Device fabrication by plasma etching
AssigneeBell Telephone Laboratories, Incorporated
InventorCyril J. Mogab
Life of this patent
Estimating the term…
Abstract
Plasma etching as applied to many of the materials encountered in the fabrication of LSI's is complicated by loading effect--the dependence of etch rate on the integrated surface area to be etched. This problem is alleviated by appropriate choice of etchant and etching conditions. Appropriate choice of system parameters, generally most concerned with the inherent lifetime of etchant species, may also result in improvement of etch rate uniformity on a wafer-by-wafer basis.
Claims24
Process for fabrication of at least one article comprising at least one operation during which the article undergoing fabrication comprises a surface to be etched wherein the said article surface is maintained within a plasma environment contained within an apparatus, the plasma resulting from imposition of an rf electrical field across gaseous matter between two electrodes, the surface to be etched consisting of a composition manifesting a loading effect when etched by a plasma environment produced across a gas mixture consisting essentially of CF.sub.4 and O.sub.2, or CCl.sub.4, the said surface consisting essentially of a composition selected from the group consisting of elemental silicon, elemental aluminum, silicon nitride, boron nitride, and resists utilized in SIC processing, the said loading effect being defined as a variation in etch rate of at least 25 percent for a loading variation of from 10 percent capacity to 100 percent capacity for the said apparatus, etching being primarily due to reaction of the said surface with a primary etchant species characterized in that the said gaseous matter is of composition such as to result in two active chemical species within the said plasma, in which the two species are chemically distinct, the first of which, denoted primary etchant species, reacts with the said surface to result in removal of surface material and the second of which, denoted recombinant species, primarily serves to combine with unreacted primary etchant species to result in the said mean inherent lifetime, and in which the amount of recombinant species is maintained at a level sufficient to reduce mean inherent lifetime of the primary etchant species to a value which is no more than one-tenth as great as the mean lifetime due to chemical reaction with the surface resulting in etching.
Dependencies are inferred from the claim text.