Self-Assembled Monolayer of 3-N, N-Dimethylaminodithiocarbamoyl-1-Propanesulfonic Acid (DPS) Used in Electrodeposition of Copper

This paper reports an experimental investigation of 3-N, N-dimethylaminodithiocarbamoyl-1-propane sulfonic acid (DPS) additive behavior attached to copper as a self-assembled monolayer (SAM) prior to electrodeposition of copper. Rotating disk electrode (RDE) voltammetry and linear sweep cyclic voltammetry (LSCV) revealed that the extent of derivatization of a Cu electrode is time-dependent and it can be controlled. The monitoring of copper deposition rate for 25 min on DPS-SAM derivatized electrode in PEG and DPS free electrolyte plating solution indicates that DPS-SAM remains attached at the electrode surface. It was demonstrated that the deactivation of DPS-SAM on Cu RDE during Cu deposition in acidic copper electrolyte (Cu +2 + PEG + Cl − ) without DPS is dependent the on potential and rotation rate of the RDE. The superfilling of trenches with different width (0.5 μm and 50 μm) was demonstrated using a two-step process including DPS-derivatization of Cu seed layer on 6 inch patterned wafers, followed by copper electrodeposition.