Fabrication of a silicon based vertical sensitive low-g inertial micro-switch for linear acceleration sensing

Most of the MEMS inertial switches developed in recent years are intended for shock and impact sensing with a threshold value above 40 g. These switches were designed as lateral sensitive and were fabricated using either electroplating or silicon micromachining technology. Considering on the other hand the low-g micro-switch (threshold value <10 g), usually consists of a high volume proof mass and a low stiffness spring, were rarely reported because these switches were less practical to be fabricated with lateral sensitive structure design. In this paper, we report on a silicon based vertical sensitive low-g inertial switch designed for linear acceleration sensing. The inertial switch consists of a cylinder shaped proof mass, suspended by circular shaped spiral spring. The fabrication process is based on a customized symmetrical double-buried layer SOI wafer with standard silicon micromachining. The centrifugal experiment results show that the threshold value is around 5.5 g which is close to the designed value.