Abstract
Low resistivity aluminum films have been deposited by dc bias sputtering without excessive presputtering. Minimum resistivity occurs for a bias (VB) of approximately −40 V and, in contrast to the case for sputtered molybdenum, the resistivity increases for higher negative biases. For as-deposited 6500-Å films, resistance ratios (R.T./4.2 K) greater than 20 were obtained for VB=−40 V, indicating a minimum resistivity within 5% of bulk. Total (tensile) stress for these same films (deposited at substrate temperatures of 120–200 C) is ∼+1.5×109 dyn/cm2 for VB=−40 V, dropping to ∼+0.8×109 dyn/cm2 for VB=−125 to −150 V. The films exhibit an increasingly rougher surface for increasing negative bias, in contrast with sputtered molybdenum films, which show the opposite bias dependence.