Reduction of whisker-originated short between W polymetal and contact plug

摘要

Whisker-originated short in the self-aligned contact (SAC) W polymetal gate was directly observed for the first time.Short points between gate electrodes and poly-Si plugs in the test structure were identified by emission microscope and cross-sectional TEM samples of those points were made by using focused ion beam (FIB).Whiskers are formed during high-temperature processing such as LP-CVD SiN.We have proposed that NH_3 de-oxidation step inserted in the SiN deposition sequence is effective for suppressing whisker growth.In this study it was also confirmed that 600degC NH_3 pre-flow improved leakage current between gate electrode and contact plugs.