Deep reactive ion etching of PZT ceramics and PMN-PT single crystals for high frequency ultrasound transducers

Micromachining fabrication technique based on thick photoresist lithography and ICP enhanced deep reactive ion etching of PZT ceramics and PMN-PT single crystals has been investigated to fabricate 1-3 composite piezoelectric materials for high frequency ultrasound transducer applications. The experiment procedure includes thick photoresist patterned lithography, Ni hard mask electroplating and ICP enhanced deep reactive ion etching using chlorine gas. PZT ceramic pillars with a height of 43.78 μm and a sidewall angle of 78.9° were obtained. The optimized etching parameters for PZT ceramics were etching rate of 6.25 μm/h, and PZT/Ni etching selection ratio of 6.9. PMN-PT single crystal pillars with a height of 30.74 μm and a sidewall angle of 84.3° were obtained. The optimized etching parameters for PMN-PT were etching rate of 10.25 μm/h and PMN-PT/Ni etching selection ratio of 14. The 1-3 piezoelectric composites fabricated by PZT and PMN-PT pillars are promising materials for fabrication of high frequency ultrasound transducers.