Thermal transient characterisation of the etching quality of micro electro mechanical systems

The paper presents a non-destructive thermal transient measurement methodology that can reveal micron-sized differences among etched layers of MEMS structures. MEMS resonator devices and bridge structures made of polycrystalline silicon differing in etching times were investigated by simulations and measurements as well. Simulations showed that tiny differences in etching times of the sacrificial layers can cause significant changes in heat distribution. In the measurement process the voltage transients of the devices were captured. The results were transformed into temperature transients. Utilising temperature transients, small differences could be detected among the structures. The paper demonstrated simulation and measurement experiments by the applicability of thermal transient methodology for non-destructive testing of the etching quality in MEMS structures.