Study On Laser Assisted Waterjet Processing Technology Of Micro Groove On Gallium Arsenide Wafer

Gallium arsenide(GaAs)is widely used compound semiconductor.Due to its characteristics of high brittleness,its dicing processing technology has always been a difficult problem in wafer manufacturing.Laser assisted waterjet technology is suitable for micromachining of hard and brittle materials.An inclined high-pressure waterjet can remove the materials softened by laser heating,and plays the role of cooling and reducing thermal damage.Cutting performance of GaAs wafer microgrooves processed by laser assisted waterjet was studied experimentally.Regression prediction models for microgroove depth,microgroove width and material removal rate during laser assisted waterjet processing were developed using response surface method;A temperature field simulation model and a material removal simulation model of GaAs wafers processed by laser assisted waterjet were established.The processing quality of microgrooves on GaAs wafers machined by laser assisted waterjet was experimentally studied and evaluated,and active control strategies were proposed for wafer dicing technology requirement.The cutting performance of laser assisted waterjet processing technology of GaAs wafer microgrooves was studied experimentally.The research results show that processing factors(average laser power,waterjet pressure,processing speed,waterjet inclination angle,focal plane position,and processing times)have significant influence on microgroove depth,microgroove width and material removal rate.The microgroove depth,microgroove width and material removal rate increase with increasing laser pulse energy,decrease with increasing waterjet pressure,and the material removal rate increases significantly with increasing processing speed.Prediction models of microgroove depth,microgroove width and material removal rate obtained by laser assisted waterjet were established.The effects of process parameters interactions on microgroove characteristics were investigated,and the results reveal that the interaction between average laser power and waterjet pressure have greatest impact on microgroove depth,width and material removal rate.Optimized process parameters were obtained using the models under different optimization constraints.Variation rules of the maximum shear stress and convective heat transfer coefficient in the wall jet zone were revealed.A simulation model of the temperature field of GaAs wafers processed by laser assisted waterjet was established,and the results show that the maximum temperature of the material under the action of a single pulse reaches 3300K.The temperature of the laser center point on the upper surface of the workpiece changs in a sawtooth shape with the action of the pulse,and the temperature at the end of the action of a single pulse is positively correlated with average laser power.A simulation model of material removal was established using birth-death element method.Simulated removal profiles were obtained under different laser average power and processing speed conditions.Comparative experiments of dry laser,low pressure waterjet assisted laser and laser assisted waterjet technologies for microgrooves processing on GaAs wafers were conducted.The results show that laser assisted waterjet technology is suitable for processing GaAs materials.It can process large depth and high quality microgrooves with no contamination on the wafer surface,minimal heat affected zone,maximum depth to width ratio and uniform microscopic morphology on the processed surface.Laser assisted waterjet processing of GaAs microgrooves has thermal decomposition,oxidation reaction and thermal cracking behavior on the processed surface,with no obvious thermal damage on the subsurface.Active control strategies for improving laser assisted waterjet technology processing quality were proposed for the technical requirements of dicing processing.