Silicon wafer cleaning process
By combining electrochemical treatment with multiple cleaning solutions, the problem of residual organic matter and metal ions in silicon wafer cleaning was solved, improving the cleanliness and smoothness of the silicon wafer surface and avoiding the shortcomings of traditional methods.
Patent Information
- Application Number
- CN202410676001.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-28
- Publication Date
- 2025-11-28
AI Technical Summary
Existing technologies are ineffective at removing organic matter and metal ions during silicon wafer cleaning, resulting in residual contaminants on the silicon wafer surface. Furthermore, traditional methods may lead to increased surface roughness and damage to the silicon wafer.
An electrochemical treatment containing concentrated H2SO4 and H2O2 is employed. This electrochemical treatment combines a cleaning solution of O3, NH4OH, and H2O, with the silicon wafer used as the anode for electrochemical treatment. The cleaning solution of concentrated H2SO4 and H2O2, HCl, and HF is used to gradually remove contaminants from the surface of the silicon wafer.
It effectively removes organic matter and metal ions from the surface of silicon wafers, maintains the smoothness of the silicon wafer surface, improves the quality of silicon wafers, and reduces breakage.
Smart Images
Figure CN121034945A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of semiconductor technology, in particular to a silicon wafer cleaning process. BACKGROUND
[0002] With the large-scale development of integrated circuits, the number of transistors integrated on a semiconductor chip will double every year, thereby bringing requirements for device size reduction, circuit area reduction, and integration improvement, and further requirements for the particles and metal ions remaining on the surface of the silicon wafer are becoming higher and higher. At present, in the growth process of the silicon wafer, the types and contents of pollutants contacted in the processes such as crystal pulling, slicing, and lapping are more, and after the polishing process, the surface of the silicon wafer contains more polishing liquid, organic particles (mainly wax, mainly composed of rosin), and metal ions and other residues, therefore, the cleaning treatment of the silicon wafer after polishing is particularly important.
[0003] The prior art usually adopts a wet chemical method to clean the silicon wafer, and the conventional wet chemical method adopts an RCA cleaning process, and the commonly used cleaning liquid is mainly SC-1, SC-2, and DHF, wherein SC-1 is composed of H2O2, NH4OH, and H2O, SC-2 is composed of H2O2, HCl, and H2O, and DHF is composed of HF and H2O. In the conventional RCA cleaning process, the removal of the organic matter still mainly depends on NH4OH in SC-1 to corrode the surface of the silicon wafer, so that the adhered particles are loosened, and then the surface particles of the silicon wafer are further removed by using the ultrasonic cavitation principle, but when cleaning the silicon wafer after the wax-containing polishing process, due to the fact that a large amount of organic matter is adhered to the back surface of the silicon wafer, under the condition of the load effect of the added layer, the residual organic particles after the conventional RCA cleaning are still more; and the temperature of the conventional RCA cleaning process is high, and the concentration of the cleaning liquid is large, thereby causing the surface roughness of the silicon wafer to increase and the surface quality of the silicon wafer to decrease; in addition, in order to improve the cleaning effect, the prior art usually matches a high-power ultrasonic treatment, thereby causing the silicon wafer to be damaged.
[0004] Therefore, it is urgent to provide a cleaning process which can take into account the cleaning effect of the silicon wafer and the quality of the silicon wafer. SUMMARY
[0005] Based on this, it is necessary to provide a silicon wafer cleaning process which can efficiently remove the pollutants on the surface of the silicon wafer while maintaining the smoothness of the surface of the silicon wafer, effectively improve the quality of the silicon wafer, and have a wide application prospect.
[0006] The present application provides a silicon wafer cleaning process, which comprises the following steps:
[0007] The first cleaning liquid is used to perform a first cleaning treatment on the silicon wafer, and the first cleaning liquid remaining on the surface of the silicon wafer is removed, and the first cleaning liquid comprises concentrated H2SO4 and H2O2;
[0008] electrolyte, wherein the first electrolyte comprises O3, NH4OH and H2O;
[0009] second electrolyte, wherein the second electrolyte comprises O3, NH4OH and H2O;
[0010] second cleaning liquid, wherein the second cleaning liquid comprises concentrated H2O2, HCl and H2O;
[0011] third cleaning liquid, wherein the third cleaning liquid comprises HF and H2O.
[0012] In one embodiment, the first electrochemical treatment process satisfies at least one of the following conditions:
[0013] (1) the volume ratio of O3, NH4OH and H2O in the first electrolyte is 1:1:10-24.7:1:50;
[0014] (2) the time of the first electrochemical treatment is 10-15 min;
[0015] (3) the temperature of the first electrochemical treatment is 20-25℃;
[0016] (4) the current density of the first electrochemical treatment is 0.1A / cm 2 -0.8A / cm 2 ;
[0017] (5) the cathode material of the first electrochemical treatment is selected from iridium titanium mesh, platinum titanium mesh or iridium oxide coated titanium mesh.
[0018] In one embodiment, the second electrochemical treatment process satisfies at least one of the following conditions:
[0019] (1) the volume ratio of O3, NH4OH and H2O in the second electrolyte is 1:1:10-24.7:1:50;
[0020] (2) the time of the second electrochemical treatment is 10-15 min;
[0021] (3) the temperature of the second electrochemical treatment is 20-25℃;
[0022] (4) the current density of the second electrochemical treatment is 0.1A / cm2 ~0.8A / cm 2 ;
[0023] (5) The cathode material for the second electrochemical treatment is selected from iridium-titanium mesh, platinum-titanium mesh or iridium oxide-coated titanium mesh.
[0024] In one embodiment, the temperature of the first cleaning process is 115°C to 125°C, and the cleaning time is 5 min to 10 min.
[0025] In one embodiment, the volume ratio of concentrated H2SO4 to H2O2 in the first cleaning solution is 2:1 to 4:1.
[0026] In one embodiment, the temperature of the second cleaning process is 20°C to 25°C, and the cleaning time is 5 min to 10 min.
[0027] In one embodiment, the volume ratio of concentrated H2O2, HCl and H2O in the second cleaning solution is 1:1:30 to 1:1:50.
[0028] In one embodiment, the temperature of the third cleaning process is 20°C to 25°C, and the cleaning time is 1 min to 2 min.
[0029] In one embodiment, the volume ratio of HF to H2O in the third cleaning solution is 1:20 to 1:50.
[0030] In one embodiment, in the step of removing the first cleaning solution remaining on the silicon wafer surface, a deionized water rapid rinsing method is used, with a rinsing temperature of 55°C to 65°C and a rinsing time of 5 min to 10 min.
[0031] In one embodiment, in the steps of removing the first electrolyte residue on the silicon wafer surface, removing the second electrolyte residue on the silicon wafer surface, and removing the second cleaning solution residue on the silicon wafer surface, deionized water is used to quickly rinse the silicon wafer, and the rinsing temperature is independently selected from 20°C to 25°C, and the rinsing time is independently selected from 5 min to 10 min.
[0032] In one embodiment, in the step of cleaning the third cleaning solution remaining on the silicon wafer surface, a deionized water overflow rinsing method is used, with a rinsing temperature of 20°C to 25°C and a rinsing time of 5 min to 10 min.
[0033] In one embodiment, prior to the first cleaning process, the silicon wafer is overflow rinsed with deionized water at a temperature of 20°C to 25°C for 5 to 10 minutes.
[0034] The aforementioned silicon wafer cleaning process uses a mixed cleaning solution of O3, NH4OH, and H2O combined with electrochemical treatment, with the silicon wafer as the anode. First, due to water electrolysis, O2 is generated on the anode surface. Oxygen molecules, being small in diameter, accumulate in the gaps between contaminant particles and the silicon wafer surface. These gaps expand due to oxygen accumulation, and the overflowing oxygen impacts the contaminant particles on the silicon wafer surface. These two combined effects promote the self-detachment of contaminant particles and reduce silicon wafer breakage. Second, the O2 generated at the anode can work with O3 to oxidize the silicon wafer into silicon dioxide, while NH4OH can corrode the silicon dioxide on the wafer surface, thus assisting in the removal of contaminant particles. Simultaneously, NH4OH avoids direct corrosion of the silicon wafer, effectively maintaining the smoothness of the silicon wafer surface and improving wafer quality. Third, the metallic elements on the silicon wafer surface are converted into metal ions under electrochemical action and can undergo coordination reactions with NH4OH to form highly soluble complexes, thereby effectively improving the removal efficiency of metallic elements and metal ions from the silicon wafer surface.
[0035] Therefore, the silicon wafer cleaning process described in this invention effectively removes organic matter and metal ions from the surface of silicon wafers by using specific cleaning solutions and cleaning procedures, thereby improving the surface cleanliness of silicon wafers and having broad application prospects. Attached Figure Description
[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0037] Figure 1 This is a flowchart of the cleaning process in Embodiment 1 of the present invention. Detailed Implementation
[0038] To facilitate understanding of the present invention, it will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. Rather, these embodiments or examples are provided to make the disclosure of the present invention more thorough and complete.
[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments or examples only and is not intended to limit the invention. The optional scope of the term "and / or" as used herein includes any one of two or more of the related listed items, as well as any and all combinations of the related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.
[0040] The silicon wafer cleaning process provided by this invention includes the following steps:
[0041] S1. The silicon wafer is first cleaned with a first cleaning solution to remove the residual first cleaning solution on the surface of the silicon wafer. The first cleaning solution includes concentrated H2SO4 and H2O2.
[0042] S2. The silicon wafer is used as the anode for the first electrochemical treatment, and the first electrolyte remaining on the surface of the silicon wafer is removed, wherein the first electrolyte includes O3, NH4OH and H2O;
[0043] S3. The silicon wafer is used as the anode for a second electrochemical treatment to remove the second electrolyte remaining on the surface of the silicon wafer, wherein the second electrolyte includes O3, NH4OH and H2O;
[0044] S4. The silicon wafer is cleaned a second time using a second cleaning solution to remove any residual second cleaning solution from the surface of the silicon wafer. The second cleaning solution includes concentrated H2O2, HCl and H2O.
[0045] S5. The silicon wafer is cleaned a third time using a third cleaning solution to remove any residual third cleaning solution from the surface of the silicon wafer. The third cleaning solution includes HF and H2O.
[0046] It should be noted that the present invention does not impose any special limitations on the volume of the first cleaning solution, the second cleaning solution, the third cleaning solution, the first electrolyte, and the second electrolyte, and those skilled in the art can add them according to actual needs.
[0047] In one embodiment, before step S1, the silicon wafer is overflow rinsed with deionized water at a temperature of 20°C to 25°C for 5 to 10 minutes. This helps to remove particles and liquids with low adhesion to the silicon wafer surface and further improves the cleaning effect of the silicon wafer.
[0048] In step S1, concentrated H2SO4 and H2O2 have strong oxidizing properties, while concentrated H2SO4 has dehydrating properties. It can carbonize the organic matter on the silicon wafer surface and then further oxidize it into carbon oxides, thereby effectively removing organic particles. It is especially suitable for removing photoresist and other materials. In addition, it can oxidize some metal elements to generate metal ions.
[0049] In one embodiment, the volume ratio of concentrated H2SO4 to H2O2 in the first cleaning solution is 2:1 to 4:1.
[0050] It should be noted that the present invention does not have a special limitation on the concentration of concentrated H2SO4, as long as it is greater than or equal to 70%, for example, commercially available concentrated sulfuric acid with a concentration of 98% can be used.
[0051] In one embodiment, the temperature of the first cleaning process is 115°C to 125°C, and the cleaning time is 5 min to 10 min.
[0052] In one embodiment, in the step of removing the first cleaning solution remaining on the silicon wafer surface, a deionized water rapid rinsing method is used, with a rinsing temperature of 55°C to 65°C and a rinsing time of 5 min to 10 min. This effectively removes the first electrolyte while removing a large amount of organic matter and metal particles, thus avoiding contamination of the next process.
[0053] In steps S2 and S3, a mixed cleaning solution of O3, NH4OH, and H2O is used in conjunction with electrochemical treatment, with the silicon wafer as the anode. First, due to water electrolysis, O2 is generated on the anode surface. Oxygen molecules have a small diameter and accumulate in the gap between contaminant particles and the silicon wafer surface. The gap expands due to oxygen accumulation, and the overflowing oxygen has an impact effect on the contaminant particles on the silicon wafer surface. Under the synergistic effect of these two actions, the contaminant particles are promoted to detach, reducing silicon wafer breakage. Second, the O2 generated at the anode can work with O3 to oxidize the silicon wafer to form silicon dioxide, and NH4OH can corrode the silicon dioxide on the silicon wafer surface, thereby assisting in the removal of contaminant particles from the silicon wafer surface. At the same time, NH4OH avoids direct corrosion of the silicon wafer, effectively maintaining the smoothness of the silicon wafer surface and improving the quality of the silicon wafer. Third, the elemental metals on the silicon wafer surface are converted into metal ions under electrochemical action, and can undergo coordination reactions with NH4OH to form highly soluble complexes, thereby effectively improving the removal effect of elemental metals and metal ions on the silicon wafer surface.
[0054] Understandably, the present invention does not have any particular limitation on the aforementioned metal ions, and may use Ag. + Cu 2+ Ni 2+ Cd 2+ Zn 2 + Ca 2+Cr 2+ wait.
[0055] In one embodiment, the volume ratio of O3, NH4OH and H2O in the first electrolyte is 1:1:10 to 24.7:1:50, which is beneficial to promote the oxidation of silicon wafers to generate silicon dioxide, while ensuring the corrosion rate of the silicon wafer surface, maintaining the smoothness of the silicon wafer surface, and forming highly soluble complexes with metal ions, thereby further improving the particle removal effect on the silicon wafer surface.
[0056] In one embodiment, the duration of the first electrochemical treatment is 10 min to 15 min.
[0057] In one embodiment, the temperature of the first electrochemical treatment is 20°C to 25°C, thereby improving the solubility of O3 and preventing the corrosion rate of NH4OH on the silicon wafer from being too fast, thus maintaining the smoothness of the silicon wafer surface.
[0058] In one embodiment, the current density of the first electrochemical treatment is 0.1 A / cm². 2 ~0.8A / cm 2 .
[0059] In one embodiment, the cathode material for the first electrochemical treatment is selected from iridium-titanium mesh, platinum-titanium mesh, or iridium oxide-coated titanium mesh.
[0060] In one embodiment, in the step of removing the first electrolyte residue on the surface of the silicon wafer, the silicon wafer is rapidly rinsed with deionized water at 20°C to 25°C for 5 to 10 minutes, which effectively removes a large number of particles and metal ions while removing the first electrolyte.
[0061] In one embodiment, the volume ratio of O3, NH4OH and H2O in the second electrolyte is 1:1:10 to 24.7:1:50.
[0062] In one embodiment, the second electrochemical treatment lasts for 10 to 15 minutes.
[0063] In one embodiment, the temperature of the second electrochemical treatment is 20°C to 25°C.
[0064] In one embodiment, the current density of the second electrochemical treatment is 0.1 A / cm². 2 ~0.8A / cm 2 .
[0065] In one embodiment, the cathode material for the second electrochemical treatment is selected from iridium-titanium mesh, platinum-titanium mesh, or iridium oxide-coated titanium mesh.
[0066] In one embodiment, in the step of removing the second electrolyte residue on the surface of the silicon wafer, the silicon wafer is rapidly rinsed with deionized water at 20°C to 25°C for 5 to 10 minutes, which effectively removes a large number of particles and metal ions while removing the second electrolyte.
[0067] It should be noted that the present invention further improves the cleaning effect of silicon wafers through two electrochemical treatments, and the electrolyte ratio, temperature, time, current density, etc. of the first and second electrochemical treatments can be the same or different; the above electrochemical treatments use iridium-plated titanium metal, platinum-plated titanium metal, or titanium metal with iridium oxide coating as the anode interface.
[0068] In step S4, concentrated H2O2 and HCl can effectively remove a large number of metal ions, including but not limited to Al. 3+ Fe 3+ Mg 2+ Zn 2+ Na + .
[0069] It should be noted that the present invention does not impose any special restrictions on the concentration of the concentrated H2O2, as long as it is greater than or equal to 30%, for example, commercially available concentrated H2O2 with a concentration of 30% can be used.
[0070] In one embodiment, the volume ratio of concentrated H2O2, HCl and H2O in the second cleaning solution is 1:1:30 to 1:1:50.
[0071] In one embodiment, the temperature of the second cleaning process is 20°C to 25°C, and the cleaning time is 5 min to 10 min.
[0072] In one embodiment, in the step of removing the second cleaning liquid residue on the silicon wafer surface, the silicon wafer is rapidly rinsed with deionized water at 20°C to 25°C for 5 to 10 minutes, which effectively removes a large number of particles and metal ions while removing the second cleaning liquid.
[0073] In step S5, HF effectively removes metal and SiO2 from the surface of the silicon wafer.
[0074] In one embodiment, the volume ratio of HF to H2O in the third cleaning solution is 1:20 to 1:50.
[0075] In one embodiment, the temperature of the third cleaning process is 20°C to 25°C, and the cleaning time is 1 min to 2 min.
[0076] In one embodiment, in the step of removing the residual third cleaning fluid on the silicon wafer surface, a deionized water overflow rinsing method is used, with a rinsing temperature of 20°C to 25°C and a rinsing time of 5 min to 10 min, thereby effectively removing the third cleaning fluid and particles.
[0077] Specifically, the silicon wafer obtained in step S5 is dried to complete the silicon wafer cleaning process. It is understood that the present invention does not have any special limitations on the above drying method, and natural drying or baking methods can be used.
[0078] The silicon wafer cleaning process will be further described below through specific embodiments.
[0079] Example 1
[0080] S1. Rinse the silicon wafer with deionized water for 10 minutes. Then, clean the silicon wafer with the first cleaning solution at 115°C for 5 minutes. The volume ratio of concentrated H2SO4 to H2O2 in the first cleaning solution is 3:1. After completion, rinse the silicon wafer with deionized water at 65°C for 5 minutes.
[0081] S2. Using the silicon wafer obtained in step S1 as the anode, the anode interface material is iridium-plated titanium metal, and the cathode is an iridium-plated titanium mesh. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 24:1:50, at 0.8 A / cm². 2 Electrolyze at current density and 25°C for 10 minutes, then rinse the silicon wafer with deionized water at 25°C for 5 minutes.
[0082] S3. Using the silicon wafer obtained in step S2 as the anode, the anode interface material is iridium-plated titanium metal, and the cathode is an iridium-plated titanium mesh. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 24:1:50, at 0.8 A / cm². 2 Electrolyze at current density and 25°C for 15 minutes, then rinse the silicon wafer with deionized water for 5 minutes after completion.
[0083] S4. The silicon wafer obtained in step S3 is subjected to a second cleaning treatment at 25°C for 10 minutes. The volume ratio of concentrated H2O2, HCl and H2O in the second cleaning solution is 1:1:50. After completion, the silicon wafer is rinsed with deionized water at 25°C for 5 minutes.
[0084] S5. The silicon wafer obtained in step S4 is subjected to a third cleaning treatment at 25°C for 2 minutes. The volume ratio of HF to H2O in the third cleaning solution is 1:20. After completion, the silicon wafer is rinsed with deionized water at 25°C for 10 minutes.
[0085] Example 2
[0086] S1. Rinse the silicon wafer with deionized water for 5 minutes. Then, clean the silicon wafer with the first cleaning solution at 125°C for 10 minutes. The volume ratio of concentrated H2SO4 to H2O2 in the first cleaning solution is 2:1. After that, rinse the silicon wafer with deionized water at 70°C for 5 minutes.
[0087] S2. Using the silicon wafer obtained in step S1 as the anode, the anode interface material is iridium-plated titanium metal, and the cathode is an iridium-plated titanium mesh. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 10:1:60, at 0.15 A / cm². 2 Electrolyze at current density and 20℃ for 15 minutes, then rinse the silicon wafer with deionized water at 25℃ for 5 minutes.
[0088] S3. Using the silicon wafer obtained in step S2 as the anode, the anode interface material is iridium-plated titanium metal, and the cathode is an iridium-plated titanium mesh. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 10:1:60, at 0.15 A / cm². 2 Electrolyze at current density and 25°C for 10 minutes, then rinse the silicon wafer with deionized water for 10 minutes.
[0089] S4. The silicon wafer obtained in step S3 is subjected to a second cleaning treatment at 25°C for 12 minutes. The volume ratio of concentrated H2O2, HCl and H2O in the second cleaning solution is 1:1:30. After completion, the silicon wafer is rinsed with deionized water at 25°C for 10 minutes.
[0090] S5. The silicon wafer obtained in step S4 is subjected to a third cleaning treatment at 25°C for 1 minute. The volume ratio of HF to H2O in the third cleaning solution is 1:60. After completion, the silicon wafer is rinsed with deionized water at 25°C for 5 minutes.
[0091] Example 3
[0092] S1. Rinse the silicon wafer with deionized water for 5 minutes. Then, clean the silicon wafer with the first cleaning solution at 110°C for 12 minutes. The volume ratio of concentrated H2SO4 to H2O2 in the first cleaning solution is 4:1. After that, rinse the silicon wafer with deionized water at 55°C for 10 minutes.
[0093] S2. The silicon wafer obtained in step S1 is used as the anode. The anode interface material is iridium-plated titanium metal, and the cathode is an iridium-plated titanium mesh. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 24:1:50, at 0.8 A / cm². 2Electrolysis was performed at a current density of 25°C for 16 minutes, followed by rapid rinsing of the silicon wafer with deionized water at 25°C for 10 minutes.
[0094] S3. Using the silicon wafer obtained in step S2 as the anode, the anode interface material is a platinum-iridium alloy, and the cathode is a titanium-iridium alloy. The volume ratio of O3, NH4OH, and H2O in the electrolyte is 24:1:50, at 0.8 A / cm². 2 Electrolysis was performed at a current density of 25°C for 15 minutes, followed by rapid rinsing of the silicon wafer with deionized water for 10 minutes.
[0095] S4. The silicon wafer obtained in step S3 is subjected to a second cleaning treatment at 25°C for 12 minutes. The volume ratio of concentrated H2O2, HCl and H2O in the second cleaning solution is 1:1:40. After completion, the silicon wafer is rinsed with deionized water at 25°C for 10 minutes.
[0096] S5. The silicon wafer obtained in step S4 is subjected to a third cleaning treatment at 25°C for 3 minutes. The volume ratio of HF to H2O in the third cleaning solution is 1:20. After completion, the silicon wafer is rinsed with deionized water at 25°C for 10 minutes.
[0097] Comparative Example 1
[0098] The difference between Comparative Example 1 and Example 1 is that, in step S2, the silicon wafer obtained in step S1 is subjected to a second cleaning treatment at 25°C for 10 minutes, and the volume ratio of O3, NH4OH and H2O in the second cleaning solution is 24:1:50. After completion, the silicon wafer is rinsed with deionized water at 25°C for 5 minutes.
[0099] S3. The silicon wafer obtained in step S2 is subjected to a third cleaning treatment at 25°C for 10 minutes. The volume ratio of O3, NH4OH and H2O in the third cleaning solution is 24:1:50. After completion, the silicon wafer is rinsed with deionized water at 25°C for 5 minutes.
[0100] Comparative Example 2
[0101] The difference between Comparative Example 2 and Example 1 is that, in step S2, the silicon wafer obtained in step S1 is used as the anode, the anode interface material is iridium-plated titanium metal, the cathode is an iridium-plated titanium mesh, and the volume ratio of H2O2, NH4OH, and H2O in the electrolyte is 1:1:50, at 0.8 A / cm 2 Electrolyze at current density and 25°C for 10 minutes, then rinse the silicon wafer with deionized water at 25°C for 5 minutes.
[0102] S3. The silicon wafer obtained in step S2 is subjected to a second electrochemical treatment under the same conditions as in step S2. After the treatment is completed, the silicon wafer is rinsed with deionized water for 5 minutes.
[0103] Comparative Example 3
[0104] The difference between Comparative Example 3 and Example 1 is that only one electrochemical treatment was performed. After the first electrochemical treatment was completed and the silicon wafer was quickly rinsed with deionized water, a second cleaning treatment was performed.
[0105] Comparative Example 4
[0106] The difference between Comparative Example 4 and Example 1 is that, in step S2, the silicon wafer obtained in step S1 is used as the cathode, the cathode interface is made of iridium-plated titanium metal, the anode material is made of iridium-plated titanium mesh, and the volume ratio of O3, NH4OH, and H2O in the electrolyte is 24:1:50, at 0.8 A / cm 2 Electrolyze at current density and 25°C for 10 minutes, then rinse the silicon wafer with deionized water at 25°C for 5 minutes.
[0107] S3. The silicon wafer obtained in step S2 is subjected to a second electrochemical treatment under the same conditions as in step S2. After the treatment is completed, the silicon wafer is rinsed with deionized water for 5 minutes.
[0108] The silicon wafers of all embodiments and comparative examples were tested after cleaning. The test parameters and methods are as follows:
[0109] (1) Silicon wafer particle residue: The amount of particle residue on the surface of the silicon wafer was tested using a surface defect detector;
[0110] (2) Residual metal ions in silicon wafers: The residual amounts of Mn, K, Na, Mg, Cr, Cu, Fe, Ni, Zn, Ca, Al and Co ions were determined by ICP-MS.
[0111] (3) Surface roughness and damage of silicon wafers: Roughness was tested using a white light interferometer.
[0112] The test results of Example 1 and Comparative Example 1 are shown in Table 1.
[0113] Table 1
[0114]
[0115] The results in Table 1 show that, under the same test conditions, the silicon wafer of Example 1 has less residual particles and metal ions on its surface, and the surface roughness is lower. In contrast, although the silicon wafer of Comparative Example 1 has less residual metal ions, the residual particles and surface roughness are relatively higher. Therefore, the silicon wafer cleaning process provided by this invention can efficiently remove contaminants from the surface of silicon wafers while maintaining a smooth surface, effectively improving the quality of silicon wafers and having broad application prospects.
[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0117] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A silicon wafer cleaning process, characterized in that, The silicon wafer cleaning process includes the following steps: The silicon wafer is first cleaned using a first cleaning solution to remove any residual first cleaning solution from the surface of the silicon wafer. The first cleaning solution includes concentrated H2SO4 and H2O2. The silicon wafer is used as the anode for the first electrochemical treatment to remove the first electrolyte remaining on the surface of the silicon wafer, wherein the first electrolyte includes O3, NH4OH and H2O; The silicon wafer is used as the anode for a second electrochemical treatment to remove the second electrolyte remaining on the surface of the silicon wafer, wherein the second electrolyte includes O3, NH4OH and H2O; The silicon wafer is subjected to a second cleaning process using a second cleaning solution to remove any residual second cleaning solution from the surface of the silicon wafer. The second cleaning solution includes concentrated H2O2, HCl, and H2O. The silicon wafer is subjected to a third cleaning process using a third cleaning solution to remove any residual third cleaning solution from the surface of the silicon wafer. The third cleaning solution includes HF and H2O.
2. The silicon wafer cleaning process according to claim 1, characterized in that, The first electrochemical treatment process satisfies at least one of the following conditions: (1) In the first electrolyte, the volume ratio of O3, NH4OH and H2O is 1:1:10 to 24.7:1:50; (2) The duration of the first electrochemical treatment is 10 min to 15 min; (3) The temperature of the first electrochemical treatment is 20℃~25℃; (4) The current density of the first electrochemical treatment is 0.1 A / cm². 2 ~0.8A / cm 2 ; (5) The cathode material for the first electrochemical treatment is selected from iridium-titanium mesh, platinum-titanium mesh or iridium oxide-coated titanium mesh.
3. The silicon wafer cleaning process according to claim 1, characterized in that, The second electrochemical treatment process satisfies at least one of the following conditions: (1) In the second electrolyte, the volume ratio of O3, NH4OH and H2O is 1:1:10 to 24.7:1:50; (2) The second electrochemical treatment lasts for 10 to 15 minutes; (3) The temperature of the second electrochemical treatment is 20℃~25℃; (4) The current density of the second electrochemical treatment is 0.1 A / cm. 2 ~0.8A / cm 2 ; (5) The cathode material for the second electrochemical treatment is selected from iridium-titanium mesh, platinum-titanium mesh or iridium oxide-coated titanium mesh.
4. The silicon wafer cleaning process according to claim 1, characterized in that, The temperature of the first cleaning process is 115℃~125℃, and the cleaning time is 5min~10min; And / or, in the first cleaning solution, the volume ratio of concentrated H2SO4 to H2O2 is 2:1 to 4:
1.
5. The silicon wafer cleaning process according to claim 1, characterized in that, The temperature for the second cleaning process is 20℃~25℃, and the cleaning time is 5min~10min; And / or, in the second cleaning solution, the volume ratio of concentrated H2O2, HCl and H2O is 1:1:30 to 1:1:
50.
6. The silicon wafer cleaning process according to claim 1, characterized in that, The temperature for the third cleaning process is 20℃~25℃, and the cleaning time is 1min~2min; And / or, in the third cleaning solution, the volume ratio of HF to H2O is 1:20 to 1:
50.
7. The silicon wafer cleaning process according to claim 1, characterized in that, In the first cleaning step of removing residual cleaning fluid from the silicon wafer surface, a deionized water rapid rinsing method is used, with a rinsing temperature of 55℃~65℃ and a rinsing time of 5min~10min.
8. The silicon wafer cleaning process according to claim 1, characterized in that, In the steps of removing the first electrolyte residue, the second electrolyte residue, and the second cleaning solution residue from the silicon wafer surface, deionized water is used to quickly rinse the silicon wafer. The rinsing temperature is independently selected from 20℃ to 25℃, and the rinsing time is independently selected from 5min to 10min.
9. The silicon wafer cleaning process according to claim 1, characterized in that, In the step of removing residual third cleaning solution from the silicon wafer surface, a deionized water overflow rinsing method is used, with a rinsing temperature of 20℃~25℃ and a rinsing time of 5min~10min.
10. The silicon wafer cleaning process according to claim 1, characterized in that, Before the first cleaning process, the silicon wafer is overflow rinsed with deionized water at a temperature of 20°C to 25°C for 5 to 10 minutes.