Optimization of poly (methyl methacrylate) as sacrificial layer for application in low temperature MEMS

The recent development in smart systems can benefit from the integration of MEMS and CMOS technology with emphasis on low temperature processing that utilizes low cost substrates. The main constraints in MEMS/IC process are high thermal budget and harsh chemical usage in the processing. Polymers are generally used in surface micromachining as sacrificial layers, but face a problem of high temperature (150–250°C) baking cycles and the cost associated with it. This paper reports an in-house preparation (optimized formulation) and optimization of PMMA solution with a view to solve the problem with high temperature processing. Surface micromachined silicon nitride cantilevers using PMMA as sacrificial layer is fabricated to prove its feasibility for low temperature MEMS applications.