Laser evaporation of metal sandwich layers for improved IC metallization

With the further shrink of IC dimensions, metallization becomes the most crucial layer because conductivity and contact resistivity determine the RC constants and thus the speed of the circuits. With our Q-switched Nd-YAG laser we have evaporated different materials (Al, Ti, Pt Au), alloys (Ta-Si) and dielectrics (ZrO2, Al2O3). We also produced sandwich layers (Al-Au, Ti-Al). The layers were investigated with regard to deposition rate, homogeneity, adhesion, step coverage and surface roughness. Deposition rates in the order of 60 nm/min were aschieved. At a power of 10 W and a repetition rate of about 5 kHz we could form ohmic contacts to silicon with a good step coverage in the contact.