MEMS device having a movable electrode
A microelectromechanical system (MEMS) device includes a semiconductor substrate, a MEMS including a fixed electrode and a movable electrode formed on the semiconductor substrate through an insulating layer, and a well formed in the semiconductor substrate below the fixed electrode. The well is one of an n-type well and a p-type well. The p-type well applies a positive voltage to the fixed electrode while the n-type well applies a negative voltage to the fixed electrode.
1. A microelectromechanical system (MEMS) device, comprising:
a semiconductor substrate;
a MEMS including a fixed electrode and a movable electrode formed on an insulating layer that is formed on the semiconductor substrate;
a well formed on the semiconductor substrate below the fixed electrode, the well having a same polarity as a polarity of the semiconductor substrate; and
an isolation well having an opposite polarity to the polarity of the well and surrounding the well in the semiconductor substrate, wherein the well and the isolation well are in a reverse bias state, while the isolation well and the semiconductor substrate are in a reverse bias state.
2. The MEMS device according to claim 1 , satisfying Vp>0, and 0<Vp−Vwell<Vth, where Vp is a bias voltage of the MEMS, Vwell is a voltage applied to the well below the MEMS, Vth is a threshold voltage at which an inversion layer is formed in the well, wherein the semiconductor substrate is a p-type substrate and the well is a p-type well, while the isolation well is an n-type well.
3. The MEMS device according to claim 1 , satisfying Vp<0, and 0<Vp−Vwell<Vth, where Vp is a bias voltage of the MEMS, Vwell is a voltage applied to the well below the MEMS, Vth is a threshold voltage at which an inversion layer is formed in the well, wherein the semiconductor substrate is an n-type substrate and the well is an n-type well, while the isolation well is a p-type well.