Stresses in thin film metallization

Stresses in conductors used in microelectronic interconnections are a critical processing and reliability issue. This work examines: 1) the temperature-dependent stress behavior of sputtered and electroplated silver and gold films on silicon substrates; 2) the use of wafer curvature using multiple substrates for the simultaneous determination of coefficient of thermal expansion (CTE) and modulus for thin films. The stress-temperature behavior of gold films on gallium arsenide and aluminum substrates was measured to determine its CTE and modulus. It is shown that electroplated noble metal films have lower stresses than sputtered films, due to larger grain sizes.