WAT and VBD Distribution Improvement on Low-K Trench All-in-one Process

Abstract

WAT (Wafer Acceptance Test) and VBD (Voltage Breakdown) distribution are not merely a function of critical dimension and oxide thickness as were seen on conventional BEOL process on larger technology node. The complexity of electrical and reliability parameter becomes more on advanced technology node, i.e. 65nm and sub 65nm, as its k value and Cu surface plays some significant role on the parametric distribution result. This study is addressed to improve the WAT and VBD distribution by minimizing the Cu surface and low-k damage, such that the impact to the electrical parameter is small enough that can be negligible, hence the WAT and VBD will be more predictable and controllable. Optimization on this study would be focused on the chemical selection of the PR stripping and PET (Post Etch Treatment) steps, which are the critical steps for low-k and Cu surface damages.