A Study of the Mechanical Properties of Indium Phosphide (InP) Based Mems Structures

Abstract

Indium Phosphide (InP) based optical MEMS devices find numerous applications in high speed networks, which include devices such as variable attenuator, wave guides, vertical cavity surface emitting lasers (VCSEL), optical switches and filters. This work covers optimisation aspects in fabrication and identifying the major mechanical properties of InP based MEMS devices such as membranes and cantilevers. Based on the results of the characterizing methods, a potential optical MEMS device with minimum profile deviations and stress values was identified.Mechanical characterization tests such as nano-indentation and micro-Raman spectroscopy were carried on InP based micro-cantilevers and membranes. Nano-indentation tests on microcantilever beams revealed the structural and bending properties along with Elastic modulus and hardness. Optical interferometry technique based 2D and 3D profile measurements and micro-Raman studies were carried out to study the out of plane curvature and the residual stresses of the membranes. This study analysed the effect of membrane dimensions on formation of stresses which leads to undesirable out of plane strain and thus helped to identify a structurally superior MEMS device.