Processing and Functional Evaluation of Titanium Thin Films for Biomimetic Micro Actuator

Titanium (Ti) thin films were created on glass and Pb(Zr, Ti)O3 (PZT) substrates using magnetic RF sputtering apparatus. Nano-indentation tests were carried out to study the influence of the Ti thin layer on piezoelectric properties. The piezoelectric properties of the PZT plate and a Ti sputtered one were also measured by laser Doppler vibrometer. Furthermore, some characteristics, such as crystalline structure, depth profiles, and surface roughness of the films were observed by means of an atomic force microscope (AFM). Main conclusions obtained in this study are summarized as follows: (1) From detailed observation and analytical results of AFM, the surface roughness, Ra, tends to increase as Ti film thickness increases. (2) Some of the mechanical properties, such as reduced modulus Er and hardness H obtained from nano-indentation tests, are significantly related to film thickness. (3) The validity of piezoelectric finite element analysis (ANASYS program) for deformation of a piezoelectric material was investigated. As a result, piezoelectric response properties are present in as-received PZT specimens and Ti-sputtered PZT specimens. Experimental and FE analytical results indicate that the piezoelectric coefficient is significantly influenced by Ti layer.