On-wafer-packaging of crystal quartz based devises using low-temperature anodic bonding

Low-temperature bonding of crystalline quartz and silicon wafers is described. The bonding has a big potential for MEMS applications because it could integrate the processing and packaging in a single high-tech process. In this work, strong bonding of silicon and crystal quartz wafers close to the mechanical strength of the initial materials has been achieved. Tensile test shows a disruptive stress of the samples at about 35 MPa. High bonding strength is associated with minimization of the residual stresses, optimization of surface activation, and application of an electric field during annealing. Lowest possible annealing temperature and the optimum thickness ratio of silicon and quartz layers have been used in order to minimize the residual stresses.