Planarized Via-Hole Filling with Molybdenum by Bias Sputtering

Via-hole filling and surface planarization (planarized via-hole filling) were achieved by molybdenum (Mo) bias sputtering under high (∼80%) resputtering, i.e., high (∼ -600 V) substrate bias voltage, conditions. It was shown that Mo redeposition on the via-hole side walls from the via-hole bottom in the early film deposition stages and Mo redeposition on the bottom from the side walls in the latter film deposition stages played an important role in planarized via-hole filling. Planarized via-hole filling, without sputter-induced damage, was achieved by changing the substrate bias in two steps. The first step was thin layer deposition at a lower substrate bias, to protect the Si substrate surface from severe sputter-etching. The second step was planarized via-hole filling at a higher substrate bias.