The Ice Tray Of Chemical Mechanical Polishing Of Single Crystal Gallium Arsenide Film Mechanism And Process Research

Single crystal gallium arsenide is a new semiconductor material has developed after germanium and silicon. It is one of the most important and most mature compound semiconductor materials, mainly used in the field of optoelectronics and microelectronics.Gallium arsenide is typical hard and brittle that has low plasticity. Use the ordinary processing technology and parameters only lead to brittle crack removal without obvious shear flow phenomena like the metal. When the cutting force is too high, the material will undergo brittle fracture, which will affect the quality and integrity of the surface.For characteristics of ultra-precision machining of single crystal gallium arsenide chip, the CMP process of single crystal gallium arsenide chip with nano-silica abrasive system freeze pad was studied, the content of cutting process, pre-processing, preparation of frozen nano-silica abrasive ice pad and polishing were discussed. The pre-processing of single crystal GaAs films includes grinding and abrasive chemical mechanical polishing. When the major work completed, the achievement include these:1. In the cutting process of single crystal GaAs film, cutting speed and feed rate of midline would influence the surface quality. When the feed rate is small, the increased of cutting speed can significantly improve the surface roughness of GaAs chips; when the feed rate is larger, line speed on the surface have little effect on the roughness of GaAs films.2. In the process of free abrasive chemical mechanical polishing, When the PH value is 9~11.5, the pressure is 0.08MPa, the surface roughness would be 8.0nm, the pressure is 0.1MPa, the surface roughness would be 7.81nm. If the pressure increased to 0.2MPa, the surface roughness would be 9.15nm.3. The mechanism of brittle-ductile transition influenced by temperature on the single crystal gallium arsenide chip by indentation experiments using vickers hardness tester were analyzed. When the load is lower than 0.244N, the hardness of GaAs chips is increasing with the load become high, and no cracks. When the load is higher than 0.244N, the hardness of GaAs film is decreasing with the load become high, and accompanied by cracks and expansion.4. The formula of slurry formulations is mixture liquid of nano-silica slurry liquid and deionized water by proportion of 3:1. H2O2 will be used to adjust PH value between 9.5 ~ 10.5. The quality of ice pad will be good when 10% nano-silica in the slurry.5. Use the method of open mold and frozen layer could significantly reduce the internal stress, cracks, bubbles and impurities in nano-silica abrasive ice pad; at the same time, the quality of surface can be increased by using transparent quartz glass polishing jig and UV adhesive.6. With an ambient temperature of 10±0.5℃, spindle speed 100rpm, eccentric distance of 50mm, polishing pressure of 0.1MPa, the average value of surface roughness could be 5.71nm, and the value of center is less than the value of edge(average value of three points on edge is 6.39nm, average value of three points on center is 5.01nm in this experiment.