Novel fabrication technique for NiTi and TiN micro-structures by femtosecond lasers

M A Jithin,S Mohan,N K Udayashankar,K L Ganapathi

doi:10.1088/1757-899x/872/1/012113

Abstract

NiTi shape memory alloy (SMA) thin films were deposited onto silicon substrate using pulsed DC magnetron sputtering technique. To obtain crystalline NiTi thin films has to be synthesized at higher temperatures (475 - 525) °C. This high temperature requirement restricts the ease in conventional lithographic procedures. The recent advancements in the laser micromachining lend their applications into the fabrication of miniaturized systems. The femtosecond lasers (FSL) allow non-thermal processing of materials by ablation. This work focuses on the deposition and fabrication of NiTi (≈1.5 μm. thick) and titanium nitride (TiN ≈0.3 μm. thick) thin films based miniaturized systems by femtosecond laser bulk micromachining. The NiTi and TiN microstructures were release by bottom silicon etch using reactive ion etching chlorine chemistry (RIE-Cl).

Highlights

Among the various micro-actuator domains like; piezoelectric, electrostatic, magnetic and bimorph systems; the NiTi based shape memory alloy materials have got a considerable attention because of their excellent work output and biocompatible nature [1, 2]
This work focuses on the deposition and fabrication of NiTi (≈1.5 μm. thick) and titanium nitride (TiN ≈0.3 μm. thick) thin films based miniaturized systems by femtosecond laser bulk micromachining
The low temperature, low stable phase is FCC known as martensite (B19) and the high temperature, high stable phase is BCC known as austenite (B2) [3, 4]

Summary

INTRODUCTION

Among the various micro-actuator domains like; piezoelectric, electrostatic, magnetic and bimorph systems; the NiTi based shape memory alloy materials have got a considerable attention because of their excellent work output and biocompatible nature [1, 2]. The high power to weight ratio, large achievable strain, low driving voltage and excellent mechanical properties makes NiTi SMAs a promising candidate in micro-actuator domain [7, 8]. Because of it excellent biocompatibility, NiTi based SMAs are used in biomedical devices and surgical tools [9, 10]. The TiN thin films are being used as heating element in MEMS devices for heating the localized areas [21]

EXPERIMENTAL

RESULTS

CONCLUSION