Research On CMP Mechanism And Process For Monocrystalline Germanium Wafers With Ice-fixed Abrasive Polishing Pad

Precision and ultra precision machining technology is the advanced manufacturing technology which is adapted to the modern high technology. It is a new achievement with the development of mechanical technology, modern electronics, sensing technology, optical and computer. It is the basic technology in the field of technology which plays a vital role in the national defense science and technology modernization and national economic construction. At present, the mainly ultra precision machining method in hard and brittle crystal is chemcial mechanical polishing, chemical mechanical polishing is a kind of advanced manufacturing technology, which combines mechanical technology, chemical technology, sensing technology and computer technology.In this paper, a new method of Ice-fixed Abrasives to realize high quality machining of monocrystalline germanium wafer was proposed, which provides a new idea for the precision and ultra precision machining of hard and brittle materials and improves the international competitiveness of precision machining technology. Based on the analysis of the effect on the sub surface damage of monocrystalline germanium wafers with three lapping ways such as thermosetting fixed abrasive, ice-fixed abrasive and free abrasive lapping, the dispersion process of submicron SiC powder and the new type of abrasive polishing pad were prepared and the process of ice-fixed abrasive polishing monocrystalline germanium wafer was explored. The main work and achievements are as follows:1. Three ways such as thermosetting fixed abrasive, ice-fixed abrasive and free abrasive lapping were used to lap monocrystalline germanium wafers. Nano indentation method and HF acid corrosion rate were used to measure the thickness of subsurface damage of monocrystalline germanium wafers. In addition, cross section surface profile and data comparison were used to analyse the morphology of subsurface damage layer. Based on these, optimal processing method was found.2. The dispersion process of submicron SiC powder was studied. Single factor and orthogonal experiments was used to study the effect of milling time, ultrasonic time, dispersion agent type, dispersant concentration and pH value on the dispersion process of submicron SiC powder. Suspension with good dispersion effect was configured, which lay a foundation for the further preparation of the polishing pad.3. The process of ice-fixed abrasive polishing monocrystalline germanium wafer was explored. Different polishing parameters such as temperature, concentration of abrasive, abrasive type, pressure, speed, and time on the polishing performance of ice-fixed abrasive polishing pad were analyzed. Roughness and removal rate were used to express the results.