Simultaneous Analysis of Local Device Layer Thickness and Film Stress on Cantilevered MEMS Structures

Abstract

This paper reports on a passive MEMS structure facilitating the local measurement of both, the device layer thickness and residual film stress with white light interferometry (WLI). The structure consists of a released single-side clamped plate (SSCP) and a step-profile etched through the device layer down to a silicon dioxide layer. In doing so, both the static deflection and the thickness are determined, independent of material parameters, such as the index of refraction or surface roughness. Both key properties can be efficiently measured with the same tailored WLI set-up.