Methods of forming openings and methods of controlling the degree of taper of openings

Abstract

Methods of forming contact openings and methods of controlling the degree of taper of contact openings are described. In one implementation, a layer is first etched through a contact mask opening using a first set of etching conditions. The etching conditions provide a first degree of sidewall taper from vertical, if etching completely through the layer. After the first etching, the layer is second etched through the contact mask opening using a second set of etching conditions. The second set of etching conditions provide a second degree of sidewall taper from vertical, if etching completely through the layer. The second degree of sidewall taper is different from the first degree of taper. In another embodiment, a material through which a contact opening is to be etched to a selected depth is formed over a substrate. A masking layer having an opening therein is formed over the material. The material is first etched through the opening with the first etch having a first selectivity relative to the masking layer. After the first etch, and at a depth which is less than about 50% of the selected depth, the material is second etched, with the second etch having a second selectivity relative. to the masking layer which is greater than the first selectivity. In a preferred implementation, the second degree of selectivity is achieved by modifying an etch parameter during the etching of the contact opening.