Electron irradiance of conductive sidewalls: A determining factor for pattern-dependent charging

Numerical simulations of charging and profile evolution during gate electrode overetching in high density plasmas have been performed to investigate the effect of long conductive sidewalls on profile distortion (notching). The results reveal that the angle of electron irradiance of the conductive portion of the sidewalls affects profoundly the charging potential of the gates. Larger angles, obtained for thinner masks and/or thicker polysilicon, result in reduced gate potentials which, through their influence on the local ion dynamics, cause more severe notching at all lines of the microstructure