Study On CMP Slurry Of Single Crystal Sapphire

Single crystal sapphire, which has wonderful thermal character, wearability, electrical properties, dielectric property, Moth hardness of 9 level, good stability in high temperature, melting point 2030℃, has been widely used in the filed of photoelectron, communication, national defense, scientific research etc. With the development of science and technology, the demand of machining accuracy and surface integrity for sapphire become higher. However, up to now, there are few papers dealing with the ultra-precision technology of single crystal sapphire substrate, especially the ultra-precision machining theory and the pivotal technology by which the final surface quality substrate is achieved.The chemical mechanical polishing (CMP) technic is now publicly considered the best and most effective planarization technic. The CMP slurry has both the chemical erosion effect and the mechanical grinding effect on the surface being processed. But because of the complexity of the CMP technic, the CMP mechanism and the function of the CMP slurry is still unknown and is asking for further research. Besides, there are still some problems such as: metal ions contamination, low dispersal quality and low material removal rate, etc, which restrict the improvement of the CMP technic.In this paper, the subject of CMP slurry prescription for single crystal sapphire is proposed. For reducing metal ions content, improving material removal rate and dispersal, the choice of slurry prescription and optimization is studied through many of theories and experiments. Meanwhile, the material removal mechanism and acquired productions of slurry has also been discussed. At last, the ingredient and prescription of slurry is found, and the slurry has proved to own well properties.Firstly, the CMP technics has been studied in this paper. The factors that influence the CMP quality most have been found. At the same time, the projects of selecting ingredients and optimizing prescription have been established. Secondly, the function of main ingredients has been analyzed. The single factor experiments of every ingredients of slurry have been carried out on the ZYP200 lapping/polishing machine. Meanwhile, the nanometer abrasive, the inorganic alkali, the organic alkali, the dispersant and the surfactant have been selected, which is fit CMP of single crystal sapphire. Basing on these selected ingredients, other experiments has been carried out to improve the prescription and to find the appropriate process parameters. A kind of high quality slurry has been developed through studying on the mechanism of which the quantity of various slurry ingredients and the process parameters affect the polishing effect.The paper provides a kind of systemic researching methods and a group of useful experimental statistics for improving the polishing quality of the slurry, increasing the material removal rate and optimizing the slurry capability. It has significant values for improving the planarization technique of single crystal sapphire.