THE CONTROL OF PLASMA ETCH SELECTIVITIES VIA OXYGEN ADDITION TO CHLORINE-BASED PLASMAS
Original Publication Date: 1984-Apr-01
Included in the Prior Art Database: 2001-Oct-12
It has been found that the addition of oxygen to a chlorine plasma affects the etch rate ratios of polysilicon-to-titanium silicide-to-silicon dioxide as shown in the attached figure. High etch rate ratios are required in applications where it is necessary to etch polysilicon down to thin gate oxide, or where polysillcon must be etched while titanium silicide is exposed. The mechanism for the etch rate differences of the various materials is thought to be related to their varying oxidation affinities. Thus the etch rate of an easily oxidized material, such as a titanium containing compound, would be lower due to "oxide" formation than a less easily oxidized material such as silicon.