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What’s Chemical Mechanical Polishing ?

Time: 2022-11-02 Hits: 156 views

Chemical mechanical polishing is the process of removing and flattening the surface material of the workpiece through the synergy of chemical corrosion and mechanical wear. The wafer undergoes chemical oxidation under the action of the polishing liquid, and a chemical reaction layer is formed on the surface, and then the reaction softening layer is removed under the mechanical action of abrasive grains.

Because chemical mechanical polishing technology involves multidisciplinary knowledge, such as chemistry, physics, friction, mechanics and materials science, etc., there are many factors affecting its polishing effect, mainly polishing fluid (abrasive particles, oxidants, pH value, additives, etc.), polishing Pad (hardness, elasticity, surface topography, etc.) and polishing parameters (polishing pressure, head/disk speed, slurry flow, etc.).

Among them, the polishing liquid is the core of chemical mechanical polishing technology, so its influence is decisive. Generally speaking, CMP polishing liquid is composed of abrasive grains, oxidants, deionized water and additives, so the polishing effect can be regulated from these factors – for example, the simple abrasive grains include the types of abrasives, abrasive grains diameter, abrasive particle concentration, etc.

At present, the oxidants commonly used in CMP polishing liquids are mainly H2O2 and KMnO4, and the abrasive particles are mainly SiO2, CeO2 and Al2O3. Feng et al. used 30-135nm modified silicon solution to fine-polish SiC wafers, and found that the residual damage layer after the rough polishing process could be completely removed, thereby obtaining a high-quality polished surface.