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CN-121989158-A - Triboelectric enhanced substrate chemical mechanical polishing method

CN121989158ACN 121989158 ACN121989158 ACN 121989158ACN-121989158-A

Abstract

A triboelectric enhancement substrate chemical mechanical polishing method belongs to the field of chemical mechanical polishing of materials. In a conventional polishing solution system, dielectric materials with different electronegativity are added to form a uniform dispersion system, and high-frequency friction is generated among polishing material particles and between the polishing particles and the surface of a SiC wafer in the polishing process to generate friction charges, so that active oxygen species (such as OH) are generated in a large amount, the oxidation rate of the SiC surface is enhanced, and the removal rate of the polishing material is further improved. The method can be used on materials such as silicon carbide, gallium nitride, silicon wafer, sapphire and the like.

Inventors

  • HAN CHANGBAO
  • HAO MINGYANG
  • CHANG LIHONG
  • ZHAO WENKANG

Assignees

  • 北京工业大学

Dates

Publication Date
20260508
Application Date
20251231

Claims (10)

  1. 1. A method for enhancing chemical mechanical polishing of a substrate based on frictional charge is characterized in that dielectric material particles with electronegativity are added into a conventional polishing solution system containing polishing abrasive particles to form a uniform dispersion system, and the electronegative dielectric material particles and the polishing abrasive particles generate high-frequency friction with the surface of the substrate in the polishing process to generate frictional charge, so that active oxygen species are generated in a large amount, the reaction rate of the substrate material is enhanced, and the removal rate of the substrate surface material is improved; the electronegative dielectric material particles are polymer particles with negative friction electric polarity, the surface of the dielectric material is negatively charged when the dielectric material rubs with the polished substrate material or polishing abrasive particles, and the surface of the polished substrate material is positively charged.
  2. 2. The method of claim 1, wherein the polishing slurry after the addition of the dielectric particles comprises particles of an electronegative dielectric material, particles of a polishing abrasive, an oxidizing agent, a dispersing agent, a pH adjustor, and a solvent, and wherein the dielectric particles of the dielectric material have a dielectric constant less than the polishing abrasive particles and the substrate material.
  3. 3. The method according to claim 2, wherein the electronegative dielectric material is selected from one or more of Polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), fluorinated ethylene propylene copolymer (FEP), polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), poly Chlorotrifluoroethylene (PCTFE) and the like, and has an average particle size of 0.01-500 μm, and is added in an amount of 0.01-20 wt%, preferably 0.01-10 wt%, more preferably 0.1-5 wt% of the total mass of the polishing liquid.
  4. 4. The method according to claim 2, wherein the polishing abrasive particles are one or more of rare earth oxide, manganese oxide, silicon oxide, and aluminum oxide, and the polishing powder has a particle size of 10 to 1000 nm and a content of 0.1 to 30 wt%, preferably 0.1 to 15 wt%, more preferably 0.5 to 10 wt% of the total mass of the polishing liquid.
  5. 5. The method according to claim 2, wherein the oxidizing agent is one or more of potassium permanganate, hydrogen peroxide, persulfates, permanganic acid, hypochlorite, and the oxidizing agent is 0.05-10 wt%, preferably 0.05-5 wt%, more preferably 0.1-5 wt% of the total mass of the polishing liquid.
  6. 6. The method of claim 2, wherein the dispersant comprises polyethylene glycol, polyethylene glycol monolaurate, polyethylene glycol monostearate, polyethylene glycol distearate, polyethylene glycol monooleate, polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, ammonium polyacrylate, sodium hexametaphosphate, ammonium citrate, sodium dodecylbenzenesulfonate, sodium dodecylsulfate, triethanolamine dodecylsulfate, ammonium dodecylsulfate, dodecyl betaine, octadecylamine acetate, octadecylbetaine, 2-hydroxyethyl methacrylate, polymethacrylate, carboxymethyl cellulose, potassium carboxymethyl cellulose, sodium carboxymethyl cellulose, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene oleyl ether, polyoxyethylene higher alcohol ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, polyoxyalkylene alkyl ether, polyoxyethylene derivatives, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitol tetraoleate, polyoxyethylene castor oil, polyoxyethylene alkyl amine hardened, polyoxyethylene lauryl amine, or a mixture of more than one or more of said dispersants of 5% by weight, 0% by weight, based on the total weight of the total of the dispersant and 0.01% to more of the total weight of the dispersant.
  7. 7. The method according to claim 2, wherein the pH regulator is one or more of nitric acid, hydrochloric acid, sulfuric acid, hydrofluoric acid, potassium hydroxide and sodium hydroxide, and the pH value is adjusted to be 1.5-12 according to the need; The solvent is deionized water or other solvent insoluble in the solution forming the dispersion.
  8. 8. The method according to claim 1, wherein the preparation of the polishing liquid comprises the steps of (1) preparing an electronegative dielectric material dispersion liquid by weighing a required amount of electronegative dielectric material particles, adding a certain amount of deionized water or other solvents, and dispersing by ultrasonic waves, stirring and the like to obtain a stable dispersion liquid; (2) Preparing a basic polishing solution, namely weighing a certain amount of polishing abrasive particles, an oxidant and a dispersing agent, adding the polishing abrasive particles, the oxidant and the dispersing agent into deionized water or other solvents, uniformly stirring, and regulating the pH value to a target value by using a pH regulator; (3) And (3) ultrasonically mixing the electronegative dielectric material dispersion liquid prepared in the step (1) with the basic polishing liquid prepared in the step (2), and uniformly stirring.
  9. 9. The method according to claim 1, wherein the polishing method comprises the steps of uniformly stirring the prepared polishing liquid, polishing, namely arranging a polishing pad on a polishing disc, dripping the polishing liquid on the polishing pad, placing a substrate sheet to be polished on the polishing pad, placing a carrier or a pressing block above the substrate sheet for exerting pressure, enabling the polishing disc to drive the polishing pad to rotate, setting the polishing pressure to be 2-10 psi, enabling the rotation speed of the polishing disc to be 40-300 rpm, continuously polishing 20-90 min, removing the substrate sheet after polishing, and detecting the removal rate and the surface roughness of the surface material of the substrate sheet after polishing.
  10. 10. The method of claim 1, wherein the substrate is selected from the group consisting of silicon carbide, gallium nitride, silicon wafers (single crystal silicon, polycrystalline silicon, etc.), sapphire, diamond, carbonaceous materials, flat glass, optical glass, liquid crystal display glass, and the like.

Description

Triboelectric enhanced substrate chemical mechanical polishing method Technical Field The invention belongs to the technical field of material processing, in particular relates to a Chemical Mechanical Polishing (CMP) method of a material, and particularly relates to a Polishing technology for improving the removal rate of a Polishing material by utilizing surface oxidation of a friction charge reinforced material. Background The substrate, especially silicon carbide (SiC), is used as a third generation wide bandgap semiconductor material, has excellent performances of high breakdown electric field strength, high thermal conductivity, high electron saturation drift rate and the like, and has wide application prospects in the fields of power electronic devices, radio frequency devices, new energy automobiles, artificial intelligence and the like. However, siC has a mohs hardness as high as 9.5, inferior to diamond (10 mohs hardness), and is extremely chemically stable, which presents a great challenge for ultra-precise processing of wafers. Currently, the polishing of SiC wafers mainly adopts the following technical routes: (1) Mechanical polishing, namely, adopting nano-or micron-sized particles such as nano-sized SiO 2 or Al 2O3 as polishing abrasive, wherein the system mainly relies on the mechanical friction action of SiO 2 or Al 2O3 particles and the SiC surface to realize material removal, and the polishing material removal rate is generally lower due to the lack of an effective oxidation enhancement mechanism only by the mechanical grinding action of the particles and the SiC. (2) And (3) chemical mechanical polishing, namely taking rare earth oxides such as CeO 2、La2O3 and the like as polishing abrasive materials and matching with strong oxidants such as KMnO 4、H2O2、K2S2O8 and the like. The core mechanism of the system is that an oxidant forms a soft SiO 2 oxide layer on the surface of SiC first, then rare earth oxide abrasive removes the oxide layer through mechanical grinding, ceO 2 can cooperate with the oxidant to promote the oxidation of the surface of SiC due to the Ce 3+/Ce4+ redox cycle characteristic. (3) And the chemical mechanical polishing is assisted, namely the anodic oxidation of the SiC surface is promoted by an external electric field or an external optical field, and the oxidation rate can be obviously improved theoretically. However, the method has the problems of complex structure, difficult process implementation and oxidation uniformity. Aiming at the current polishing method of the SiC wafer, the following problems are mainly faced: (1) For mechanical polishing, due to the high hardness of SiC, the material removal rate is very low, and the efficiency requirement of mass production is difficult to meet. (2) For chemical mechanical polishing, the prior art mainly relies on the chemical oxidation of an oxidant, and the oxidation rate is limited by the conditions of the concentration, temperature, pH and the like of the oxidant, so that the lifting space is limited. (3) For auxiliary chemical mechanical polishing, although electrochemical auxiliary, photocatalytic auxiliary and other methods can improve the oxidation efficiency, an additional power supply system or light source equipment is needed, and the process complexity and the cost are increased. (4) The mechanism research is insufficient, namely the prior art is insufficient in microscopic mechanism research such as charge transfer, active species generation and the like on the surface of the material in the polishing process, and the further optimization of the technology is limited. Disclosure of Invention In view of the above-described drawbacks and deficiencies of the prior art, it is an object of the present invention to provide a method for chemical mechanical polishing of a substrate, in particular silicon carbide, based on triboelectric charge enhancement, wherein the triboelectric charge enhances catalytic reactions in solution (e.g. triboelectric charge enhanced organic wastewater degradation, etc., xinliang Liu, et al, APPLIED CATALYSIS B: environmental, 312, 2022, 121422) which have been studied in several documents but are different from polishing. The invention specifically aims to solve the following technical problems: (1) A new physical strategy is provided for realizing the surface oxidation enhancement of a substrate, particularly SiC, namely, utilizing the electronegativity difference between materials, forming electron transfer and generating friction charges through mutual physical friction between abrasive materials and the substrate, such as SiC, thereby increasing the types and the amounts of reactive oxygen species (Reactive Oxygen Species, ROS) and improving the surface reaction rate of the substrate, such as SiC, and further improving the polishing rate of the substrate SiC. (2) On the premise of not increasing the complexity of equipment, the polishing rate of the material is obviously improved