Effect of Cu contamination on electrical characteristics for PMOS transistors

Abstract

PMOS transistors of various (W/L) ratios down to 0.24μm channel length have been used to investigate the effect of copper diffusion on their electrical parameters. A thin layer of copper film was deposited on the back of the wafer. Over 13.5 hours of annealing at 400°C was carried out. Electrical parameters such as the threshold voltage (VT0) and the transconductance (Gm) for transistors, and the leakage current for large diodes were measured. Secondary Ion Mass Spectroscopy (SIMS) was used to monitor the copper diffusion. Even after 13.5 hours of annealing at 400° C, electrical parameters of PMOS devices showed no significant degradation.