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

The effect of sputtering gas (Ar gas) pressure on the mechanical properties of free-standing Ti thin film membranes of 300-400 nm thickness, micro fabricated by magnetron sputtering, has been studied by using a novel tensile testing machine. These free-standing thin film membranes are extrem ely difficult to handle becaus e 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 fractu re of the thin films were affected by the sputtering gas pressure. The tensil e strength of thin films increased with decreasing gas pressure. However, there was no obvious trend between the sputtering gas pres sure 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.