Plasma Technology for Advanced Devices
Volume 11: Sepember 2003
Plasma Etching: Dielectric Materials
“Effects of CH2F2 Addition on a High Aspect Ratio Contact Hole Etching in a C4F6/O2/Ar Plasma”
The profile / CD control and resist selectivity for etching of 0.17 μm contact holes (TEOS, DUV resist) with 15:1 aspect ratio were studied as a function of CH2F2 addition to a C4F6 based chemistry. The experiments were performed in a MERIE reactor at 45 mTorr, 1800 W, 100 G. SEM cross sections show a thicker fluorocarbon passivation film for the CH2F2 added chemistries. A reduction in sidewall bowing is observed when the CH2F2 flow was increased. For a flow of 20 sccm CH2F2, sidewall bowing is virtually absent and the resist selecctivty is increased from 3.8 to 5.8. XPS analysis shows that the fluorocarbon films on oxide were carbon-rich in the presence of CH2F2 gas.