Patent ID: 9174837
Filing Date: 2015-11-03
Classification: B81B,G01R

Abstract:
1. A method for measuring a retained surface charge within a MEMS device comprising: (i) performing an initial voltage signal sweep on the MEMS device, the MEMS device including a first and second electrode; the initial voltage signal sweep including applying a first force voltage signal to a substrate and the second electrode of the MEMS device and gradually changing the applied first force voltage signal, which changes a capacitance between the first and second electrode; (ii) applying a stress voltage signal to the MEMS device for a pre-determined amount of time, the stress voltage signal causing at least one of the first and second electrodes to retain a surface charge; (iii) performing an at least one additional voltage signal sweep on the MEMS device after applying the stress voltage signal, the at least one additional voltage signal sweep including applying a second force voltage signal to the MEMS device and gradually changing the applied second force voltage signal, changing the second force voltage signal which changes the capacitance between the first and second electrode; (iv) calculating a signal shift based upon data obtained in (i) and (iii), the signal shift being representative of the retained surface charge.