Research Of Chemical Mechanical Fixed-abrasive Polishing Pad Of SiC Single Crystal

Semiconductor lighting has been one of the advanced technology and fast developing field in 21 century. The core of semiconductor lighting device is a light emitting diode(LED), which is the heart of the semiconductor chip. The underlay materials for Ga N based on LED are more, but can be used for the commercialization of substrate material, only the sapphire(Al2O3) and silicon carbide(Si C) substrate. The Si C single crystal has became a international hotspot of research on semiconductor lighting,microelectronics, photoelectron and new materials, because of being an ideal materal for building high temperature,high frequency,high power,anti radiation, short wavelength light-emitting and optoelectronic integrated devices,which has many good properties, such as good chemical stability, good electrical conductivity, good thermal conductivity, does not absorb visible light, unique large band gap, high breakdown electric field and high electron mobility, keeping the market share is second only to Al2O3 on the main commercial substrate material of gallium nitride(Ga N) extension.The technique in preparation of LED requires the Si C substrate to reach ultra-smooth without damage, the chemical mechanical polishing(CMP) is the most practical and effective technique to reach global planarization which has been widely used in device fabrication such as ULSI. Since the conventional chemical mechanical polishing technology has so many disadvantages such as consumables high cost that has been improved all the time,the fixed abrasive chemical mechanical polishing(FA- CMP) is developed in traditional technique based on a novel CMP planarization technology, which has many advantages.After reviewing the relevant documents, there are no literature reports on fixed abrasive chemical mechanical polishing of Si C single crystal,therefore, the project was proposed about it, which provided the basis for the theory and technology of fixed abrasive chemical mechanical polishing of Si C single crystal.The main work and results are as follows:1 According to the physical and chemical properties of free abrasive chemical mechanical polishing pad, the substrate surface structure of polishing pad was discussed, such as hardness, abrasive embedded firm and convenience. The components of fixed abrasive chemical mechanical polishing pad of Si C single crystal were studied through a lot of experiments and analysis. The components as follows:polyurethane acrylate(oily),polyethylene glycol two acrylate,diethylene glycol two acrylate,2- hydroxy-2-methyl-1- phenyl-1- acetone and additives,and so on. The effect of manufacturing process and polishing were obvious.2 According to the components, the preparation process of UV light curing and the technology of fixed abrasive polishing were researched, and the parameters of UV light curing were obtained through the experiment. The results show that, the effect of curing light was the best when the illumination distance was 25mm; the illumination time was 90 s.3 The idea of hierarchical uv-curable fixed abrasive polishing pad was designed and relevant molds were manufactured. The effect of different layer thicknesses and surface texture structure on material removal rate and surface roughness was studied through a series of fixed abrasive polishing pad made by UV lighting curing, and the structure of the fixed abrasive polishing pad was optimized.4 The fixed abrasive polishing pad and the relevant slurry prepared were being used to determine the Si C single crystal.Compared with the results of free abrasive chemical mechanical polishing, under same conditions the results show that, On the material removal rate side, the fixed abrasive chemical mechanical polishing was far higher, the numerical value of surface roughness was the opposite.