In this article, etching of subquarter-micron contact holes with a him structure of silicon dioxide (SiO2)/silicon nitride (Si3N4)/silicide (TiSix) in dual-frequency capacitively coupled plasmas is investigated. The etch process scheme here uses a highly selective chemistry to remove SiO2 film first, then the process switches to another chemistry with high etch selectivity of Si3N4-to-TiSix. The author found that the polymer film deposited inside contact holes during SiO2 etching severely degraded the selectivity of Si3N4-to-TiSix. This can cause open or high contact resistance. Different process integration schemes with the goal of increasing the etch selectivity of Si3N4-to-TiSix were initiated and developed. Electrical parametric data of contact chain resistance will be presented.