Micro-patterning of 0.70Pb(Mg_1/3Nb_2/3)O₃-0.30PbTiO₃single crystals by ultrasonic wet chemical etching

Ultrasonic-assisted wet chemical etching process was developed for thinning and pattering of single crystalline 0.70Pb(Mg1/3Nb2/3)O3-0.30PbTiO3(0.70PMN-0.30PT) thin layers for micro-electromechanical systems (MEMS) applications. 50 kHz ultrasonic bath with appropriate intensity turned out to be an effective way to speed up the etching process while maintain a constant etching rate. The relationships of etching rates versus chemical concentrations, temperatures and crystalline orientations were investigated. It was found that the chemical etching is thermally activated with an activation energy Eaof 67.7 kcal/mol, and the highest etching rate (6.2 μm/min) was achieved by ultrasonic-assisted etching along the <1-10>cubdirection at room temperature. The feasibility of micro-scale patterning of PMN-PT single crystal layers was also demonstrated by using patterned Au/Cr layer as the etching mask.