Direct Copper Electrochemical Deposition on Ru-Based Substrates for Advanced Interconnects Target 30 nm and 1/2 Pitch Lines: From Coupon to Full-Wafer Experiments

Extending copper electrochemical deposition to 3x nm nodes and beyond requires a new plating approach that is not constrained by typical PVD copper seed step coverage performance. To this purpose, we propose a copper direct plating process on Plasma Enhanced Atomic Layer Deposition (PEALD) Ru-based resistive substrates, where the Cu seed is deposited in-situ during the front propagation from the edge to the center of the wafer. In order to understand the full-wafer copper direct plating process that occurs on these liners, the effect of plating tool advanced features, applied waveform, plating chemistry and substrate surface activation on the subsequent plated copper nucleation behavior are studied.