Method And Experiment Of Wafer Micro Hole Machining With High Depth-diameter Ratio Based On Picosecond Laser

In the three-dimensional chip processing process,the preparation of wafer micro-holes such as through silicon via(TSV)is an important part of them,and the micro-holes quality is an important factor in ensuring the packaging process and interconnection characteristics.At present,the main micro-hole processing methods are deep reactive ion etching and laser etching,in which laser etching removes material through high-density laser irradiation to form micro-holes,but laser micro-hole etching has the problems of large pore size,difficulty in optimizing laser parameters,and low serial processing efficiency.Therefore,how to laser process smaller diameter micro-holes and improve processing efficiency are the key issue in wafer micro-hole processing.This article focuses on the issue of parallel high-quality micro-hole processing base on the ultraviolet picosecond lasers,during the study of the laser micro-hole processing technology,optimization of laser parameters,and parallel processing of the laser beam splitting,a laser suspension process is proposed,which can improve the micro-pore removal capacity and reduce the micro-hole tape.The method of laser processing parameters optimization based on response surface model is proposed,the laser parallel processing method based on laser beam splitter is explored.Through the wafer micro-hole machining experiments,the influence of parameters for improving the micro-hole processing quality is obtained,providing technical support for high-depth-ratio wafer micro-hole machining.The main research contents are as follows:1.The principle of interaction between the laser and the material is studied and analyzed,Based on the experiments on the effect of micro-pore removal on the quality of micro-pore,a suspended processing method is proposed to improve the chip removal ability of the micro-holes,and reduce the micro-hole taper.The experimental of wafer suspended processing method and the unsuspended method were processed to verify the effectiveness of the suspended processing method in reducing the micro taper and improving the micro-hole quality.2.The multi-parameter optimization problem of laser micro-hole machiningprocess was studied,a multi-parameter optimization method based on response surface model was proposed.The response surface model method is established for the laser pulse energy,pulse frequency and processing time,and the diameter of the micro-hole outlet.The secondary response surface model is solved by Matlab base on the experimental data.Experiments show that the response surface can effectively optimize the laser parameters and give the influence law between each parameter and the diameter of the micro-holes.3.The laser beam splitting method is studied,and the laser beam splitting optical path is designed.The Daman grating is selected as the laser beam splitter and its main parameters to meet the requirements of the spectroscopic energy with uniform splitting energy,focusing on the same plane,and adjustable optical splitting distance.The laser parallel processing can be achieved by setting up,and debugging the laser beam splitters.Experiments show that this method can realize the parallel processing of the laser beam splitting,with uniform splitting energy,and good consistency of micro-holes,and can effectively improve the processing efficiency.