Post CMP Wet Cleaning Influence on Cu Hillocks

Up to date, it is commonly reported in literature that the amount of copper hillocks is dependent on a) the total amount of residual Cu oxide after Cu CMP, and b) the Cu nitridation. The present work describes how that is only partially true: hillocks depend also on the kind of oxide and on the roughness of the surface after wet treatment. This contribution is even more important than what reported in literature. A tentative model for this behavior is proposed.