Design of a Sensitive MEMS Capacitance Diaphragm Gauge Based on Au-Si Eutectic Bonding

In order to solve the vacuum leakage caused by the electrode lead in the vacuum cavity,and further expand the lower limit of vacuum gauge measurement,a design scheme of MEMS capacitor diaphragm gauge (CDG) based on Au-Si eutectic bonding was proposed.In this paper,a complete manufacturing process of MEMS CDG is put forward.It is proposed to select concentrated boron doping technology to develop pressure-sensing diaphragm,and to realize the sealing of vacuum cavity by anodic bonding and Au-Si eutectic bonding.Finally,based on the theoretical calculation and the finite element model,the overall size of the pressure-sensing diaphragm was optimized for different width-thickness ratio.Under the optimal size parameters,compared with the structure of the fixed electrode in the measurement cavity,the sensitivity of the designed new non-contact MEMS CDG is improved by 9.5 times,up to 38 fF/Pa.The measuring range of the MEMS CDG is within 1~1 000 Pa.