Young's modulus, fracture strain, and tensile strength of sputtered titanium thin films

The internal stress of sputtered titanium thin films was optimized for Micro Electro Mechanical System (MEMS) applications and the strength properties of the films were investigated. Low internal stress was obtained for 0.5-μm thick films by controlling the argon gas flow rate and for 1.0-μm thick films using the multiple deposition process. The Young's modulus, tensile strength, and maximum elongation of the titanium films were measured using a thin film tensile tester with an electrostatic force grip system. The tested films were 0.5 or 1.0 μm thick, 20 or 50 μm wide, and 100 or 500 μm in gauge length. The averages of the Young's modulus and the tensile strength were 90 and 0.65–0.8 GPa, respectively. A large maximum strain was observed, showing slip along the maximum shear stress directions, which will enable more reliable MEMS devices.