Patterned Ti-based shape memory alloy films have attracted considerable research effort in recent times owing to their favorable characteristics for potential applications as micro-actuators in microelectromechanical systems. Titanium-Nickel-Palladium (TiNiPd) shape memory alloy film can be used to fabricate micro actuators for high temperature applications. These films are to be patterned to realize the microactuators. We have made an attempt to laser pattern amorphous TiNiPd shape memory alloy films on a silicon substrate, deposited by DC-magnetron sputtering using a Ti₅₄Ni_36.8Pd_9.2 alloy target. These films were micromachined by KrF excimer laser induced ablation at 248nm. Two different mask patterns have been used, one having an array of squares and circular features and the other having lines of varying widths and pitch. Three types of film removal mechanisms were observed i) due to amorphous to crystalline phase transformation, ii) due to solid to liquid transition followed by crystallization and iii) removal of the film along with silicon substrate melting. These mechanisms of TiNiPd film removal from silicon substrate appear to be similar to the mechanisms of TiNi film removal from silicon substrate reported in the literature. This paper presents the dependence of TiNiPd material removal mechanisms and feature quality on laser parameters such as fluence, pulse repetition frequency and number of shots.

Date Published: 2 April 2004
PDF: 11 pages
Proc. SPIE 5276, Device and Process Technologies for MEMS, Microelectronics, and Photonics III, (2 April 2004); doi: 10.1117/12.522911

Published in SPIE Proceedings Vol. 5276:
Device and Process Technologies for MEMS, Microelectronics, and Photonics III
Jung-Chih Chiao; Alex J. Hariz; David N. Jamieson; Giacinta Parish; Vijay K. Varadan, Editor(s)