A method of manufacturing a substrate

Abstract

The application relates to the technical field of semiconductor manufacturing and substrate processing, and discloses a preparation method of a substrate, which comprises the following steps: attaching a circular ring-shaped film material to a substrate edge region to form physical isolation; performing spin coating glue spreading on the substrate surface, so that excess glue liquid overflows and is attached to the film material surface; heating and baking the substrate to cross-link and solidify the glue liquid; and after cooling, mechanical tension is applied to synchronously tear off the film material and the solidified glue attached to the film material surface, so that edge glue removing treatment of the substrate is completed. The edge removing method combining physical blocking and dry mechanical peeling is used, the problem of glue layer adhesion force reduction of an effective area caused by solvent penetration in traditional wet cleaning is excluded, the cleanliness of the edge glue removing area is ensured, the spraying cleaning and secondary drying processes are omitted, the generation of organic mixed wastewater is avoided from the source, the process preparation period is shortened, the production cost is reduced, and the method can be flexibly applied to substrate processing of different sizes and materials.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing and substrate processing technology, specifically to a method for preparing a substrate. Background Technology

[0002] In semiconductor device manufacturing, the substrate, as a key auxiliary component, is mainly used to support the wafer or other functional layers to be processed. Its surface flatness, edge cleanliness, and other properties directly affect the quality of subsequent processes. Currently, substrates are typically fabricated using 4-8 inch circular glass sheets, sapphire sheets, or silicon wafers with high flatness as the substrate material, with a thickness generally controlled between 1.0-1.5 mm to ensure that the substrate has sufficient structural strength and stability.

[0003] In the substrate fabrication process, spin coating is one of the core steps, used to form a uniform functional adhesive layer on the substrate surface. However, during spin coating, the adhesive inevitably spreads to the edge areas of the substrate and accumulates. If not addressed, this will lead to uneven adhesive layer thickness at the edges after subsequent baking and curing, affecting the flatness and performance of the substrate. In traditional processes, this problem is generally addressed by using a spray cleaning solution to clean the wafer edges. This involves using high-pressure spraying of a specific cleaning solution to flush the substrate edges and remove excess adhesive.

[0004] However, traditional spray cleaning processes have many drawbacks: for example, the cleaning solution can easily penetrate to the interface between the functional adhesive layer and the substrate, affecting the adhesion of the adhesive layer and causing it to peel off during subsequent use; the impact force generated during spraying may cause damage or peeling of the adhesive layer at the substrate edge, compromising the integrity of the adhesive layer; an additional drying step is required after cleaning, which not only prolongs the preparation cycle but also increases energy consumption and production costs; the use of cleaning solution generates industrial wastewater, resulting in high subsequent treatment costs, which is not in line with the development trend of green manufacturing; for substrates with high precision requirements, spray cleaning makes it difficult to accurately control the cleaning range and intensity, which can easily lead to a decrease in the flatness of the substrate edges and affect the product qualification rate.

[0005] Therefore, there is a need for a preparation method that can avoid the defects of traditional spray cleaning processes while ensuring the quality of substrate edges. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a method for preparing a substrate, which solves the problems in substrate homogenization preparation, where traditional chemical wet edge removal processes easily lead to solvent penetration, resulting in decreased adhesion of the adhesive layer in the effective area, as well as generating a large amount of organic wastewater and having a cumbersome preparation process.

[0007] To achieve the above objectives, the present invention provides a method for preparing a substrate, employing the following technical solution:

[0008] A substrate material is provided, and the substrate material is cleaned and dried to obtain a pretreated substrate.

[0009] A ring-shaped film material is provided, comprising a substrate layer and an adhesive layer, wherein the outer ring diameter of the ring-shaped film material is larger than the diameter of the pretreated substrate, and the inner ring diameter is smaller than the diameter of the pretreated substrate.

[0010] The annular film is attached to the surface of the pretreated substrate through the adhesive layer to obtain a substrate covered with the film.

[0011] An adhesive is applied to the surface of the substrate covered with the film material, so that the adhesive covers the central effective area of ​​the substrate and the surface of the annular film material, thereby obtaining a substrate with the adhesive coating on its surface.

[0012] The substrate coated with adhesive is heated and baked to completely cure the adhesive and form an adhesive layer, resulting in a baked substrate.

[0013] After the baked substrate cools to room temperature, pinch the protruding part of the outer ring of the annular film that is exposed at the edge of the substrate and slowly peel off the film. The adhesive layer attached to the film at the edge of the substrate is peeled off along with the film, leaving the intact cured adhesive layer in the effective area of ​​the substrate, thus completing the preparation of the substrate.

[0014] By employing the above technical solution, the physical isolation zone established by the pre-defined annular film material prevents direct contact between excess adhesive and the substrate edge surface. Its edge removal mechanism and interface evolution process include the following steps:

[0015] The first step is the fluid dynamics flow obstruction stage. Driven by the centrifugal force generated during spin coating, the fluid adhesive undergoes radial displacement from the center of the substrate to the periphery. The film material attached to the edge forms microscopic geometric steps due to its own thickness. When the adhesive crosses the effective area at the center of the substrate and enters the surface of the film material, the fluid kinetic energy decreases due to the abrupt interface change, causing the adhesive to stagnate and adhere within the film material area, intercepting the fluid that would spread to the edge or even the back of the substrate.

[0016] The second step is the thermodynamic cross-linking and curing stage. The applied heat energy drives the movement of polymer chain segments, causing the active groups between adhesive molecules to react and form a three-dimensional network structure. The excess adhesive layer after curing bonds to the surface of the annular film material.

[0017] The third step is the interfacial mechanical peeling stage. After the system cools to room temperature, the cohesion and interfacial energy of the system reach a steady state. During the peeling process, when the applied external mechanical tensile force is greater than or equal to the sum of the interfacial adhesion work between the adhesive layer of the film and the substrate surface and the energy dissipation generated by the deformation of polymer chain segments during the separation process, the interface undergoes fracture cleavage, and the excess cured adhesive layer accumulated on the surface is peeled off as a whole along with the underlying film.

[0018] This method employs physical mechanical peeling instead of chemical solvent rinsing, eliminating the cleaning fluid medium and cutting off the capillary path for solvent molecules to diffuse and penetrate along the bonding interface. This prevents the functional adhesive layer in the central effective area from experiencing reduced adhesion due to microscopic swelling. The resulting physical boundary after membrane removal is clean, eliminating edge smoothness defects caused by residual rinsing droplets. Simultaneously, this solution transforms the fluid polymer into solid waste adhering to the membrane material, avoiding the generation of organic industrial wastewater.

[0019] Preferably, the specific operations for cleaning and drying the substrate material are as follows:

[0020] The substrate material is placed in an ultrasonic cleaning tank, and a neutral detergent aqueous solution is used as the cleaning solution. Ultrasonic cleaning is performed at an ultrasonic frequency of 40-60kHz for 10-20 minutes.

[0021] The substrate is then rinsed with deionized water and finally dried in an oven at 60-80°C for 20-30 minutes to obtain the pretreated substrate.

[0022] By employing the above technical solution, the ultrasonic cavitation effect at a specific frequency forms microbubbles in the liquid medium. The microjet generated by the bursting of these bubbles peels off particles and organic contaminants from the substrate surface. The drying process with set parameters removes residual moisture from the surface, increases the surface tension of the substrate, provides an adhesion interface for the adhesive layer of the film, and prevents lateral slippage of the film during high-speed spin coating.

[0023] Preferably, the specific operations for providing the annular membrane material include:

[0024] A film material composed of a substrate layer with a thickness of 50-100μm and an adhesive layer with a thickness of 5-15μm is selected;

[0025] The membrane material is cut into a circular ring structure using a laser cutting process to obtain the circular ring membrane material, and the cutting accuracy is controlled within ±0.1mm.

[0026] In the laser cutting process, the outer ring diameter of the annular film is cut to be 2-20 mm larger than the diameter of the substrate, and the ring width of the annular film is cut to be 2-10 mm.

[0027] The substrate layer is made of any one of polyethylene terephthalate, polyethylene, or polyvinyl chloride;

[0028] The adhesive layer is an acrylic adhesive layer.

[0029] By employing the above technical solution, a substrate layer with a thickness of 50-100μm provides the tensile yield strength required to withstand mechanical peel loads, preventing film breakage during peeling. The high-energy-density laser beam enables instantaneous thermal melting and vaporization of the thin film material, resulting in smooth cutting edges. A cutting accuracy of ±0.1mm ensures a high degree of consistency in the physical isolation boundaries.

[0030] The outer ring diameter, which is 2-20 mm larger than the substrate, provides a stress-bearing end free of adhesive adhesion for the subsequent peeling process. The 2-10 mm ring width provides ample area for dissipating fluid kinetic energy. The selected polymer substrate maintains the stability of its molecular chain structure under the high-temperature baking and curing environment, preventing thermal shrinkage stress at the interface.

[0031] Preferably, the operation of attaching the annular film material to the edge surface of the pretreated substrate is carried out in a Class 1000 cleanroom, with the ambient temperature controlled at 20-25°C and the relative humidity controlled at 40%-60% during attachment.

[0032] Furthermore, after the application is completed, the film surface is pressed using a silicone roller.

[0033] By employing the above technical solution, a specific temperature and humidity range maintains the appropriate flexibility of the polymer chain segments in the adhesive layer. Applying uniform static pressure using a silicone roller eliminates micro-air bubbles at the bonding interface, ensuring full adhesion between the adhesive layer and the substrate, eliminating interfacial gaps, and preventing bottom lateral penetration of the adhesive during spin coating.

[0034] Preferably, the specific implementation of coating the substrate surface covered with the film material at the edge with the adhesive is as follows:

[0035] A spin coater was used to perform spin coating on the substrate surface, with the spin coating speed controlled at 1000-5000 r / min and the spin coating time at 30-60 s.

[0036] The process parameters for heating and baking the substrate with the adhesive coating on its surface are as follows:

[0037] The baking temperature is 80-150℃, and the baking time is 30-90 minutes.

[0038] By adopting the above technical solution, the set spin coating parameters control the film thickness distribution of the fluid on the substrate surface. The temperature range of 80-150℃ provides the activation energy required to activate the initiator in the adhesive system, completing the transformation from monomer to bulk polymer; at the same time, this heat input parameter does not exceed the critical thermodynamic barrier for irreversible chemical crosslinking of the adhesive layer, maintaining the physical adhesion properties of the interface and ensuring the smooth peeling of the subsequent film material.

[0039] Preferably, the substrate material is a 4-8 inch circular glass sheet, sapphire sheet, or silicon wafer;

[0040] The thickness of the substrate material is controlled to be 1.0-1.5 mm;

[0041] The coating adhesive is a photoresist or a polydimethylsiloxane adhesive.

[0042] By adopting the above technical solution, the physical-mechanical edge removal method eliminates the compatibility limitations of different underlying material surfaces and specific chemical solvents. This physical barrier method can adapt to the intrinsic surface energy properties of silicon, sapphire, and inorganic glass, and is compatible with photosensitive polymers and silicon-based elastomer liquids of different viscosities and crosslinking mechanisms, thus expanding the application range of wafer-assisted substrate processes.

[0043] This invention provides a method for preparing a substrate. It has the following advantages:

[0044] 1. This invention replaces the traditional solvent spray cleaning process by pre-attaching a circular film to the edge of the substrate and then physically peeling it off after curing. This edge removal method, combining physical blocking and mechanical peeling, directly eliminates the risk of liquid cleaning agent capillary penetration along the substrate-adhesive layer interface, preventing adhesion degradation in the central effective area due to swelling. Simultaneously, any adhesive overflowing to the edge is completely peeled off along with the film, eliminating adhesive residue caused by liquid rinsing at the substrate edge and ensuring edge smoothness and surface quality.

[0045] 2. This invention utilizes the attached membrane material to collect the fluid adhesive that overflows during the homogenization process. After being cured by heat, the liquid is directly removed as solid waste along with the membrane material, eliminating the chemical spray cleaning and secondary drying and drainage steps required in traditional processes. This change not only reduces process nodes and substrate transfer time, improving preparation efficiency, but also cuts off the source of industrial cleaning wastewater containing high concentrations of polymers, eliminating the expenses of purchasing cleaning solvents and environmentally friendly wastewater treatment, and reducing equipment investment and overall production costs.

[0046] 3. The preparation process provided by this invention has good backward compatibility. The inner and outer ring dimensions of the annular film can be flexibly adjusted through conventional cutting processes, and can directly match the shape of substrates of different specifications such as 4 inches to 8 inches. Since it uses a purely physical mechanism to isolate and remove excess adhesive, it does not depend on the interface chemical properties of specific materials, and can be stably applied to various underlying materials such as silicon wafers, sapphire wafers, and glass wafers. It can also adapt to the preparation requirements of different coating adhesives such as photoresist or polydimethylsiloxane. Attached Figure Description

[0047] Figure 1 This is a surface contour scan curve of the adhesive removal area at the edge of the substrate in Examples 1 to 3 of the present invention, as shown in Test Example 1 of the present invention.

[0048] Figure 2 This is a bar chart showing the percentage of cured adhesive layer peeling area in different regions of Examples 1 to 3 in Test Example 2 of the present invention;

[0049] Figure 3 This is a dual Y-axis distribution diagram comparing the preparation efficiency and wastewater discharge of Example 2 and Comparative Example 1 in Test Example 3 of the present invention;

[0050] Figure 4 This is a curve comparison of the adhesive spread test data at the edge and back of Example 2 and Comparative Example 2 in Test Example 4 of the present invention;

[0051] Figure 5 This is a distribution diagram of the average peel force and water contact angle of the degummed area of ​​the film material after high-temperature baking in Example 2 and Comparative Example 3 of the present invention in Test Example 5 of the present invention;

[0052] Figure 6 This is a process flow diagram of a substrate preparation method according to an embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of the structure of the substrate to be uniformly coated in an embodiment of the present invention;

[0054] Figure 8 This is a schematic diagram of the structure for preparing the annular membrane material in an embodiment of the present invention;

[0055] Figure 9 This is a schematic diagram of the structure after the annular film material is attached to the substrate to be uniformly coated with adhesive in an embodiment of the present invention;

[0056] Figure 10 This is a schematic diagram of the substrate structure after homogenization and baking in an embodiment of the present invention;

[0057] Figure 11 This is a schematic diagram of the substrate structure after the annular film is removed in an embodiment of the present invention. Detailed Implementation

[0058] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Combination Figures 7 to 11 The interface evolution and physical state of the substrate preparation method of the present invention are illustrated in the figure:

[0060] First, such as Figure 7 As shown, substrate selection and pretreatment are performed to obtain a clean circular substrate body.

[0061] Subsequently, as Figure 8 As shown, a ring-shaped film material is prepared for physical barrier. To ensure that it can completely cover the edge of the substrate and is easy to remove, the outer ring diameter of the ring-shaped film material is set to be larger than the diameter of the pretreated substrate, and its inner ring diameter is smaller than the diameter of the substrate.

[0062] Next, as Figure 9 As shown, the aforementioned annular film material is attached to the edge surface of the substrate using an adhesive layer. Since the outer ring of the film material is larger than the substrate and the inner ring is smaller than the substrate, after attachment, the outer ring portion of the film material will protrude outward from the substrate, while the inner ring portion will be tightly adhered to the edge surface of the substrate, thereby establishing a physical water-blocking / adhesive-blocking barrier with microscopic geometric steps at the edge of the substrate.

[0063] like Figure 10 As shown, after completing the spin coating and heating baking processes, the flowing adhesive diffuses outward from the center of the substrate, covering the effective central area of ​​the substrate and the surface of the annular film. After the thermodynamic cross-linking and curing stage, the excess edge adhesive layer combines with the surface of the annular film to form a solid whole (the dark gray covered area in the figure).

[0064] Ultimately, as Figure 11 As shown, after the system cools to room temperature, external mechanical force is applied to pinch and peel off the protruding part of the film material exposed at the edge of the substrate. The interface fractures and cleaves, and the edge-cured adhesive layer attached to the film material is simultaneously and completely peeled off. After peeling, the effective area in the middle of the substrate retains the complete cured adhesive layer (dark area in the figure), while the clean underlying substrate is exposed at the edge of the substrate (light-colored outer circle area in the figure). This achieves a solvent-free, high-flatness dry edge removal effect, completing the substrate preparation.

[0065] Preparation Examples 1-3:

[0066] Preparation Example 1:

[0067] This preparation example provides a method for preparing an annular film material for substrate preparation, including the following steps:

[0068] A membrane material is provided, comprising a substrate layer and an adhesive layer (the adhesive layer being an acrylic adhesive layer). The substrate layer is made of polyethylene terephthalate (PET) and has a thickness of 50 μm. An acrylic adhesive layer is coated on one side of the substrate layer, and the thickness of the adhesive layer is controlled to be 5 μm. The membrane material is cut into a circular ring structure using a laser cutting process. The outer ring diameter of the circular ring membrane material is set to be 2 mm larger than the diameter of the target substrate, and the width of the ring is set to be 2 mm. The cutting accuracy is controlled within ±0.1 mm.

[0069] Preparation Example 2:

[0070] This preparation example provides a method for preparing an annular film material for substrate preparation, including the following steps:

[0071] A membrane material is provided, comprising a substrate layer and an adhesive layer (the adhesive layer being an acrylic adhesive layer), wherein the substrate layer is made of polyethylene (PE) and has a thickness of 80 μm; the acrylic adhesive layer is coated on one side of the substrate layer, and the thickness of the adhesive layer is controlled to be 10 μm; the membrane material is cut into a circular ring structure using a laser cutting process, wherein the outer ring diameter of the circular ring membrane material is set to be 3 mm larger than the diameter of the target substrate, the width of the ring is set to be 5 mm, and the cutting accuracy is controlled to be ±0.1 mm.

[0072] Preparation Example 3:

[0073] This preparation example provides a method for preparing an annular film material for substrate preparation, including the following steps:

[0074] A membrane material is provided, comprising a substrate layer and an adhesive layer (the adhesive layer being an acrylic adhesive layer), wherein the substrate layer is made of polyvinyl chloride (PVC) and has a thickness of 100 μm; the acrylic adhesive layer is coated on one side of the substrate layer, and the thickness of the adhesive layer is controlled to be 15 μm; the membrane material is cut into a circular ring structure using a laser cutting process, wherein the outer ring diameter of the circular ring membrane material is set to be 20 mm larger than the diameter of the target substrate, the width of the ring is set to be 10 mm, and the cutting accuracy is controlled to be ±0.1 mm.

[0075] Reference Figure 6 This invention provides a method for preparing a substrate, the overall process of which mainly includes: substrate selection and pretreatment, film preparation, film application, homogenization, baking and curing, and film removal. The preparation method of this invention will be further described in detail below with reference to specific preparation examples and embodiments.

[0076] Examples 1-3:

[0077] Example 1:

[0078] This embodiment provides a method for preparing a substrate, including the following steps:

[0079] Substrate selection: Select a 4-inch circular silicon wafer with a thickness of 1.0 mm as the substrate material; place the silicon wafer in an ultrasonic cleaning tank, use a neutral detergent aqueous solution as the cleaning solution, ultrasonic frequency 40 kHz, cleaning time 10 min; then rinse with deionized water for 5 min, place in an oven, dry at 80℃ for 20 min to complete the pretreatment.

[0080] Membrane material preparation: Select a membrane material with a PET substrate layer thickness of 50um and an acrylic adhesive layer thickness of 5um; use laser cutting technology to cut the membrane material into a ring shape, with the outer ring diameter being 2mm larger than the silicon wafer diameter, the ring width being 2mm, and the cutting accuracy controlled within ±0.1mm.

[0081] Membrane application: The application operation is carried out in a Class 1000 cleanroom with an ambient temperature of 20°C and a relative humidity of 40%. The circular membrane is applied to the surface of the pretreated silicon wafer through an acrylic adhesive layer, ensuring that the center of the membrane coincides with the center of the silicon wafer. A silicone roller is used to press the surface of the membrane to remove air bubbles and ensure a tight fit.

[0082] Spin coating process: A spin coater is used to coat the substrate surface with photoresist (selected). The spin coating speed is 3000 r / min and the spin coating time is 30s, so that the photoresist can evenly cover the effective area of ​​the silicon wafer and the surface of the film.

[0083] Baking and curing: Place the silicon wafer after photoresist homogenization into an oven and bake at 80°C for 90 minutes to completely cure the photoresist.

[0084] Film removal: After the silicon wafer cools to room temperature, pinch the protruding part of the outer ring of the film and slowly peel off the film. The photoresist at the edge of the silicon wafer is removed along with the film, and the effective area retains the complete cured photoresist layer, thus completing the substrate preparation.

[0085] Example 2:

[0086] This embodiment provides a method for preparing a substrate, including the following steps:

[0087] Substrate selection: A 6-inch circular sapphire sheet with a thickness of 1.2 mm was selected as the substrate material. The sapphire sheet was placed in an ultrasonic cleaning tank, and a neutral detergent aqueous solution was used as the cleaning solution. The ultrasonic frequency was 50 kHz and the cleaning time was 15 min. Then, it was rinsed with deionized water for 8 min and placed in an oven to dry at 70℃ for 25 min to complete the pretreatment.

[0088] Membrane material preparation: Select a membrane material with a polyethylene (PE) substrate layer thickness of 80um and an acrylic adhesive layer thickness of 10um; use laser cutting technology to cut the membrane material into a ring shape, with the outer ring diameter being 3mm larger than the sapphire sheet diameter, the ring width being 5mm, and the cutting accuracy controlled within ±0.1mm.

[0089] Membrane application: The application operation is carried out in a Class 1000 cleanroom with an ambient temperature of 23°C and a relative humidity of 50%. The circular membrane material is applied to the surface of the pretreated sapphire sheet through an acrylic adhesive layer, ensuring that the center of the membrane material coincides with the center of the sapphire sheet. A silicone roller is used to press the surface of the membrane material to remove air bubbles and ensure a tight fit.

[0090] Spin coating process: The adhesive liquid (polydimethylsiloxane (PDMS)) is applied to the substrate surface using a spin coater at a speed of 3000 r / min and a spin coating time of 45 s, so that the insulating adhesive can evenly cover the effective area of ​​the sapphire wafer and the surface of the film.

[0091] Baking and curing: Place the homogenized sapphire sheet into an oven and bake at 120℃ for 60 minutes to fully cure the PDMS adhesive.

[0092] Film removal: After the sapphire sheet has cooled to room temperature, pinch the protruding part of the outer ring of the film and slowly peel the film off from the substrate. The polydimethylsiloxane (PDMS) adhesive on the edge of the sapphire sheet is removed along with the film, while the effective area in the middle retains the fully cured polydimethylsiloxane (PDMS) adhesive layer, thus completing the substrate preparation.

[0093] Example 3:

[0094] This embodiment provides a method for preparing a substrate, including the following steps:

[0095] Substrate selection: Select an 8-inch circular glass sheet as the substrate material with a thickness of 1.5mm; place the glass sheet in an ultrasonic cleaning tank, use a neutral detergent aqueous solution as the cleaning solution, ultrasonic frequency 60kHz, cleaning time 20min; then rinse with deionized water for 10min, place in an oven, dry at 60℃ for 30min to complete the pretreatment.

[0096] Membrane material preparation: Select a membrane material with a polyvinyl chloride (PVC) substrate layer thickness of 100um and an acrylic adhesive layer thickness of 15um; use laser cutting technology to cut the membrane material into a ring shape, with the outer ring diameter being 20mm larger than the glass sheet diameter, the ring width being 10mm, and the cutting accuracy controlled within ±0.1mm.

[0097] Membrane application: The application operation is carried out in a Class 1000 cleanroom with an ambient temperature of 25°C and a relative humidity of 60%. The circular membrane is applied to the surface of the pretreated glass sheet through an acrylic adhesive layer, ensuring that the center of the membrane coincides with the center of the glass sheet. A silicone roller is used to press the surface of the membrane to remove air bubbles and ensure a tight fit.

[0098] Spin coating process: A spin coater is used to coat the substrate surface with photoresist (using a spin coater). The spin coater speed is 5000 r / min and the spin coat time is 60 s, so that the photoresist can evenly cover the effective area of ​​the glass sheet and the surface of the film.

[0099] Baking and curing: Place the glass slide after photoresist homogenization into an oven and bake at 150℃ for 30 minutes to completely cure the photoresist.

[0100] Film removal: After the glass sheet cools to room temperature, pinch the protruding part of the outer ring of the film and slowly peel off the film. The photoresist at the edge of the glass sheet is removed along with the film, and the effective area retains the complete cured photoresist layer, thus completing the substrate preparation.

[0101] Example 4:

[0102] This embodiment provides a method for preparing a substrate, including the following steps:

[0103] Substrate selection: A 6-inch circular silicon wafer with a thickness of 1.1 mm was selected as the substrate material. The silicon wafer was placed in an ultrasonic cleaning tank, and a neutral detergent aqueous solution was used as the cleaning solution. The ultrasonic frequency was 45 kHz and the cleaning time was 12 min. Then, it was rinsed with deionized water for 6 min and placed in an oven to dry at 75 ℃ for 20 min to complete the pretreatment.

[0104] Membrane material preparation: Select a membrane material with a polyethylene terephthalate (PET) substrate layer thickness of 60um and an acrylic adhesive layer thickness of 8um; use laser cutting process to cut the membrane material into a ring shape, with the outer ring diameter being 10mm larger than the silicon wafer diameter, the ring width being 8mm, and the cutting accuracy controlled within ±0.1mm.

[0105] Membrane application: The application operation is carried out in a Class 1000 cleanroom with an ambient temperature of 22℃ and a relative humidity of 45%. The circular membrane is applied to the surface of the pretreated silicon wafer through an acrylic adhesive layer, ensuring that the center of the membrane coincides with the center of the silicon wafer. A silicone roller is used to press the surface of the membrane to remove air bubbles and ensure a tight fit.

[0106] Spin coating process: The adhesive (polydimethylsiloxane (PDMS) adhesive) is applied to the substrate surface using a spin coater at a speed of 1000 r / min and a spin coating time of 40 s, so that the PDMS adhesive can evenly cover the effective area of ​​the silicon wafer and the surface of the film.

[0107] Baking and curing: Place the silicon wafer after homogenization into an oven and bake at 100℃ for 80 minutes to fully cure the PDMS adhesive.

[0108] Film removal: After the silicon wafer cools to room temperature, pinch the protruding part of the outer ring of the film and slowly peel the film off the substrate. The polydimethylsiloxane (PDMS) adhesive on the edge of the silicon wafer is removed along with the film, and the effective area retains the fully cured polydimethylsiloxane (PDMS) adhesive layer, thus completing the substrate preparation.

[0109] Comparative Examples 1-3:

[0110] Comparative Example 1:

[0111] Compared with Example 2, the difference is that no annular film material was attached, and after the adhesive coating process, the substrate edge was rinsed with high-pressure spray cleaning liquid to remove excess adhesive. An additional drying step was added after cleaning, and there was no final film removal step. All other aspects are the same.

[0112] Comparative Example 2:

[0113] Compared with Example 2, the difference is that in the preparation of the membrane material, the width of the annular membrane material is only 1 mm, while the rest are the same.

[0114] Comparative Example 3:

[0115] Compared with Example 2, the difference is that in the preparation of the membrane material, the acrylic adhesive layer of the membrane material is replaced with a common epoxy resin adhesive layer, and the rest are the same.

[0116] Test Examples 1-5:

[0117] Test Example 1: Cleanliness and Thickness Test of Edge Adhesive Removal Area

[0118] The substrates prepared in Examples 1 to 3 were placed on the vacuum chuck stage of the stepper, and the vacuum pump was turned on to fix the substrates.

[0119] Adjust the position of the test probe, set the starting scan point to the adhesive removal area at the outermost edge of the substrate, the scan path is radially directed towards the center of the substrate, and the scan length is set to cross the boundary between the adhesive removal area and the central effective adhesive layer area.

[0120] The probe contact force was set to 2 mg, and the scanning speed to 50 μm / s. Repeated scanning tests were performed on each substrate sample using radial paths at four different orientations: 0°, 90°, 180°, and 270°.

[0121] Extract the probe's contour scanning data in the desizing area, calculate the average thickness increment of the area, i.e., the difference between the actual measured thickness of the desizing area and the nominal thickness of the bare substrate; at the same time, extract the surface roughness Ra value of the desizing area using instrument software.

[0122] Table 1. Test data on the thickness and roughness of the adhesive removal area at the substrate edge in Examples 1-3

[0123] Based on the data in Table 1 and Figure 1 The surface profile scans show that the thickness increment of the degummed area in Examples 1 to 3 is between 1.4 nm and 7.1 nm, and the surface roughness Ra value is between 0.51 nm and 1.22 nm. Figure 1 The scanning distance of 0 to 2.5 mm corresponds to the edge of the substrate where the adhesive is removed. The relative height of this range is close to 0 and the fluctuation range is on the nanometer scale. There is no accumulation of micron-level residual adhesive thickness. After the scanning probe crosses the boundary area, the profile curve rises in a step-like manner and remains highly stable in the central effective area of ​​2.5 to 5 mm.

[0124] Test data and graph morphology indicate that there is no photoresist or PDMS adhesive residue at the substrate edge. The acrylic adhesive layer was peeled off along with the substrate layer after high-temperature curing at 80℃ to 150℃, and the surface morphology of the adhesive-removed area is consistent with the original characteristics of the bare substrate. The annular film attached to the substrate edge forms a physical isolation layer, preventing the spread of adhesive to the edge during the homogenization process; the subsequent dry peeling operation uses mechanical stress to simultaneously peel off the edge adhesive layer attached to the film.

[0125] This physical edge removal mechanism eliminates the problem of interface adhesion degradation caused by the penetration of cleaning solvent into the adhesive layer in wet cleaning processes. At the same time, it avoids structural damage or secondary contamination caused by high-pressure fluid flushing to the substrate edge. It ensures the cleanliness of the edge adhesive removal area and the integrity of the transition between the effective central area and the substrate under different substrates and adhesive systems.

[0126] Test Example 2: Adhesive Adhesion Test in the Central Effective Area

[0127] The substrates prepared in Examples 1 to 3 were horizontally fixed on the test stage. Three different locations were selected as test areas on the surface of the cured adhesive layer in the effective area of ​​the substrate center: the center point, the radius 1 / 2 point, and the point near the boundary edge.

[0128] Use a cross-cutting tool to create a 10×10 grid on the selected test area surface, with the scratch spacing set to 1mm. Control the pressure applied by the tool to make the cutting depth penetrate the cured adhesive layer and reach the substrate surface below.

[0129] Use a soft-bristled brush to gently clean the adhesive residue from the surface along the diagonal of the grid to remove any loose particles that could interfere with the subsequent bonding process.

[0130] Apply the 3M 600 standard test tape to the surface of the grid area, and use a rubber roller to apply constant pressure to the tape surface and roll it back and forth 3 times to remove residual air bubbles at the interface between the tape and the adhesive layer.

[0131] After letting the tape sit for 90 seconds, pinch one end of the tape and peel it off smoothly at an angle of approximately 180° within 0.5 to 1.0 seconds.

[0132] Use a magnifying glass with illumination to observe the peeling of the adhesive layer in the grid area, record the number of peeled grids, calculate the percentage of the peeled area to the total grid area, and determine the adhesion level of each test point according to the ASTM D3359 standard.

[0133] Table 2. Adhesion test data of effective area adhesive layer in Examples 1-3

[0134] According to Table 2 and Figure 2 The adhesion test results of the cured adhesive layer in different areas showed that the effective area of ​​adhesive layer peeling off in Examples 1 to 3 accounted for the highest proportion of 1.6%, while the values ​​of other test points were mostly distributed in the range of 0% to 1.1%. The overall adhesion rating was at level 4B and 5B.

[0135] Figure 2 The column height distribution in the data shows that, at the center point, half radius, and near the edge of the same substrate, the adhesive layer peeling rate did not exhibit a significant deterioration trend with increasing radial distance. The data distribution characteristics indicate that the adhesion strength of the photoresist and PDMS adhesive to different substrate surfaces remains stable after the edge annular film is removed.

[0136] The physical edge removal process confines mechanical stress to the film attachment area outside the substrate, with adhesive layer fracture occurring at the inner ring boundary of the film. This fracture process consumes the shear energy generated during tearing, preventing stress from propagating along the cured adhesive layer network towards the substrate center. In traditional cleaning processes, solvents easily penetrate the interface from the junction, leading to decreased adhesion of the edge adhesive layer. This solution avoids contact between liquid media and the cured adhesive layer through mechanical tearing, eliminating the risk of solvent swelling damaging the interfacial van der Waals forces. The low peeling rate of 0% to 1.6% near the edge proves that the adhesive layer at the edge did not develop lifting or microcracks due to film tearing, confirming that the dry edge removal mechanism maintains the integrity of the overall physical properties of the adhesive layer in the effective area.

[0137] Test Example 3: Evaluation of Preparation Efficiency and Environmental Impact

[0138] Using 25 6-inch sapphire wafers as a test batch, the substrate preparation process of Example 2 and Comparative Example 1 was executed separately, with each scheme being repeated independently for 3 batches.

[0139] An electronic stopwatch was used to record the total process flow time for a single batch. The starting point of the timing was set to the moment when the substrate was removed from the oven after pretreatment and entered the spin coating workshop, and the ending point of the timing was set to the moment when the finished substrate with clean edges was obtained.

[0140] For Comparative Example 1, a sealed collection tank with volume markings was connected to the drain port below the edge cleaning device after the uniform coating process to collect all the mixed waste liquid generated by the high-pressure spraying of excess PDMS adhesive at the edge of the substrate.

[0141] After the single-batch cleaning process of Comparative Example 1 was completed, the total volume of waste liquid in the collection bucket was recorded, and 50 mL of mixed waste liquid was extracted using a pipette as a sample. The chemical oxygen demand of the sample was determined using the dichromate method.

[0142] In Example 2, during the single-batch membrane removal process, the polyethylene annular membranes with PDMS cured adhesive on their surfaces that are torn off are collected and weighed on an industrial electronic balance with an accuracy of 0.01g to determine the total mass of solid waste.

[0143] Table 3. Preparation efficiency and waste test data of Example 2 and Comparative Example 1

[0144] The "-" indicates that no mixed waste liquid was generated, therefore there is no test data for this item.

[0145] According to Table 3 and Figure 3 Based on the data, the average total time for the three batches in Example 2 was 90.1 min, and the amount of mixed waste liquid generated was 0 L; the average total time for Comparative Example 1 was 151.1 min, and the average amount of mixed waste liquid generated was 4.38 L. Test results and Figure 3 The dual Y-axis distribution pattern reflects the correlation between the process cycle and the amount of liquid phase wastewater discharged.

[0146] Comparative Example 1 used a high-pressure spraying device to rinse the uncured PDMS adhesive at the substrate edge. This process incorporated rinsing spraying and subsequent secondary drying and draining of the substrate, extending the overall process cycle. The cleaning solvent used in the spraying dissolved the polydimethylsiloxane at the silicon wafer edge, forming a high-concentration organic mixture with a chemical oxygen demand (COD) ranging from 3620 mg / L to 4150 mg / L, increasing the load on the wastewater treatment system. Example 2 used a pre-placed polyethylene annular film as a physical mask interface at the substrate edge; the fluid adhesive overflowing during the spin coating process deposited on the film surface.

[0147] In the subsequent 120°C heating and baking process, the deposited adhesive and the adhesive in the central effective area simultaneously undergo a cross-linking reaction to solidify into a film. After cooling to room temperature, mechanical tension is applied to complete the dry separation. This dry process eliminates the solvent rinsing and secondary drainage baking equipment steps, reducing the process time per batch. The uncured liquid adhesive transforms into a solid deposit upon heating, forming approximately 14g to 15g of industrial solid waste along with the discarded membrane material, thus eliminating the source of high-concentration cleaning wastewater.

[0148] Test Example 4: Edge Adhesive Spread Isolation Test

[0149] The substrates prepared in Example 2 and Comparative Example 2, after the film material has been peeled off, were fixed on the rotating stage of the step tester, and vacuum adsorption was turned on and horizontal calibration was performed.

[0150] Set the scanning path of the step profiler probe, starting at the outermost physical edge of the substrate, and scan radially towards the center of the substrate for a length of 1 mm. Extract the contour data of this edge segment and record the maximum peak value of the adhesive layer thickness on the surface.

[0151] Remove the substrate and flip it over so that the back of the substrate is facing up, and then fix it back onto the stage of the industrial optical microscope with the graduated scale.

[0152] Adjust the microscope focus to the edge surface of the back of the substrate, look for the adhesive traces left by the adhesive curing over the sidewall along the outer circumference, and use measurement software to calibrate and record the maximum radial width of the adhesive spreading inward.

[0153] For each sample group, repeat the above thickness scanning and adhesive measurement operations at four mutually perpendicular radial positions: 0°, 90°, 180°, and 270°.

[0154] Table 4. Adhesive spread test data at the edges and back sides of Example 2 and Comparative Example 2.

[0155] Based on the data in Table 4 and Figure 4 The curve distribution shows that in Example 2, the peak thickness of the edge adhesive layer at the four test locations was between 0.03 μm and 0.08 μm, and the curing adhesive spread width on the back side was constant at 0 mm. In Comparative Example 2, the peak thickness of the edge adhesive layer was between 3.89 μm and 6.01 μm, and a cured adhesive layer distribution with a width of 0.28 mm to 0.52 mm was detected on the back side. Centrifugal force drove the liquid PDMS adhesive to undergo radial displacement from the center of the effective area of ​​the substrate to the periphery.

[0156] In Example 2, a 5mm wide annular membrane forms a physical flow-blocking surface. Liquid kinetic energy decays along this 5mm interval, eventually causing the fluid to stagnate and adhere within the membrane. In Comparative Example 2, a 1mm wide membrane was used, and the fluid kinetic energy failed to dissipate within this short distance. The undecayed adhesive crossed the outer boundary of the membrane and reached the outer edge of the substrate. Adhesive flowing through the sidewalls accumulated locally at the end-face junction due to surface tension, forming micron-thickness protrusions after curing.

[0157] Driven by its own gravity and capillary forces on the microscopic surface, the accumulated excess fluid moves along the outer wall to the back of the substrate and cross-links into a film. The 5mm width size limit controls the movement trajectory of the free adhesive. The trapped excess fluid is concentrated on the film carrier, eliminating edge accumulation and backing adhesion caused by crossing the boundary.

[0158] Test Example 5: High Temperature Resistance and Peel Performance Test

[0159] The substrate, which has been baked at 120°C and cooled to room temperature, is horizontally fixed on the vacuum testing platform of a microcomputer-controlled electronic tensile testing machine. The vacuum pump is turned on to ensure that the substrate does not slip.

[0160] Use a special wide-mouth clamp to clamp the protruding part of the annular film material that is exposed on the edge of the substrate. Adjust the height of the clamp and the stretching trajectory so that the angle between the stretching force direction and the substrate surface is 180°.

[0161] The tensile speed of the testing machine was set to 300 mm / min. The tensile program was started to conduct a continuous peel test on the annular film material. The system sensors collected the tensile load in real time and calculated and recorded the average peel force value during the stable peeling stage.

[0162] Observe and record the physical morphology of the membrane substrate layer after complete peeling, and record whether the membrane material is broken, partially torn, or remains intact.

[0163] After testing, the substrate was transferred to the stage of the optical surface contact angle measuring instrument. 2 μL of deionized water was dropped onto the surface of the original adhesive-free area of ​​the substrate edge. After the droplet stabilized, the contact angle value of the solid-liquid interface was measured and recorded.

[0164] Table 5. High-temperature peeling performance and surface energy test data of Example 2 and Comparative Example 3

[0165] According to Table 5 and Figure 5 The test data for Example 2 show that after baking at 120°C, the average peel force of the film was 170.5 N / m, and the average water contact angle of the degummed area was 62.9°. The average peel force for Comparative Example 3 was 1176.0 N / m, and the average water contact angle of the degummed area was 86.9°.

[0166] Figure 5 The column height distribution and scatter plot positions indicate that the interfacial peel strength of the two groups of samples differed by an order of magnitude under the same high-temperature thermal history. The acrylic adhesive layer used in Example 2 maintained a linear or weakly cross-linked polymer state at 120°C, and thermal motion did not induce chemical bonding with the sapphire substrate surface. The adhesion work of the adhesive interface after cooling was lower than the tensile yield strength of the polyethylene substrate layer, causing the film to fracture at the interface under tensile stresses ranging from 165.4 N / m to 182.7 N / m.

[0167] The contact angle data of 61.8° to 64.3° are consistent with the intrinsic surface energy of clean sapphire, confirming the absence of polymer residue on the substrate surface. In Comparative Example 3, the epoxy resin adhesive layer underwent a ring-opening polymerization reaction at 120°C, forming a three-dimensional network structure and establishing covalent bonds with the active hydroxyl groups on the sapphire surface. This chemical bonding caused the interfacial bonding force to exceed the physical load-bearing limit of the substrate. Under applied mechanical tensile conditions, stress concentration within the substrate layer led to structural fracture. The residual epoxy resin altered the local tension on the sapphire surface, causing the water contact angle to jump to over 83.7°. The application of the acrylic adhesive layer blocked the irreversible curing reaction at the interface caused by the high-temperature baking process, controlled the peeling threshold at the interface, and provided the material physical conditions required for the mechanical dry peeling process.

Claims

1. A method for preparing a substrate, characterized in that, Includes the following steps: A substrate material is provided, and the substrate material is cleaned and dried to obtain a pretreated substrate. A ring-shaped film material is provided, comprising a substrate layer and an adhesive layer, wherein the outer ring diameter of the ring-shaped film material is larger than the diameter of the pretreated substrate, and the inner ring diameter is smaller than the diameter of the pretreated substrate. The annular film is attached to the surface of the pretreated substrate through the adhesive layer to obtain a substrate covered with the film. An adhesive is applied to the surface of the substrate covered with the film material, so that the adhesive covers the central effective area of ​​the substrate and the surface of the annular film material, thereby obtaining a substrate with the adhesive coating on its surface. The substrate coated with adhesive is heated and baked to completely cure the adhesive and form an adhesive layer, resulting in a baked substrate. After the baked substrate cools to room temperature, pinch the protruding part of the outer ring of the annular film that is exposed at the edge of the substrate and slowly peel off the film. The adhesive layer attached to the film at the edge of the substrate is peeled off along with the film, leaving the intact cured adhesive layer in the effective area of ​​the substrate, thus completing the preparation of the substrate.

2. The preparation method according to claim 1, characterized in that, The specific operations for cleaning and drying the substrate material are as follows: The substrate material is placed in an ultrasonic cleaning tank, and a neutral detergent aqueous solution is used as the cleaning solution. Ultrasonic cleaning is performed at an ultrasonic frequency of 40-60kHz for 10-20 minutes. Then rinse with deionized water; Finally, place it in an oven and dry it at 60-80℃ for 20-30 minutes to obtain the pretreated substrate.

3. The preparation method according to claim 1, characterized in that, The specific operations for providing the annular membrane material include: A film material composed of a substrate layer with a thickness of 50-100μm and an adhesive layer with a thickness of 5-15μm is selected; The membrane material is cut into a circular ring structure using a laser cutting process to obtain the circular ring membrane material.

4. The preparation method according to claim 3, characterized in that, In the laser cutting process, the outer ring diameter of the annular film is cut to be 2-20 mm larger than the diameter of the substrate, and the ring width of the annular film is cut to be 2-10 mm.

5. The preparation method according to claim 3, characterized in that, The substrate layer is made of any one of polyethylene terephthalate, polyethylene, or polyvinyl chloride; The adhesive layer is an acrylic adhesive layer.

6. The preparation method according to claim 1, characterized in that, The process of attaching the annular film to the edge surface of the pretreated substrate is carried out in a Class 1000 cleanroom, with the ambient temperature controlled at 20-25°C and the relative humidity controlled at 40%-60%. Furthermore, after the application is completed, the film surface is pressed using a silicone roller.

7. The preparation method according to claim 1, characterized in that, The specific method for coating the substrate surface covered with film material at the edge with adhesive is as follows: A spin coater was used to perform spin coating on the substrate surface, with the spin coating speed controlled at 1000-5000 r / min and the spin coating time at 30-60 s.

8. The preparation method according to claim 1, characterized in that, The process parameters for heating and baking the substrate with the adhesive coating on its surface are as follows: The baking temperature is 80-150℃, and the baking time is 30-90 minutes.

9. The preparation method according to claim 1, characterized in that, The substrate material is a 4-8 inch circular glass sheet, sapphire sheet, or silicon wafer; the thickness of the substrate material is controlled to be 1.0-1.5 mm.

10. The preparation method according to claim 1, characterized in that, The coating adhesive is a photoresist or a polydimethylsiloxane adhesive.

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