A transparent polishing pad for photoelectrochemical mechanical polishing and a method of making and using the same

Abstract

This invention relates to a transparent polishing pad for photoelectrochemical mechanical polishing (PECMP), its preparation method, and its application method. The polishing pad is made of a highly transparent silicone matrix with ultraviolet light transmittance, and nano-silica abrasive particles are uniformly dispersed within the pad, giving it both excellent light transmission and stable mechanical polishing capabilities. This enables effective synergy of optical, electrical, chemical, and mechanical multi-energy fields in semiconductor PECMP processes. The transparent pad has excellent ultraviolet light transmittance, allowing ultraviolet light to penetrate the polishing pad during processing, achieving in-situ photochemical irradiation and chemical etching of the workpiece surface processing area, effectively improving the chemical reaction rate of the workpiece. Furthermore, the nano-silica abrasive particles dispersed in the transparent polishing pad maintain optical path continuity while providing stable mechanical cutting micro-actions. The transparent polishing pad with abrasive properties can achieve a dynamic balance of chemical and mechanical properties across the entire processing surface, effectively improving polishing efficiency and uniformity.

Description

Technical Field

[0001] This invention relates to the field of semiconductor ultra-precision machining technology, and more particularly to a transparent polishing pad for photoelectrochemical mechanical polishing, its preparation method, and its application method. Background Technology

[0002] Third-generation semiconductor materials, represented by silicon carbide (SiC) and gallium nitride (GaN), possess superior properties such as high frequency, high efficiency, high power, high voltage resistance, high temperature resistance, and strong radiation resistance due to their wide bandgap characteristics, playing an irreplaceable role in extreme applications. However, the extremely high hardness and brittleness of these materials also pose significant challenges to ultra-precision machining technology.

[0003] Chemical mechanical polishing (CMP) is currently the mainstream technology for achieving global planarization of semiconductor wafers. However, for third-generation semiconductor materials, traditional CMP technology has extremely low material removal rates, making it difficult to meet the needs of industrial production. Photoelectrochemical mechanical polishing (PECMP), as a composite polishing technology integrating light, electricity, chemistry, and mechanics, uses ultraviolet light to excite the generation of electron-hole pairs on the surface of semiconductor materials. Under the action of an electric field, their recombination is suppressed, causing the holes to oxidize the material surface and form a softening layer. This softening layer is then removed by the mechanical action of abrasive particles, achieving a processing effect of high removal rate and low damage.

[0004] However, a key technical bottleneck exists in existing PECMP technology: the opacity of the polishing pad. For example, Chinese patent application CN109648463A discloses a semiconductor wafer photoelectrochemical mechanical polishing method. To address the alternation of light and mechanical action, it designs regularly distributed through-holes on the polishing pad, applying photochemical action at the through-hole locations and mechanical action at the non-through-hole locations. However, this design has the following inherent drawbacks: First, ultraviolet light cannot continuously irradiate the workpiece surface in real time to induce photochemical oxidation reactions, but rather acts intermittently; second, ultraviolet light needs to be transmitted through the air medium, resulting in severe light intensity attenuation and inability to effectively induce photochemical reactions; third, the mechanical and photochemical actions are separated in time and space, and the oxide layer generated by the photochemical action cannot be removed by the mechanical action in time, which to some extent limits the continuous chemical action, resulting in unsatisfactory final processing efficiency.

[0005] Therefore, developing a polishing pad that can simultaneously achieve efficient ultraviolet light transmission and stable mechanical removal, and realize in-situ synergy between photochemical and mechanical effects, has become the key to improving the processing efficiency of PECMP technology. Summary of the Invention

[0006] To address the aforementioned technical problems, a transparent polishing pad for photoelectrochemical-mechanical polishing is provided, along with its preparation and application methods. Through the synergy of material design and structural optimization, the technical problem that the opacity of existing polishing pads prevents the simultaneous and in-situ synergistic interaction of photochemical and mechanical processes is solved.

[0007] The technical means employed in this invention are as follows:

[0008] A transparent polishing pad for photoelectrochemical mechanical polishing includes a stacked arrangement of: A transparent substrate layer is composed of a cured material containing optical-grade liquid silicone rubber and uniformly dispersed SiO2 abrasive. Rigid polysilsesquioxane nanoparticles are introduced into the polysiloxane backbone of the optical-grade liquid silicone rubber through chemical bonding. A microstructure layer, located on one side surface of the transparent substrate layer, includes a microgroove array with a preset pattern; An adhesive-backed composite layer is laminated to the transparent substrate layer on the side away from the microstructure layer.

[0009] Furthermore, the rigid polysilsesquioxane nanoparticles have a mass percentage of 3wt% to 8wt% in the transparent matrix layer.

[0010] Furthermore, the optical-grade liquid silicone rubber has a transmittance of more than 90% in the ultraviolet light band with a wavelength of 365nm to 405nm.

[0011] Furthermore, the particle size of the SiO2 abrasive is from 10 nm to 1000 nm, and its mass percentage in the transparent substrate layer is from 1 wt% to 30 wt%.

[0012] Furthermore, the trench depth of the microgroove array is 10μm to 500μm, the trench width is 20μm to 2000μm, the center distance between adjacent trenches is 5mm to 10mm, and the cross-sectional shape of the trench is one of rectangle, trapezoid or V-shape.

[0013] On the other hand, the present invention also discloses a method for preparing the above-mentioned transparent polishing pad, comprising the following steps: S1: Raw material pretreatment, optical grade liquid silicone rubber, hydrogen-containing crosslinking agent and inhibitor are filtered through micron-level precision filters and vacuum degassing treatment to remove dissolved gases; S2: Abrasive dispersion and mixing: Under the protection of dry inert gas, pretreated optical-grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles, SiO2 abrasive, hydrogen-containing crosslinking agent and inhibitor are mixed in a preset ratio to obtain a mixed system. S3: Mold filling and curing: The mixed system is vacuum-injected into the mold, first subjected to low-temperature gelation treatment at 20°C to 60°C for 5 to 30 minutes, and then subjected to post-curing treatment at 100°C to 150°C for 30 minutes to 2 hours to obtain a transparent polishing pad blank. S4: Surface microstructure processing, a microgroove array with a preset pattern is processed on one side surface of the transparent polishing pad blank; S5: Adhesive backing bonding, a pressure-sensitive adhesive layer is bonded to the other side surface of the transparent polishing pad blank to obtain the transparent polishing pad.

[0014] Furthermore, the pore size of the micron-level precision filter in step S1 is 0.5μm to 5μm, the vacuum degree of the vacuum degassing is not lower than -0.095MPa, and the degassing time is 20 minutes to 40 minutes.

[0015] Furthermore, the mixing in step S2 is carried out in steps: first, optical grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles and SiO2 abrasive are initially mixed at low speed, and then hydrogen-containing crosslinking agent and inhibitor are added for vacuum planetary stirring. The vacuum degree of the vacuum planetary stirring is not lower than -0.09MPa, the stirring speed is 500rpm to 2000rpm, and the stirring time is 3 minutes to 10 minutes. The viscosity of the mixture in step S2 is controlled within the range of 500 cps to 5000 cps.

[0016] Furthermore, the microgroove array described in step S4 is processed by one of CNC milling, laser etching, or precision molding.

[0017] On the other hand, the present invention also discloses a semiconductor photoelectrochemical mechanical polishing method, using the aforementioned transparent polishing pad, comprising the following steps: The transparent polishing pad is mounted on the polishing disc with the microstructure layer of the transparent polishing pad facing upwards; The wafer to be polished is brought into contact with the surface of the microstructure layer of the transparent polishing pad, and polishing pressure is applied. During the polishing process, ultraviolet light is applied to the contact interface between the transparent polishing pad and the wafer to be polished. The ultraviolet light penetrates the transparent substrate layer of the transparent polishing pad and excites a photochemical reaction on the surface of the wafer to be polished. Simultaneously, the transparent polishing pad rotates with the polishing disc, and the microgroove array delivers polishing fluid. The SiO2 abrasive, uniformly dispersed in the transparent substrate layer, mechanically removes the material softened by the photochemical reaction.

[0018] Compared with the prior art, the present invention has the following advantages: 1. This invention introduces rigid polysilsesquioxane nanoparticles through chemical bonding into the polysiloxane backbone of optical-grade liquid silicone rubber, significantly improving the thermal stability and mechanical strength of the pad without substantially sacrificing the material's ultraviolet light transmittance (>90%). This material design resolves the technical contradiction of traditional transparent materials struggling to balance high transmittance and good mechanical properties, providing a material basis for in-situ synergy between photochemical and mechanical effects.

[0019] 2. This invention pre-disperses and composites SiO2 abrasive within a transparent substrate, rather than simply coating it onto the surface. This embedded design ensures that as the pad surface gradually wears down during polishing, new abrasive continuously emerges, maintaining a stable material removal rate. More importantly, the abrasive and the light transmission path coexist in the same transparent medium, achieving complete spatial overlap and temporal synchronization between ultraviolet light excitation and mechanical removal. This fundamentally solves the defect in existing technologies where photochemical and mechanical actions alternate and cannot coordinate.

[0020] 3. The preparation method of this invention employs a stepwise curing process of low-temperature gelation followed by high-temperature post-curing. The low-temperature gelation stage initiates cross-linking of the system and significantly increases its viscosity, thereby locking in its shape and effectively suppressing the sedimentation of high-density SiO2 abrasive during the curing process, ensuring the uniform distribution of the abrasive throughout the transparent matrix layer. The high-temperature post-curing stage ensures complete cross-linking reaction, resulting in stable mechanical properties. This process design is crucial for ensuring batch consistency and polishing uniformity of the polishing pads.

[0021] 4. This invention fabricates a micro-groove array with specific depth, width, and spacing on the surface of a transparent substrate layer. These micro-grooves act as channels for delivering polishing slurry and removing grinding debris during the polishing process, ensuring that fresh polishing slurry can continuously enter the processing area while promptly removing reaction products. This avoids secondary scratches on the wafer surface caused by grinding debris, further improving polishing quality and efficiency.

[0022] 5. In the preparation method of this invention, the raw material pretreatment adopts micron-level filtration and vacuum degassing, the mixing process is carried out under the protection of dry inert gas, vacuum injection into the mold, and thorough cleaning after processing. This series of cleaning process measures effectively prevents the introduction of impurities, bubbles and moisture, ensuring that the polishing pad is defect-free and has a high surface finish, thereby ensuring the effective transmission of ultraviolet light and the stability of polishing.

[0023] In summary, the polishing pad of this invention is made of a highly transparent silicone matrix with ultraviolet light transmittance, and uniformly disperses nano-silica abrasive particles inside the polishing pad. This gives it both excellent light transmission capability and stable mechanical polishing capability, enabling effective synergy of optical, electrical, chemical, and mechanical multi-energy fields in semiconductor PECMP processes. The transparent pad has excellent ultraviolet light transmittance, allowing ultraviolet light to penetrate the polishing pad during processing, achieving in-situ photochemical irradiation and chemical corrosion of the workpiece surface processing area, effectively improving the chemical reaction rate of the workpiece. Furthermore, the nano-silica abrasive particles dispersed in the transparent polishing pad maintain optical path continuity while providing stable mechanical cutting micro-actions. The transparent polishing pad with abrasive properties can achieve a dynamic balance of chemical and mechanical properties across the entire processing surface, effectively improving polishing efficiency and uniformity, ultimately achieving ultra-smooth, flattened, and highly efficient processing of the workpiece. The transparent polishing pad obtained by the above preparation method has high ultraviolet transmittance, stable mechanical polishing ability and optimized surface microstructure. It can effectively improve the oxidation efficiency, polishing uniformity and processing stability in photoelectrochemical mechanical polishing process, and is suitable for ultra-precision surface processing of third-generation semiconductor materials such as silicon carbide and gallium nitride. Attached Figure Description

[0024] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the preparation process of the transparent polishing pad of the present invention.

[0026] Figure 2 This is a schematic diagram illustrating the polishing principle of the transparent polishing pad of the present invention.

[0027] Figure 3 This is a schematic diagram of the transparent polishing pad of the present invention.

[0028] In the diagram: 1. Wafer; 2. Transparent polishing pad; 3. Pressure-sensitive adhesive; 4. Polishing disc; 5. Polymer crosslinking agent; 6. SiO2. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0033] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0034] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0035] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0036] like Figures 1-3 As shown, this embodiment of the invention discloses a transparent polishing pad for photoelectrochemical mechanical polishing, comprising: A transparent substrate layer is composed of a cured material containing optical-grade liquid silicone rubber and uniformly dispersed SiO2 abrasive. Rigid polysilsesquioxane nanoparticles are introduced into the polysiloxane backbone of the optical-grade liquid silicone rubber through chemical bonding. A microstructure layer, located on one side surface of the transparent substrate layer, includes a microgroove array with a preset pattern; An adhesive-backed composite layer is laminated to the transparent substrate layer on the side away from the microstructure layer.

[0037] Furthermore, the rigid polysilsesquioxane nanoparticles have a mass percentage of 3wt% to 8wt% in the transparent matrix layer.

[0038] Furthermore, the optical-grade liquid silicone rubber has a transmittance of more than 90% in the ultraviolet light band with a wavelength of 365nm to 405nm.

[0039] Furthermore, the particle size of the SiO2 abrasive is from 10 nm to 1000 nm, and its mass percentage in the transparent substrate layer is from 1 wt% to 30 wt%.

[0040] Furthermore, the trench depth of the microgroove array is 10μm to 500μm, the trench width is 20μm to 2000μm, the center distance between adjacent trenches is 5mm to 10mm, and the cross-sectional shape of the trench is one of rectangle, trapezoid or V-shape.

[0041] On the other hand, the present invention also discloses a method for preparing the above-mentioned transparent polishing pad, comprising the following steps: S1: Raw material pretreatment will use optical-grade liquid silicone rubber with high transmittance to ultraviolet light. Its low viscosity is conducive to degassing. Hydrogen-containing crosslinking agents and inhibitors will be filtered through micron-level precision filters and vacuum degassing treatment to remove dissolved gases. A small amount (3wt%-8wt%) of rigid polysilsesquioxane nanoparticles will be introduced into the polysiloxane backbone through chemical bonding, which can significantly improve thermal stability and mechanical properties, while hardly affecting its optical transparency.

[0042] S2: Abrasive dispersion and mixing: Under dry inert gas protection, pretreated optical-grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles, SiO2 abrasive, hydrogen-containing crosslinking agent, and inhibitor are mixed in a preset ratio to obtain a mixed system. Specifically, a planetary mixer is used for medium-speed mixing under controlled vacuum to ensure uniformity without excessive air entrainment. First, the optical-grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles, and SiO2 abrasive are initially mixed, and then the hydrogen-containing crosslinking agent and inhibitor are added for vacuum planetary mixing. S3: Use high-gloss quartz glass or mirror-polished metal molds and apply a release agent to ensure a smooth surface after curing. Vacuum inject the mixture into the mold, first perform a low-temperature gelation treatment at 20°C to 60°C for 5 to 30 minutes to allow initial cross-linking, and then perform a post-curing treatment at 100°C to 150°C for 30 minutes to 2 hours to ensure complete cross-linking reaction, resulting in a transparent polishing pad blank; S4: Surface microstructure processing, a microgroove array with a preset pattern is processed on one side surface of the transparent polishing pad blank; S5: Adhesive backing bonding, a pressure-sensitive adhesive 3 adhesion layer is bonded to the other side surface of the transparent polishing pad blank to obtain the transparent polishing pad.

[0043] Furthermore, the pore size of the micron-level precision filter in step S1 is 0.5μm to 5μm, the vacuum degree of the vacuum degassing is not lower than -0.095MPa, and the degassing time is 20 minutes to 40 minutes.

[0044] Furthermore, the mixing in step S2 is carried out in steps: first, optical grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles and SiO2 abrasive are initially mixed at low speed, and then hydrogen-containing crosslinking agent and inhibitor are added for vacuum planetary stirring. The vacuum degree of the vacuum planetary stirring is not lower than -0.09MPa, the stirring speed is 500rpm to 2000rpm, and the stirring time is 3 minutes to 10 minutes. After mixing, the viscosity of the system is monitored using a viscometer. The viscosity of the mixed system described in step S2 is controlled within the range of 500 cps to 5000 cps.

[0045] Furthermore, the microgroove array described in step S4 is manufactured using one of the following methods: CNC milling, laser etching, or precision molding. The manufacturing process must ensure that the groove edges are clear and burr-free. After manufacturing, the surface of the pad and the debris within the grooves are thoroughly cleaned with a lint-free cloth and a low-residue solvent.

[0046] The transparent polishing pads were tested for properties such as transmittance, hardness, and elastic modulus. A UV-Vis spectrophotometer was used to measure the transmittance of the polishing pads in the target UV band, ensuring that the transmittance was >90%. The hardness, elastic modulus, and compression resilience of the polishing pads were also tested. The geometric dimensions and surface roughness of the grooves were measured using a white light interferometer or a laser confocal microscope.

[0047] On the other hand, the present invention also discloses a semiconductor photoelectrochemical mechanical polishing method, using the aforementioned transparent polishing pad, comprising the following steps: The transparent polishing pad is mounted on the polishing disc with the microstructure layer of the transparent polishing pad facing upwards; The wafer 1 to be polished is brought into contact with the surface of the microstructure layer of the transparent polishing pad 2, and polishing pressure is applied. During the polishing process, ultraviolet light is applied to the contact interface between the transparent polishing pad and the wafer to be polished. The ultraviolet light penetrates the transparent substrate layer of the transparent polishing pad and excites a photochemical reaction on the surface of the wafer to be polished. Simultaneously, the transparent polishing pad rotates with the polishing disc 4, and the microgroove array delivers polishing liquid. The SiO2 abrasive, uniformly dispersed in the transparent substrate layer, mechanically removes the material softened by the photochemical reaction.

[0048] Example 1 This embodiment provides a transparent polishing pad suitable for polishing general-purpose semiconductor materials, with the following formulation: Optical grade addition-curing liquid silicone rubber (matrix): LSR7000 series high transparency liquid silicone rubber produced by Momentive Performance Materials, 100 parts by weight, with a transmittance of 94% at 365nm wavelength (this series of products can achieve a transmittance of up to 98% in the visible and near-ultraviolet bands, and a measured transmittance of >90% in the 365nm ultraviolet band); Rigid polysilsesquioxane nanoparticles (modifier): 3 parts by weight, introduced into the silicone rubber backbone through chemical bonding; Hydrogen-containing silicone oil crosslinking agent: 0.5 parts by weight, added at a molar ratio of Si-H to vinyl groups in silicone rubber of 1.2:1; Inhibitor: Ethynyl cyclohexanol, 0.05 parts by weight; SiO2 abrasive: average particle size 100nm, 100 parts by weight.

[0049] The specific preparation steps are as follows: S1: Raw material pretreatment. Optical-grade liquid silicone rubber with high transmittance to ultraviolet light will be selected. Its low viscosity is conducive to degassing. Hydrogen-containing crosslinking agents and inhibitors will be filtered through micron-level precision filters and subjected to vacuum degassing treatment to remove dissolved gases. The rigid polysilsesquioxane nanoparticles are chemically bonded into the polysiloxane backbone via hydrosilylation. Specifically, cage-like polysilsesquioxanes (POSS) containing active functional groups (such as vinyl or silanol groups) are used as modifiers. Under the action of a platinum catalyst, the active functional groups on the POSS undergo hydrosilylation reactions with the alkenyl groups (such as vinyl groups) in the liquid silicone rubber base polymer or the silanol groups in the crosslinking agent, forming covalent bonds. This allows the POSS nanoparticles to be chemically bonded into the crosslinked network of the silicone rubber. This chemical bonding method ensures the uniform dispersion and long-term stability of the POSS nanoparticles in the matrix, while enhancing the mechanical properties of the matrix through the rigid cage structure of the POSS without affecting its optical transmittance.

[0050] S2: Abrasive Dispersion and Mixing. Under a dry nitrogen atmosphere, weigh out the components according to the above formula and add them to a planetary mixing jar. First, add the liquid silicone rubber, rigid polysilsesquioxane nanoparticles, and SiO2 abrasive, and manually mix at a low speed of 300 rpm for 3 minutes to initially wet the powder. Then add the hydrogen-containing crosslinking agent, catalyst, and inhibitor. Place the mixing jar in a planetary mixer, turn on the vacuum pump to achieve a vacuum of -0.095 MPa inside the jar, mix at 800 rpm for 3 minutes, and then mix at 1200 rpm for 5 minutes. After mixing, sample the system viscosity and measure it to be 850 mPa·s.

[0051] S3: Mold Filling and Curing. A mirror-finish stainless steel mold with a hard chromium plating and a fluorine-based release agent is used. The mixture is injected into the mold using a vacuum injection molding machine, ensuring no air bubbles are trapped. The mold is placed in a low-temperature oven at 20°C for 30 minutes for low-temperature gelation treatment, allowing the system to initially cross-link and form a gel state, locking the shape and preventing abrasive sedimentation. Subsequently, the mold is transferred to a high-temperature oven for post-curing: held at 100°C for 2 hours to ensure complete cross-linking. After natural cooling to room temperature, the mold is demolded to obtain a transparent polishing pad blank.

[0052] S4: Surface microstructure processing. For example... Figure 3 As shown, a grid-like microgroove array was fabricated on one side surface of a transparent polishing pad blank using a precision laser etching machine. The grooves were 100 μm deep, 500 μm wide, and 5 mm apart, with a rectangular cross-section. After fabrication, the surface and grooves were ultrasonically cleaned sequentially with ultrapure water and isopropanol for 15 minutes, and then wiped dry with a lint-free cloth to remove debris and residue from the surface and the grooves.

[0053] S5: Adhesive backing lamination. A pressure-sensitive adhesive layer with a thickness of 0.1mm is bonded to the smooth surface on the other side of the transparent polishing pad blank, ensuring that the surface is flat and free of air bubbles after bonding, thus obtaining the final transparent polishing pad.

[0054] Example 2 This embodiment provides a transparent polishing pad with the following formula: Optical grade addition-curing liquid silicone rubber (Momentive LSR7000 series): 100 parts by weight, with a transmittance of 91% at 365nm wavelength; Rigid polysilsesquioxane nanoparticles (epoxy group modified): 5 parts by weight; Hydrogen-containing silicone oil crosslinking agent: 0.8 parts by weight, added at a molar ratio of Si-H to vinyl groups in silicone rubber of 1.3:1; Inhibitor: 3-methyl-1-butyn-3-ol (methylbutynol), 0.06 parts by weight; SiO2 abrasive: average particle size 200nm, 20 parts by weight.

[0055] The specific preparation steps are as follows: S1: Raw material pretreatment. Liquid silicone rubber, hydrogen-containing crosslinking agent, and inhibitor were filtered through a 2μm PTFE filter. Subsequently, each component was placed in a vacuum degassing machine and degassed for 25 minutes under a vacuum of -0.096MPa.

[0056] S2: Abrasive Dispersion and Mixing. Under dry nitrogen protection, weigh each component according to the formula. First, add the liquid silicone rubber, POSS, and SiO2 abrasive, and mix at a low speed of 400 rpm for 2 minutes. Then add the crosslinking agent, catalyst, and inhibitor. Under a vacuum of -0.092 MPa, mix at 1000 rpm for 2 minutes, and then at 1500 rpm for 4 minutes. The viscosity after mixing was measured to be 1850 mPa·s.

[0057] S3: Mold filling and curing. A quartz glass mold is used, coated with a fluorine-based release agent. The mixture is vacuum-injected into the mold. It is first gelled at 35°C for 20 minutes, then post-cured at 120°C for 1.5 hours.

[0058] S4: Surface microstructure machining. Grooves were machined using CNC milling, with a depth of 300 μm, a width of 1000 μm, a center distance of 8 mm, and a trapezoidal cross-section. The cleaning steps were the same as in Example 1.

[0059] S5: Adhesive-backed lamination. Same as Example 1.

[0060] Example 3 This embodiment provides a transparent polishing pad with the following formula: Optical grade addition-curing liquid silicone rubber (Momentive LSR7000 series): 100 parts by weight, with a transmittance of 89% at 365nm wavelength; Rigid polysilsesquioxane nanoparticles: 7 parts by weight; Hydrogen-containing silicone oil crosslinking agent: 1.0 parts by weight, added at a Si-H to vinyl molar ratio of 1.4:1; Inhibitor: 1-ethynyl-1-cyclohexanol, 0.08 parts by weight; SiO2 abrasive: 30 parts by weight, average particle size 500nm.

[0061] 100 parts by weight of SiO2 abrasive with an average particle size of 200 nm; Preparation steps: S1: Raw material pretreatment. Filter pore size 5μm, vacuum degassing at -0.095MPa for 30 minutes.

[0062] S2: Abrasive dispersion and mixing. Low-speed mixing at 500 rpm for 2 minutes; vacuum planetary stirring: vacuum degree -0.09 MPa, first mixing at 1200 rpm for 3 minutes, then mixing at 1800 rpm for 4 minutes. The measured viscosity was 3350 mPa·s.

[0063] S3: Mold filling and curing. Mirror-finish stainless steel mold is used. Gelation conditions: 50℃, 15 minutes. Post-curing: 140℃ for 1 hour.

[0064] S4: Surface microstructure processing. Grooves are formed using a precision molding process, with a depth of 500 μm, a width of 2000 μm, a center-to-center distance of 10 mm, and a rectangular cross-section. The cleaning steps are the same as in Example 1.

[0065] S5: Adhesive-backed lamination. Same as Example 1.

[0066] Example 4 This embodiment provides a transparent polishing pad with the following formula: Optical grade addition-curing liquid silicone rubber (Momentive LSR7000 series): 100 parts by weight, with a transmittance of 92% at 365nm wavelength; Rigid polysilsesquioxane nanoparticles: 8 parts by weight; Hydrogen-containing silicone oil crosslinking agent: 0.6 parts by weight, added at a Si-H to vinyl molar ratio of 1.2:1; Inhibitor: 2-methyl-3-butyn-2-ol, 0.05 parts by weight; SiO2 abrasive: 15 parts by weight, average particle size 100nm.

[0067] Preparation steps: S1: Raw material pretreatment. Filter pore size 1μm, vacuum degassing at -0.097MPa for 22 minutes.

[0068] S2: Abrasive dispersion and mixing. Low-speed mixing at 350 rpm for 3 minutes; vacuum planetary stirring: vacuum degree -0.093 MPa, first mixing at 900 rpm for 3 minutes, then mixing at 1400 rpm for 5 minutes. The measured viscosity was 1260 mPa·s.

[0069] S3: Mold filling and curing. Quartz glass mold is used. Gelation conditions: 25℃, 25 minutes. Post-curing: 110℃ for 1.8 hours.

[0070] S4: Surface microstructure processing. Grooves were created using laser etching, with a depth of 200 μm, a width of 800 μm, a center-to-center distance of 6 mm, and a V-shaped cross-section. The cleaning steps were the same as in Example 1.

[0071] S5: Adhesive-backed lamination. Same as Example 1.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A transparent polishing pad for photoelectrochemical mechanical polishing, characterized in that, Including cascading settings: A transparent substrate layer is composed of a cured material containing optical-grade liquid silicone rubber and uniformly dispersed SiO2 abrasive. Rigid polysilsesquioxane nanoparticles are introduced into the polysiloxane backbone of the optical-grade liquid silicone rubber through chemical bonding. A microstructure layer, located on one side surface of the transparent substrate layer, includes a microgroove array with a preset pattern; An adhesive-backed composite layer is laminated to the transparent substrate layer on the side away from the microstructure layer.

2. The transparent polishing pad for photoelectrochemical mechanical polishing according to claim 1, characterized in that, The rigid polysilsesquioxane nanoparticles have a mass percentage of 3wt% to 8wt% in the transparent matrix layer.

3. The transparent polishing pad for photoelectrochemical mechanical polishing according to claim 1, characterized in that, The optical-grade liquid silicone rubber has a transmittance of more than 90% in the ultraviolet light band with a wavelength of 365nm to 405nm.

4. The transparent polishing pad for photoelectrochemical mechanical polishing according to claim 1, characterized in that, The SiO2 abrasive has a particle size of 10 nm to 1000 nm and its mass percentage in the transparent substrate layer is 1 wt% to 30 wt%.

5. The transparent polishing pad for photoelectrochemical mechanical polishing according to claim 1, characterized in that, The microgroove array has a groove depth of 10μm to 500μm, a groove width of 20μm to 2000μm, a center distance between adjacent grooves of 5mm to 10mm, and a cross-sectional shape of the grooves that is rectangular, trapezoidal, or V-shaped.

6. A method for preparing a transparent polishing pad for photoelectrochemical mechanical polishing as described in any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Raw material pretreatment, optical grade liquid silicone rubber, hydrogen-containing crosslinking agent and inhibitor are filtered through micron-level precision filters and vacuum degassing treatment to remove dissolved gases; S2: Abrasive dispersion and mixing: Under the protection of dry inert gas, pretreated optical-grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles, SiO2 abrasive, hydrogen-containing crosslinking agent and inhibitor are mixed in a preset ratio to obtain a mixed system. S3: Mold filling and curing: The mixed system is vacuum-injected into the mold, first subjected to low-temperature gelation treatment at 20°C to 60°C for 5 to 30 minutes, and then subjected to post-curing treatment at 100°C to 150°C for 30 minutes to 2 hours to obtain a transparent polishing pad blank. S4: Surface microstructure processing, a microgroove array with a preset pattern is processed on one side surface of the transparent polishing pad blank; S5: Adhesive backing bonding, a pressure-sensitive adhesive layer is bonded to the other side surface of the transparent polishing pad blank to obtain the transparent polishing pad.

7. The method according to claim 6, characterized in that, The micron-level precision filter in step S1 has a pore size of 0.5μm to 5μm, the vacuum degree of the vacuum degassing is not lower than -0.095MPa, and the degassing time is 20 minutes to 40 minutes.

8. The method according to claim 6, characterized in that, The mixing in step S2 is carried out in steps: first, optical grade liquid silicone rubber, rigid polysilsesquioxane nanoparticles and SiO2 abrasive are initially mixed at low speed, and then hydrogen-containing crosslinking agent and inhibitor are added for vacuum planetary stirring. The vacuum degree of the vacuum planetary stirring is not lower than -0.09MPa, the stirring speed is 500rpm to 2000rpm, and the stirring time is 3 minutes to 10 minutes. The viscosity of the mixture in step S2 is controlled within the range of 500 cps to 5000 cps.

9. The method according to claim 6, characterized in that, The microgroove array described in step S4 is processed by one of CNC milling, laser etching, or precision molding.

10. A semiconductor photoelectrochemical mechanical polishing method, using the transparent polishing pad according to any one of claims 1 to 5, characterized in that, Includes the following steps: The transparent polishing pad is mounted on the polishing disc with the microstructure layer of the transparent polishing pad facing upwards; The wafer to be polished is brought into contact with the surface of the microstructure layer of the transparent polishing pad, and polishing pressure is applied. During the polishing process, ultraviolet light is applied to the contact interface between the transparent polishing pad and the wafer to be polished. The ultraviolet light penetrates the transparent substrate layer of the transparent polishing pad and excites a photochemical reaction on the surface of the wafer to be polished. Simultaneously, the transparent polishing pad rotates with the polishing disc, and the microgroove array delivers polishing fluid. The SiO2 abrasive, uniformly dispersed in the transparent substrate layer, mechanically removes the material softened by the photochemical reaction.

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