Effect of residual stress in Pb (Zr0.52Ti0.48) O3 – BiFeO3 multilayer cantilever structure

Abstract

This paper discussed about the integration issues of Pb (Zr0.52Ti0.48) O3 – BiFeO3 (PZT - BFO) multilayer thin film deposited on silicon substrate for possible application in future micro-electro-mechanical system (MEMS) devices. The PZT - BFO multilayer thin film is deposited on silicon wafer by sol-gel technique. The multilayer film is annealed at 650 °C in air for 60 min. The deposited multilayer film is found to be polycrystalline in nature. The PZT-BFO multilayer exhibited room temperature multiferroic properties (remnant polarization of 37 mC/ cm 2 and remnant magnetization of 3.1 emu / cm 3 ). To fabricate the PZT - BFO multiferroic cantilever structures, a two-mask process flow is developed. Etch rates of the PZT - BFO multilayer (180 nm/ min), ZrO2 buffer layer (35 nm/ min) and SiO2 layer (350 nm/ min) are optimized in CHF3 plasma. The multiferroic cantilever structures are released by isotropic etching of silicon using SF6 plasma. Bending and cracks are observed in the released cantilever structures due to the generation of residual stress in the multilayer thin film. Effect of residual stress on the PZT - BFO cantilever structure is also verified by simulation.