Optimization of 28nm M1 trench etch profile and ILD loss uniformity

Cu process and low-k material are wildly used to reduce Rc delay effect from 45nm technology node and beyond, dry etch to low-k material is one of big challenges in BEOL (Back-End-of-Line) process. For M1 trench etch, the main parameters, such as M1 trench CD, trench depth, trench profile, trench ILD loss uniformity and the connection between M1 & CT, will impact the result of M1 WAT (Rs and Capability) and Reliability. In this article the optimized trench profile and ILD loss uniformity for 28nm M1 etch was obtained by balancing various dry etch process parameters.