Patent ID: 6291359
Filing Date: 2001-09-18
Classification: H01L

Abstract:
A method of controlling the degree of taper of an opening formed in a material, comprising:forming a layer of material into which an opening having a first depth is to be etched;forming a masking layer over the layer of material;exposing a portion of the layer of material through the masking layer;conducting a first dry etch of the exposed portion of the layer of material utilizing a first etch chemistry having a first degree of selectivity relative to the masking layer, the first etch chemistry comprising a first ratio of carbon to fluorine to provide a first degree of selectivity relative to the masking layer;at a second depth which is about 50% or less of the first depth, modifying the first etch chemistry to provide a second dry etch chemistry, the second dry etch chemistry comprising a second ratio of carbon to fluorine to provide a second degree of selectivity relative to the masking layer, the second ratio being lower than the first ratio and the second degree of selectivity being greater than the first degree of selectivity;conducting a second dry etch of the layer of material down to the first depth using the second etch chemistry; andthe opening having a sidewall and a degree of taper along a majority of the sidewall which is no greater than about 3-degrees away from vertical; the first etch chemistry generating a first degree of the taper of the sidewall from vertical and the second dry etch chemistry generating a second degree of the taper of the sidewall from vertical; the first degree of the taper of the sidewall being less than the second degree of the taper of the sidewall.