Effects of CH[sub 2]F[sub 2] Addition on a High Aspect Ratio Contact Hole Etching in a C[sub 4]F[sub 6]/O[sub 2]/Ar Plasma

An contact hole with a diameter of 0.17 μm and an aspect ratio of 15 was etched in and plasmas, and the effects of gas on the etch profiles and the etch selectivity to photoresist were investigated. The addition of gas enhanced the production of fluorocarbon films by reactive C-F species, resulting in more fluorocarbon films deposited on the photoresist layer and the sidewalls of the contact hole compared to the gas being absent. This finally led to drastic improvements in the critical dimension loss and the etched contact profiles. The etch selectivity to photoresist was also enhanced in the presence of gas due to hydrogen atoms as well as reactive C-F species. X-ray photoelectron spectroscopy analyses showed that the fluorocarbon films produced in the plasma were more carbon-rich compared to those in the plasma.