Abstract
The effect of sputtering temperature, sputtering bias, and annealing temperature upon the sheet resistance, WO 3 formation at the Al-Si-Cu/Ti-W interface, and diffraction intensity of the Al 2 Cu precipitates of magnetron-sputtered Al-Si-Cu films were investigated. Statistical methods and microcharacterization techniques were applied to study these effects. Statistical analysis verifies the effect of annealing temperature on the measured sheet resistance. Annealing temperature alone is the dominant factor upon the WO 3 formation at the Al-Si-Cu/Ti-W interface and the Al 2 Cu (211) plane diffraction intensity. Annealed samples are of higher sheet resistance. Increase in sheet resistance is ascribed to the formation of interfacial WO 3 . Reduced electromigration is related to the formation of Al 2 Cu precipitates. Secondary ion mass spectrometry (SIMS) analysis of the as-deposited sample depicts the presence of an excess amount of oxygen atoms at the surface and the Al-Si-Cu/Ti-W and Ti-W/Ti interfaces. Rutherford backscattering spectrometry and SIMS analyses reveal the outdiffusion of W from the Ti-W layer toward the Al-Si-Cu layer, the presence of Si nodules at the Al-Si-Cu/Ti-W interface, and the formation of Ti silicides at the Ti/Si interface. These phenomena are confirmed by transmission electron microscopy, energy dispersive x-ray analysis, and scanning electron microscopy analyses. It is concluded that interfacial oxygen, which reacts with W to form WO 3 upon annealing, warrants further reduction to yield films of better sheet resistance.