Research On Fabrication Process Of TGV Substrate Aimed At Wafer Level Vacuum Packaging

As many(Micro-Electro-Mechanical System,MEMS)devices need a vacuum environment to achieve high performance,they need to be vacuum packaged.Comparing with device level vacuum packaging,wafer level vacuum packaging has lots of advantages for that they are more efficient,with smaller size and lower cost.As a new method of wafer level vacuum packaging,TGV(Through-Glass Via)technique is a new interconnected technology,providing 3-dimensional packaging with good sealing effect.This paper focus on the fabrication of the TGV substrate and the content includes:1.The background of this research is introduced,and the methods of wafer level vacuum packaging are fully investigated.Then,the significance of this research are discussed and clarified based on the results of previous study.2.The fundamental principle of TGV technique based on glass reflow is analyzed,and the theoretical model of Pyrex 7740 glass reflow under high temperature is established.Then,the influence of different factors on the reflow is deduced.Finally,corresponding solutions are put forward after analysing the cause of thermal stress on TGV substrate.3.The process parameters of the glass reflow are optimized.The experimental results show that a good bonding effect can be achieved when the voltage and temperature of anodic bonding are set to be 800 V and 400℃.The optimum parameters are also obtained,which are 1100℃ of reflow temperature and 4h of reflow time.4.The design of substrate and process of TGV based on glass reflow is accomplished.The parameters during the fabrication are optimized,including substrate thickness,shape of feedthrough,barrier thickness,etc.Meanwhile,optimization and improvement on the strength of the side of TGV deep feedthrough are achived based on the previous schemes and self-demands.5.The TGV substrate based on glass reflow is fabricated.Then,the strength and reliability test are conducted,and the microstructure is observed using microscope.Test results show that the fabricated TGV substrate has the required strength and reliability,and the insulation between the feedthroughs is achieved,which prove the eligibility of the fabrication.