Superconformal copper filling of a nano-scale trench by nucleation suppression at the trench entrance during metal organic chemical vapor deposition

Superconformal filling of copper (Cu) into the nano-scale SiO2 trench was investigated by controlling the nucleation and growth conditions during the metal organic chemical vapor deposition of Cu. Inductively coupled H2/Ar plasma pretreatment of the Ru-deposited trench pattern with a substrate biasing prior to deposition led to suppression of Cu nucleation on the top and entrance areas of the trench. In turn, Cu grows preferentially inside the trench. Controlled nucleation by plasma pretreatment enabled the achievement of superconformal Cu gap filling of sub-60 nm trenches without voids. Suppression of nucleation was attributed to deposition of sputtered silica (Si)-containing species on the top and entrance areas of the trench from the quartz window of the plasma reactor.