Mechanical design and fabrication of multi-layer indium phosphide freestanding microstructures for a MOEMS microspectrometer

The aim of this paper is to report on the optimization of major technological steps in the fabrication of a micro-opto-electro-mechanical system (MOEMS) composed of an actuable stack of free-standing indium phosphide layers. The projected MOEMS device is a microspectrometer based on a tunable Fabry–Pérot resonator embedding a near infrared photodiode. Two specific structure shapes have been designed and optimized using finite element modelling in order to reduce the sensitivity to residual strain and to improve the compactness of the devices. Various test devices have been fabricated ranging from single isolated structures to one-dimensional (1 × 9) or two-dimensional (3 × 3) arrays. Experimental measurements using white light interference profilometry show a good agreement with design simulations.