In this paper, the effects of annealing temperature after pre-bonding device wafer and cover wafer during wafer fusion bonding process on the electrical properties of MEMS-based capacitive microphone with 0.53 μm thick poly-Si membrane were investigated. By the annealing in N2 ambient (14 SLM) at 900°C for 30 min, the device exhibited capacitance of 2.0 pF with pull-in voltage of 12 V. The significantly improvement of electrical properties is related to the reducing of residual stress in poly-Si membrane to near-zero level by using suitable annealing condition.
