Reliability of thin gate oxide under plasma charging caused by antenna topography-dependent electron shading effect

This paper reports on the effect of plasma charging due to antenna-topography-dependent electron shading effect during metal etching on thin gate oxide in the thickness range of 2.2 to 6.0 nm. It is shown that, down to 3.5 nm, oxide reliability degrades with decreasing oxide thickness. Oxide thinner than this, however, shows improved resistance to plasma charging. A method is proposed for quantifying the charging damage in terms of the charge trapped in the oxide. An explanation is given for the oxide thickness dependence of the charging damage. This permits quantitative estimation of the impact of the topography-dependent charging on reliability and design of future scaled-down MOS devices. Consequently, a design guideline for reliable LSIs can thereby be determined.