ION TRAJECTORY DISTORTION AND PROFILE TILT BY SURFACE CHARGING IN PLASMA-ETCHING

Surface charging effects on etching profiles during silicon etching in a nonuniform plasma were investigated by scanning electron micrograph s and plasma potential measurements. The distortion in ion trajectorie s caused by the surface charging was calculated by an ion lens simulat or. A tilt in the etching profile was found in holes and trenches near a large etched area when an insulating mask such as photoresist or si licon dioxide was used. Ion trajectory calculations showed that this p rofile tilt was caused by the local electric field resulting from the potential difference between the charged mask surface and the electric ally grounded silicon substrate. This profile result agrees well with gate oxide damage results which were also successfully explained by su rface charging.