A study of 65nm BEOL trench etch issues

65 nm BEOL trench etch is apt to suffer the marginal PR issue. It is a big challenge for trench etch process to simultaneously satisfy the requirements for both metal resistance (Rs) and breakdown Voltage (VBD). The copper surface condition of via bottom is a big concern of trench etch process as well. In this paper, we present several electrical parameter issues that occurred at 65 nm trench etch process such as Rs, via resistance (Rc) and VBD. The feasible solutions and related etching mechanisms are also addressed for the above issues from the point view of the improvement of line-edge roughness (LER), within wafer AEI CDU (critical dimension uniformity) and interface conditions of via-bottom.