Unpacking method for preventing silicon polished wafer particles from being contaminated

Abstract

The invention discloses an unpacking method for preventing silicon polished wafer particles from being contaminated, and particularly relates to the technical field of unpacking, and the unpacking method specifically comprises the following steps: S1, outer package removal, S2, outer package bag treatment, S3, air shower purification, S4, inner package removal, S5, silicon wafer extraction, and S6, particle reinspection. Sealing transferring and non-contact type cutting are adopted in the outer packaging bag treatment link, new particles are prevented from being generated in the transferring process, pollution to inner packaging caused by outer packaging residual pollutants is also avoided, and then the air shower purification step is matched for strengthening the first two steps, determining cleaning key points through pre-detection, conducting multi-angle blowing, conducting airflow filtering and conducting pressure control, so that the cleaning efficiency is improved. The particles attached to the surface of the package are removed as much as possible, final particle reinspection is inspection of the effect of the whole unpacking process, and once problems are found, the previous steps can be traced for correction.

Description

Technical Field

[0001] The present invention relates to the technical field of unpacking, and particularly relates to an unpacking method for preventing particle contamination of silicon polished wafers. Background Art

[0002] As a main semiconductor material, silicon polished wafers are the cornerstone of the information age and the basic functional raw materials for semiconductor component products. Globally, approximately 90% of semiconductor components are processed based on silicon polished wafers, and more than 80% of integrated circuits are also based on silicon materials. With the in-depth development of the semiconductor industry, the market demand for silicon polished wafers is increasing, and the quality requirements for silicon polished wafers are also getting higher and higher.

[0003] Silicon polished wafers have numerous quality characteristic parameters. In addition to the chemical purity of the material, crystallographic parameters, electrical parameters, and mechanical geometric dimension parameters after processing of the silicon polished wafers, there are also surface state quality parameters. These quality characteristic parameters jointly determine the quality of silicon polished wafers, and each quality characteristic parameter is extremely important and indispensable. The mechanical geometric dimension parameters and surface state quality parameters are mainly determined during the processing of silicon polished wafers. Therefore, these two quality characteristic parameters are mainly concerned during the processing of silicon polished wafers. Among them, the surface state quality parameters mainly refer to the number of surface particles, surface metal content, and surface nano-morphology of silicon polished wafers. Among them, the number of surface particles of silicon polished wafers not only has a significant impact on the processing yield of subsequent semiconductor components, but also is affected by various factors, resulting in an excessive number of particles. Therefore, it is necessary to control the number of surface particles of silicon wafers not only during the processing of silicon polished wafers, but also to take measures to control the number of surface particles after the processing of silicon polished wafers and before they are used in the subsequent Foundry factory.

[0004] Currently, the existing technology for controlling the surface particles of silicon polished wafers mainly focuses on the processing process of silicon polished wafers, including methods such as adopting advanced cleaning processes, high-grade dust-free environments, high-precision detection equipment, and double-layer vacuum packaging. However, even if the above existing technologies are adopted, if the silicon polished wafers are unpacked improperly when unpacked and used in the subsequent Foundry factory, the silicon polished wafers will still be contaminated with particles during unpacking, resulting in an increase in the number of particles. And because the slot25 groove of the wafer cassette is located on the outermost side of the wafer cassette and the polished surface of the silicon wafer here faces outward, it is easy to adsorb foreign contaminants. Therefore, the number of particles on the silicon wafers here increases more. Summary of the Invention

[0005] The main purpose of the present invention is to provide an unpacking method for preventing particle contamination of silicon polished wafers, which can effectively solve the problems mentioned in the background art.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] A method for unpacking to prevent particle contamination of silicon polishing wafers, comprising the following steps:

[0008] S1, Outer packaging removal: In working room 1, open the outermost packaging box of the silicon polishing wafer and take out the product;

[0009] S2, Outer packaging bag treatment: Transfer the product to working room 2, remove the outer packaging bag of the product, and keep the inner packaging bag;

[0010] S3, Air shower purification: Perform air shower treatment on the product with the inner packaging bag kept, to remove the particles attached to the surface;

[0011] S4, Inner packaging removal: Transfer the air-showered product to clean room 1 and remove the inner packaging bag;

[0012] S5, Silicon wafer extraction: Transfer the product with the inner packaging bag removed to clean room 2, open the packaging box and take out the silicon polishing wafer for subsequent operations;

[0013] S6, Particle re-inspection: After the silicon wafer is extracted, detect the number of particles in the slot25 groove area through a scanning electron microscope (SEM).

[0014] Preferably, the air shower purification in S3 specifically includes the following sub-steps:

[0015] S3a, Preliminary particle detection: Conduct preliminary particle detection on the surface of the inner packaging bag through a laser particle counter, and screen the products with a particle concentration ≥ 50 particles / cubic meter for enhanced air shower;

[0016] S3b, Multi-angle air shower: Adopt a multi-nozzle air shower system to alternately blow the product at jet angles of 30°, 60°, 90° and 120°, covering the top, side and bottom surfaces of the inner packaging bag;

[0017] S3c, Airflow circulation filtration: During the air shower process, purify the circulating air flow in real time through a HEPA filtration system, and monitor the particles with a particle size ≥ 0.1um in the circulating air flow;

[0018] S3d, Dynamic pressure control: Maintain the air pressure in the air shower room at +5 to +10 Pa and form a slightly positive pressure environment.

[0019] Preferably, the silicon wafer extraction in S5 specifically includes the following sub-steps:

[0020] S5a, Nitrogen pre-purging: In clean room 2, inject nitrogen with a purity ≥ 99.99% into the packaging box through a nitrogen purging device for 5 - 10 seconds;

[0021] S5b, Non-contact opening of the box lid: Use a vacuum adsorption robotic arm to adsorb the edge of the packaging box lid and open the box lid in a vertical lifting manner;

[0022] S5c, slot25 groove protection: Before extracting the silicon polishing wafer, cover the slot25 groove area of the wafer cassette with an anti-static silicone sheath, and the surface resistance value of the sheath is 10^6 - 10^9 Ω / sq;

[0023] S5d, transfer one by one: Use a vacuum adsorption chuck to extract the silicon polishing wafers one by one, the adsorption force is controlled at 0.1 - 0.3 MPa, the surface roughness Ra of the chuck is ≤ 0.05 μm, and only one wafer is transferred each time.

[0024] Preferably, in the above S3b, the wind speed of the multi-nozzle air shower system is 12 - 18 m / s, the single air shower time is 40 - 80 seconds, and the nozzle spacing is 20 - 30 cm.

[0025] Preferably, in the above S5c, an ion generator is built into the anti-static silicone sheath to continuously release negative ions to neutralize the static electricity in the groove area, and the ion concentration ≥ 1x10^4 ions / cm 2 。

[0026] Preferably, in the above S5d, the vacuum adsorption chuck is made of fluorinated ethylene propylene copolymer (FEP), and the surface of the chuck is coated with a nano-aluminum oxide anti-sticking layer with a thickness of 50 - 100 nm.

[0027] Preferably, in the above S5a, the air flow rate of the nitrogen purging device is 0.5 - 1.0 m / s, and the purging direction forms a 45° angle with the opening of the wafer cassette.

[0028] Preferably, the operator needs to wear an anti-static one-piece suit and conductive shoes, and pass through ion air bath and ozone sterilization treatment before entering the clean room, and the ozone concentration is controlled at 0.05 - 0.1 ppm.

[0029] Preferably, the cleanliness level of the operation room 1 and operation room 2 is ISO7 (10,000-class environment), and the cleanliness level of the clean room 1 and clean room 2 is ISO4 (10-class environment).

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. In the present invention, through the outer packaging bag treatment process, sealed transportation and non-contact cutting are adopted to prevent the generation of new particles during transportation, and to avoid the pollution of the inner packaging by the residual pollutants on the outer packaging, ensuring that the pollution does not expand further. Secondly, the air shower purification step is a reinforcement of the previous two steps. Through pre-detection to determine the key points of cleaning, multi-angle purging, air flow filtration and pressure control, the particles attached to the packaging surface are removed as much as possible to form a clean product surface state.

[0032] 2. In the present invention, the unpacking of the inner package and the extraction of silicon wafers adopt non-contact operations, anti-static protection, and piece-by-piece transfer because the product is in a relatively clean state after air shower. These operations can avoid introducing new particle contamination due to factors such as mechanical contact and electrostatic adsorption. The final particle re-inspection is to test the effectiveness of the entire unpacking process. Once problems are found, the previous steps can be traced back for correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a schematic diagram of the overall process of the present invention;

[0034] Figure 2 is a schematic diagram of the detection results of particles with a particle size of 0.12 μm for single-box unpacking of the present invention;

[0035] Figure 3 is a schematic diagram of the detection results of particles with a particle size of 0.16 μm for single-box unpacking of the present invention;

[0036] Figure 4 is a schematic diagram of the detection results of particles with a particle size of 0.2 μm for single-box unpacking of the present invention;

[0037] Figure 5 is a schematic diagram of the detection results of particles for multi-box unpacking of the present invention;

[0038] Figure 6 is a schematic diagram of the particle situation with a particle size of 0.12 μm for each box of S1 ot25 grooved silicon polished wafers in Example 4 of the present invention;

[0039] Figure 7 is a schematic diagram of the particle situation with a particle size of 0.16 μm for each box of S1 ot25 grooved silicon polished wafers in Example 4 of the present invention;

[0040] Figure 8 is a schematic diagram of the particle situation with a particle size of 0.20 μm for each box of S1 ot25 grooved silicon polished wafers in Example 4 of the present invention;

[0041] Figure 9 is a schematic diagram of the particle determination map results of the silicon polished wafers partially located in the Slot25 groove of the present invention;

[0042] Figure 10 is a schematic diagram of the structure of the test results of traditional unpacking particles of the present invention;

[0043] Figure 11 is a schematic diagram of the air shower purification process of the present invention;

[0044] Figure 12 is a schematic diagram of the silicon wafer extraction process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0045] To make the technical means, creative features, achieved objectives and effects of the present invention easily understandable, the present invention will be further described below in conjunction with specific embodiments.

[0046] Example 1, as Figure 1 shown, this embodiment provides an unpacking method for preventing particle contamination of silicon polishing wafers, including the following steps:

[0047] S1, Outer packaging removal: In the operation room 1, the operator wears an anti-static one-piece suit and conductive shoes. Before entering, it is necessary to pass through an ion wind bath (to remove human static electricity) and ozone sterilization treatment (ozone concentration 0.05 - 0.1 ppm). Use an anti-static cutting tool with a low particle release rate (such as a polyether ether ketone cutting knife) to disassemble the packaging box. Before cutting, the surface of the tool is subjected to plasma cleaning to remove surface contaminants. Open the outermost packaging box of the silicon polishing wafer and take out the product. After unpacking, only take out the product (retain the inner packaging bag), and the discarded packaging box is directly left in the operation room 1 or sealed and removed. Transferring to other areas is prohibited;

[0048] S2, Outer packaging bag treatment: Transfer the product to the operation room 2. Use a sealed anti-static transfer box during the transfer process. In the operation room 2, the operator uses dust-free gloves and a non-contact cutting tool (such as a laser cutting machine) to remove the outer packaging bag and retain the inner packaging bag. The cutting power is 10 - 20 W to avoid thermal damage or particles. The removed outer packaging bag is immediately sealed and left in the operation room 2. Bringing it into other clean areas is prohibited. Unpacking in separate areas can prevent the spread of outer packaging contaminants to the inner packaging area;

[0049] S3, Air shower purification: Perform air shower treatment on the product with the inner packaging bag retained to remove the particles attached to the surface;

[0050] The air shower purification in S3 specifically includes the following sub-steps. Refer to Figure 11 :

[0051] S3a, Preliminary particle detection: Use a laser particle counter to perform preliminary particle detection on the surface of the inner packaging bag, and screen the products with a particle concentration ≥ 50 particles / cubic meter for enhanced air shower. Preliminary particle detection enables targeted cleaning and optimizes resource allocation;

[0052] S3b, Multi-angle air shower: Adopt a multi-nozzle air shower system to alternately blow the product at jet angles of 30°, 60°, 90° and 120°, covering the top, side and bottom surfaces of the inner packaging bag, which can significantly reduce particle residue;

[0053] Among them, the wind speed of the multi-nozzle air shower system is 12 - 18 m / s, the single air shower time is 40 - 80 seconds, and the nozzle spacing is 20 - 30 cm;

[0054] S3c, air circulation filtration: During the air shower process, the circulating airflow is purified in real time through the HEPA filtration system, with a filtration efficiency of ≥99.99%, and the particles with a size of ≥0.1um in the circulating airflow are monitored; the concentration is ≤10 particles / cubic meter;

[0055] S3d, dynamic pressure control: maintain the air pressure in the air shower room at +5 to +10Pa and form a slightly positive pressure environment to prevent the intrusion of external pollutants;

[0056] The cleanliness of the air shower process is ensured through circulating filtration and positive pressure control to avoid secondary contamination.

[0057] S4, inner packaging removal: transfer the air-showered product to clean room 1 and remove the inner packaging bag;

[0058] S5, silicon wafer extraction: the product with the inner packaging bag removed is transferred to clean room 2, the packaging box is opened and the silicon polishing wafer is taken out for subsequent operations;

[0059] S5 silicon wafer extraction specifically includes the following sub-steps, see Figure 12 :

[0060] S5a, nitrogen pre-purge: In clean room 2, nitrogen with a purity of ≥99.99% is injected into the packaging box through a nitrogen purge device, wherein the air flow speed of the nitrogen purge device is 0.5-1.0m / s, and the purge direction is at a 45° angle to the opening of the film box, which lasts for 5-10 seconds to discharge the residual particles in the box and reduce the risk of particle diffusion when opening the cover;

[0061] S5b, non-contact lid opening: a vacuum suction robot arm is used to suck the edge of the packaging box lid and open the lid by vertical lifting to avoid mechanical contact and particle release;

[0062] S5c, slot 25 groove protection: before extracting the silicon polishing wafer, cover the slot 25 groove area of the wafer box with an antistatic silicone sheath, and the surface resistance of the sheath is 10~6-10~9Ω / sq;

[0063] The anti-static silicone sheath has a built-in ion generator that continuously releases negative ions to neutralize static electricity in the groove area. The ion concentration is ≥1x10^4ions / cm 2 ;

[0064] S5d, piece-by-piece transfer: Use a vacuum suction cup to extract the silicon polished wafers piece by piece, the adsorption force is controlled at 0.1-0.3MPa, the surface roughness of the suction cup Ra≤0.05μm, and only a single piece is transferred each time to reduce friction.

[0065] The vacuum suction cup is made of fluorinated ethylene propylene copolymer (FEP), and the surface of the suction cup is coated with a nano-aluminum oxide anti-sticking layer with a thickness of 50-100 nm.

[0066] S6, Particle re-inspection: After the silicon wafers are extracted, the number of particles in the slot 25 trench area is detected by a scanning electron microscope (SEM) to ensure that the number of particles with a particle size ≥ 0.1 um per unit area (1 cm 2 ) is ≤ 3. If the number of particles per unit area (1 cm 2 ) is > 3, the rework process is triggered, and air shower or nitrogen purging is performed again.

[0067] The cleanliness levels of the above-mentioned working rooms 1 and 2 are ISO 7 (10,000-class environment), and the cleanliness levels of clean rooms 1 and 2 are ISO 4 (100-class environment).

[0068] Example 2, This example uses the unpacking method of Example 1 to unpack a single box of silicon polishing wafers. Specifically:

[0069] Outer packaging removal (S1): In the ISO 7 (10,000-class) working room 1, the operator wears an anti-static one-piece suit and conductive shoes, and undergoes ion air bath (static electricity removal) and ozone sterilization (0.08 ppm).

[0070] Use a polyether ether ketone cutting knife (after plasma cleaning) to disassemble the packing box, take out the product with the inner packaging bag retained, and seal and leave the discarded packing box in working room 1.

[0071] Outer packaging bag treatment (S2): The product is transferred to working room 2 (ISO 7) through an anti-static transfer box.

[0072] Use a laser cutter (power 15 W) to remove the outer packaging bag, and seal and leave the outer packaging bag in working room 2.

[0073] Air shower purification (S3): S3a, Particle pre-detection: Detect the particle concentration on the surface of the inner packaging bag (35 particles per cubic meter), and no enhanced air shower is required. S3b, Multi-angle air shower: Wind speed 15 m / s, time 60 seconds, nozzle spacing 25 cm, covering the top, side and bottom. S3c, Airflow circulation filtration: The HEPA system filters in real time, and the particle concentration of the circulating air flow ≤ 8 particles per cubic meter. S3d, Dynamic pressure control: Maintain the air pressure in the air shower room at +8 Pa.

[0074] Inner packaging removal (S4): The product is transferred to the ISO 4 (100-class) clean room 1, and the inner packaging bag is removed non-contact using dust-free tweezers.

[0075] Silicon Wafer Extraction (S5): S5a, Nitrogen Pre-Purging: Nitrogen purity ≥ 99.99%, gas flow rate 0.8 m / s, purging at 45° for 8 seconds. S5b, Non-Contact Lid Opening: The vacuum adsorption robotic arm (adsorption force 0.1 MPa) vertically opens the cassette lid. S5c, slot25 Groove Protection: Covered with an anti-static silicone sheath (resistance 10^8 Ω / sq), with a built-in negative ion generator (concentration 1.2×10^4 ions / cm 3 ). S5d, Piece-by-Piece Transfer: Using an FEP material suction cup (nano-aluminum oxide coating, thickness 80 nm), adsorption force 0.2 MPa, extracting piece by piece.

[0076] Particle Re-Inspection (S6): SEM detects the slot25 groove area, the number of particles per unit area (1 cm 2 ) is 2 (particle size ≥ 0.1 μm), and the number of particles on all silicon polished wafers meets the standard (≤ 3 particles / cm 2 ), for specific test results, refer to Figures 2 - 4 , and there is no need for rework.

[0077] Example 3: This example uses the unpacking method of Example 1 to unpack multiple boxes of silicon polished wafers (3 boxes, a total of 75 pieces), and the specific operation steps are as follows:

[0078] Outer Packaging Removal (S1): The same as Example 1, disassemble 3 boxes of packaging boxes, and the waste packaging boxes are sealed in batches for treatment.

[0079] Outer Packaging Bag Treatment (S2): Transfer to Workroom 2 in batches, and adjust the laser cutting power to 12 W (to avoid thermal damage).

[0080] Air Shower Purification (S3): S3a, Particle Pre-Detection: The detection values of some boxes reach 55 particles per cubic meter, triggering enhanced air shower (wind speed 18 m / s, time 80 seconds). Other steps are the same as Example 1.

[0081] Inner Packaging Removal (S4) and Silicon Wafer Extraction (S5): The operation process is the same as Example 1, and it is processed in batches.

[0082] Particle Re-Inspection (S6): Randomly extract silicon wafers from the slot25 groove for detection, and the maximum number of particles is 3 per cm 2 , for test results, refer to Figure 5 , meeting the standard, and all 3 boxes of silicon polished wafers meet the requirements.

[0083] Example 4: This example verifies the special protection effect of the slot25 groove on the basis of Example 1, and the specific operation is as follows:

[0084] After the product containing 5 boxes of silicon polishing wafers (125 in total) has gone through the operation steps S1 to S5 above, the silicon polishing wafers in the slot25 groove on the outermost side of the wafer cassette are taken out for particle measurement. The results show that the number of particles of each particle size of the silicon polishing wafers in the slot25 groove in these 5 boxes is very low. The specific particle situation is as follows Figures 6 - 8 , and the particle measurement map of some of the silicon polishing wafers in the Slot25 groove is as follows Figure 9 .

[0085] Comparative example, this comparative example provides a traditional unpacking method, and the specific operation steps are as follows:

[0086] Open the outermost packaging box of the product containing 1 box of silicon polishing wafers in the operation room 1 (10,000-class environment) and take out the product from the packaging box. After that, pass the product through air shower, and then send it to the clean room 1 (10-class environment). At the same time, remove the inner and outer packaging bags of the product and open the lid of the product packaging box. Take out the silicon polishing wafers from the packaging box for particle measurement. The results show that the number of particles with a particle size of 0.20um of the silicon polishing wafers in the slot25 groove in this box exceeds the standard. See specifically Figure 10 .

[0087] Therefore, in this solution, through the sealed transfer and non-contact cutting in the outer packaging bag treatment link, it prevents the generation of new particles during the transfer process, and also avoids the pollution of the inner packaging caused by the residual pollutants on the outer packaging, ensuring that the pollution does not expand further. The air shower purification step is the strengthening of the first two steps. Through pre-detection to determine the cleaning focus, multi-angle blowing, air flow filtration and pressure control, the particles attached to the surface of the packaging are removed as much as possible, forming a clean product surface state

[0088] The non-contact operation, anti-static protection and piece-by-piece transfer are adopted for the removal of the inner packaging and the extraction of the silicon wafers because the product is in a relatively clean state after air shower. These operations can avoid the introduction of new particle pollution due to factors such as mechanical contact and electrostatic adsorption. The final particle re-inspection is the inspection of the effect of the entire unpacking process. Once a problem is found, it is possible to trace back to the previous steps for correction

[0089] Through such an interlocking causal relationship, this unpacking method greatly reduces the risk of particle contamination of silicon polishing wafers, improves the product cleanliness and quality stability. Especially the special protection for the slot25 groove area ensures the quality of the key parts of the silicon wafers and lays a solid foundation for subsequent processing and use

[0090] Compared with the traditional method, this unpacking method, through scientific and reasonable step design and strict operation specifications, significantly reduces the risk of particle contamination of silicon polishing wafers during the unpacking process, improves the product cleanliness and quality stability. Especially the special protection for the slot25 groove area effectively solves the particle contamination problem of the key parts and lays a good foundation for subsequent silicon wafer processing and use

[0091] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and what is described in the above embodiments and the specification is only to illustrate the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements, and these changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A method for unpacking to prevent particle contamination of silicon polishing wafers, characterized in that, It includes the following steps: S1, Outer packaging removal: In the operation room 1, open the outermost packing box of the silicon polished wafer and take out the product; S2, Outer packaging bag treatment: Transfer the product to the operation room 2, remove the outer packaging bag of the product, and keep the inner packaging bag; S3, Air shower purification: Perform air shower treatment on the product with the inner packaging bag kept, to remove the particles attached to the surface; S4, Inner packaging removal: Transfer the air-showered product to the clean room 1 and remove the inner packaging bag; S5, Silicon wafer extraction: Transfer the product with the inner packaging bag removed to the clean room 2, open the packaging box and take out the silicon polished wafer for subsequent operations; S6, Particle re-inspection: After the silicon wafer is extracted, detect the number of particles in the slot 25 groove area through a scanning electron microscope (SEM).

2. The unpacking method for preventing particle contamination of silicon polishing wafers according to claim 1, characterized in that: The S3 air shower purification specifically includes the following sub-steps: S3a, Particle pre-detection: Through a laser particle counter, conduct preliminary particle detection on the surface of the inner packaging bag, and screen the products with a particle concentration ≥ 50 particles / cubic meter for enhanced air shower; S3b, Multi-angle air shower: Adopt a multi-nozzle air shower system, and alternately blow the product at jet angles of 30°, 60°, 90° and 120°, covering the top, side and bottom surfaces of the inner packaging bag; S3c, Airflow circulation filtration: During the air shower process, use a HEPA filtration system to purify the circulating air in real time, and monitor the particles with a particle size ≥ 0.1um in the circulating air; S3d, Dynamic pressure control: Maintain the air pressure in the air shower room at +5 to +10 Pa and form a slightly positive pressure environment.

3. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 1, characterized in that: The S5 silicon wafer extraction specifically includes the following sub-steps: S5a, Nitrogen pre-purging: In the clean room 2, inject nitrogen with a purity ≥ 99.99% into the packaging box through a nitrogen purging device for 5 - 10 seconds; S5b, Non-contact opening of the lid: Use a vacuum adsorption robotic arm to adsorb the edge of the packaging box lid and open the lid in a vertical lifting manner; S5c, slot25 groove protection: Before extracting the silicon polished wafer, cover the slot 25 groove area of the wafer cassette with an anti-static silicone sheath, and the surface resistance value of the sheath is 10~6 - 10~9Ω / sq; S5d, Piece-by-piece transfer: Use a vacuum adsorption chuck to extract the silicon polished wafers piece by piece, control the adsorption force at 0.1 - 0.3 MPa, the surface roughness Ra of the chuck ≤ 0.05μm, and transfer only one piece at a time.

4. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 2, characterized in that: In the S3b, the wind speed of the multi-nozzle air shower system is 12 - 18 m / s, the single air shower time is 40 - 80 seconds, and the nozzle spacing is 20 - 30 cm.

5. The unpacking method for preventing particle contamination of silicon polishing wafers according to claim 3, characterized in that: In the S5c, an ion generator is built into the anti-static silicone sheath, continuously releasing negative ions to neutralize the static electricity in the trench area, and the ion concentration is ≥1x10^4 ions / cm 2 .

6. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 3, characterized in that: In the S5d, the material of the vacuum adsorption chuck is fluorinated ethylene propylene copolymer (FEP), and the chuck surface is coated with a nano-aluminum oxide anti-sticking layer with a thickness of 50 - 100 nm.

7. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 3, characterized in that: In the S5a, the air flow speed of the nitrogen purging device is 0.5 - 1.0 m / s, and the purging direction forms a 45° angle with the opening of the wafer cassette.

8. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 1, characterized in that: The operator needs to wear an anti-static one-piece suit and conductive shoes, and pass through an ion air bath and ozone sterilization treatment before entering the clean room, and control the ozone concentration at 0.05 - 0.1 ppm.

9. A unpacking method for preventing particle contamination of silicon polishing wafers according to claim 1, characterized in that: The cleanliness class of the operation rooms 1 and 2 is ISO 7 (10,000-class environment), and the cleanliness class of the clean rooms 1 and 2 is ISO 4 (100-class environment).

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