Investigation of Top/Bottom Electrode and Diffusion Barrier Layer for PZT Thick Film MEMS Sensors

Abstract

Top and bottom electrodes for screen printed piezoelectric lead zirconate titanate, Pb(Zr _x Ti_{1 − x} )O₃ (PZT) thick film are investigated with respect to future MEMS devices. Down to 100 nm thick E-beam evaporated Al and Pt films are patterned as top electrodes on the PZT using a lift-off process with a line width down to 3 μ m. A 700 nm thick ZrO₂ layer as insolating diffusion barrier layer is found to be insufficient as barrier layer for PZT on a silicon substrate sintered at 850°C. EDX shows diffusion of Si into the PZT layer.

Keywords:

• PZT thick film
• top electrode
• bottom electrode
• MEMS
• accelerometer
• pMUT″

Acknowledgment

This work is a result of the PiMEMS project which is a collaboration between MIC, InSensor A/S and Ferroperm Piezoceramics A/S and is supported by “The Danish National Advanced Technology Foundation.”