Effect of Ar Gas Pressure on Mechanical Properties of Sputtered Ti Thin Films

Abstract

The effect of sputtering gas (Ar gas) pressure on the mechanical properties of free-standing Ti thin film membranes of 300-400 nm thickness, microfabricated by magnetron sputtering, has been studied by using a novel tensile testing machine. These free-standing thin film membranes are extremely difficult to handle because they are fragile. Therefore, the thin film test specimens were fabricated in Si frames to protect them. Sputtering gas pressure was varied from 1.5 to 15 mT. The stress and strain of the thin films was measured continuously from elastic deformation to fracture. Both the tensile strength and the strain at fracture of the thin films were affected by the sputtering gas pressure. The tensile strength of thin films increased with decreasing gas pressure. However, there was no obvious trend between the sputtering gas pressure and Young's modulus of the thin films. The experimental results confirmed that the Ti thin film membranes are more reliable with decreasing the gas pressure.