The Role of Feedgas Chemistry, SiO sub 2 Mask Material and Neutral/ion Flux Ratio in Feature Profile Evolution During High Density Plasma Etching of Si(100)

Feature evolution of trenches during high density plasma etching with Cl sub 2, HBr, and HCl plasmas are studied. Trenches were etched both with and without an insulating SiO sub 2 mask layer. The independence of profile evolution on mask charging is demonstrated. The role of the SiO sub 2 mask material itself is discussed. During etching without an SiO sub 2 mask, faceting of the silicon is observed. The importance and relevance of this faceting to the profile evolution process is discussed. Similarities between profiles etched with different feedgases under different plasma conditions are noted.