between impurity atoms and silicon atoms, and diffuses the impurity atoms to the surface of the silicon wafer to cause misfit dislocation, so that a stress gettering center is formed; the phosphorus gettering method is simple and the process period is short. For brevity, the silicon wafer gettering method of the present invention is mainly described below by taking gettering as phosphorus gettering as an example, and the use condition of the gettering process in a specific section is mainly described.
Specifically, as shown in fig. 3, in the technical solution of this embodiment, the process for performing gettering on the surface of the silicon wafer further includes:
s51, coating a phosphorus source on the surface of the silicon wafer; that is, the technical scheme of the embodiment adopts a phosphorus gettering mode to carry out gettering treatment, and the structural difference of impurity atoms and silicon atoms is utilized to diffuse the impurity atoms to the surface of a silicon wafer to cause mismatching dislocation, so that a stress gettering center is formed; the phosphorus gettering method is simple and the process period is short.
S52, introducing protective atmosphere into the heat treatment furnace; to avoid other gases in the air from affecting the process of phosphorus gettering.
S53, placing the silicon wafer into a heat treatment furnace for phosphorus gettering treatment. In particular, it may be a diffusion furnace, commonly used in the art of manufacturing processes.
Further, in the technical scheme of the embodiment, the phosphorus source is one or more of phosphorus oxychloride, trimethylphosphorus, triethylphosphorus, phosphorus pentoxide and diethylhydrogenated phosphorus, the protective atmosphere is nitrogen atmosphere or inert gas atmosphere, and the temperature of the heat treatment furnace is between 800 ℃ and 900 ℃. The phosphorus source is one or more of phosphorus oxychloride, trimethylphosphorus, triethylphosphorus, phosphorus pentoxide and diethylhydrogenated phosphorus, so that the phosphorus source is convenient to obtain, the production efficiency can be improved, and the cost can be reduced. The temperature of the heat treatment furnace is between 800 ℃ and 900 ℃, and the high-temperature phosphorus gettering of the silicon wafer can be realized by carrying out phosphorus diffusion at high temperature, so that the gettering effect is good, and the conversion efficiency of the solar cell is improved.
In the step of phosphorus gettering treatment, the higher the phosphorus concentration is, the higher the impurity segregation coefficient is, the more favorable for gettering is, the lower the temperature is, the higher the segregation coefficient is, the more favorable for gettering is, so that the effect of high-temperature phosphorus gettering is better by limiting the treatment or diffusion time, the gettering effect is favorable to be ensured, and the conversion efficiency of the solar cell is improved.
Through the phosphorus gettering treatment, a layer of phosphorus doped phosphosilicate glass layer is formed on the upper surface and the lower surface of the silicon wafer as a gettering layer by utilizing the gettering principle that phosphorus slurry diffuses into the silicon wafer under the high-temperature condition, and metal impurities (such as Fe, na, K and the like) are bound in a preset area, so that the concentration of the metal impurities in a device working area is reduced, and the doping concentration of an interface can be reduced. It can be understood that the more phosphorus atoms are doped into the silicon wafer, the wider the diffusion depth is, the smaller the sheet resistance is, and the better the gettering effect is relatively.
In summary, the technical scheme of the application includes: the method has the advantages that the method is used for cleaning the silicon wafer before the impurity absorption, can be used for removing the impurity on the surface of the silicon wafer by the pre-cleaning treatment of the silicon wafer, improves the cleanliness of the surface of the silicon wafer before the impurity absorption, is beneficial to the operation of the impurity absorption process, and improves the uniformity, the deposition rate and the like of slurry coating in the impurity absorption process. The silicon wafer after the front cleaning is subjected to gettering treatment, and the metal impurities in the silicon wafer can be removed by the gettering treatment, so that the quality of the silicon wafer is improved, and the conversion efficiency of a battery is improved.
It is to be understood that the terminology used herein is for the purpose of describing particular example embodiments only, and is not intended to be limiting. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms "comprises," "comprising," "includes," "including," and "having" are inclusive and therefore specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order described or illustrated, unless an order of performance is explicitly stated. It should also be appreciated that additional or alternative steps may be used.
Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as "first," "second," and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments.
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. The surface treatment method of the silicon wafer is characterized by comprising the following steps:
s10, cleaning the surface of the cut silicon wafer for the first time by using cleaning liquid to remove a dirty layer on the surface of the silicon wafer;
s20, performing second cleaning on the surface of the silicon wafer by using an alkaline solution to remove a damaged layer on the surface of the silicon wafer;
s30, cleaning the surface of the silicon wafer for the third time by using pure water to remove impurities remained on the surface of the silicon wafer;
s40, drying the silicon wafer;
s50, performing a gettering process on the surface of the silicon wafer.
2. The method for surface treatment of a silicon wafer according to claim 1, wherein the alkaline solution is a mixed solution containing an alkaline substance and hydrogen peroxide.
3. The method for surface treatment of a silicon wafer according to claim 2, wherein the concentration of hydrogen peroxide of the alkaline solution is 0.3% to 2%.
4. The method of claim 1, wherein the cleaning liquid is a mixture of a first cleaning agent and a second cleaning agent, the first cleaning agent comprising a surfactant and a first builder, the second cleaning agent comprising an alkaline material and a second builder.
5. The method of surface treatment of silicon wafer according to claim 4, wherein the surfactant comprises polyoxyethylene ether, sodium carbonate and diethylene glycol.
6. The method of claim 5, wherein the first builder comprises ascorbic acid and the second builder comprises sodium gluconate and sodium metasilicate.
7. The method of claim 6, wherein the first cleaning of the surface of the cut silicon wafer with the cleaning solution further comprises controlling the temperature of the cleaning environment to be between 45 ℃ and 55 ℃.
8. The method of surface treatment of a silicon wafer according to claim 1, wherein the drying the silicon wafer further comprises:
s41, heating clean air;
s42 continues to direct the clean air to the surface of the silicon wafer.
9. The method of claim 1, wherein the performing a gettering process of the surface of the silicon wafer further comprises:
s51, coating a phosphorus source on the surface of the silicon wafer;
s52, introducing protective atmosphere into the heat treatment furnace;
s53, placing the silicon wafer into the heat treatment furnace for phosphorus gettering treatment.
10. The method for surface treatment of silicon wafer according to claim 9, wherein the phosphorus source is one or more of phosphorus oxychloride, trimethylphosphorus, triethylphosphorus, phosphorus pentoxide and diethylhydrogenated phosphorus, the protective atmosphere is a nitrogen atmosphere or an inert gas atmosphere, and the temperature of the heat treatment furnace is 800 ℃ to 900 ℃.
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