Method And Experimental Study On Laser Assisted Anodic Bonding

Anodic bonding is one of the most important key technologies of MEMS bonding encapsulation method,which has been widely used in the packaging of micro flow pump,micromachined gyroscope,micro pressure sensor and micro accelerometer device.Genera-lly,the heating method of the anode bonding device is to use the heating plate to heat the whole body,which is not suitable for the packaging of the chip with a soften plastic component or a temperature sensitive precision structural component.With the rapid development of science and technology,MEMS is becoming more and more prominent in the direction of miniaturization,complicated structure and diversified functions.In the premise of ensuring the bonding strength of the samples,how to effectively control the thermal effect on the whole of bonding samples in the anodic bonding process and how to realize the local selective bonding has become an urgent problem to be solved.Therefore,in order to meet the special requirements of the packaging of MEMS,based on the mature technology and the high reliability of the anodic bonding,it is necessary to develop a new MEMS packaging technology-Laser Assisted Anodic Bonding,which has very important practical significance.Firstly,through the analysis of the process of anodic bonding and anodic bonding to obtain three important conditions for successful experimental parameters,then based on the principle of the thermal effect of the laser and the material,the mechanism of intrinsic particle migration in laser diode bonding was summarized and the feasibility of the laser anode bonding system was analyzed.According to the transmission of experimental materials to determine the performance parameters of important equipment,and carries on the optimization design of key parts,finally established the laser anodic bonding optical system including laser loading system,voltage applying system and bonding platform system.Next,According to some fixed parameters in the experiment and the practical effect of laser high speed walking in the experiment,the finite element method(ANSYS R16.2)is used to establish the numerical model of the silicon wafer.And through the simulation of different laser power formed on the silicon wafer surface temperature distribution to obtain the bonded surface melting temperature of the laser power threshold.In the end,in order to determine the power range of laser anode bonding,the experimental study of anodic bonding and laser fusion bonding was carried out according to the simulation data.The laser power is taken as the experimental factor and the bonding strength is taken as the experimental index to investigate the optimum process parameters of laser diode bonding in the bonding of silicon and BF33 glass.Scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS)were used to analyze the microstructure of the bonded samples and the determination of the composition of the different regions.The internal mechanism of the new bonding technique of laser anode bonding was preliminarily verified.Based on the study of the local bonding experiment of laser anode bonding,the advantage of selective bonding has been proved in this bonding technique and it can be applied to the bonding of similar MEMS engineering materials.