Abstract: A process for selectively plasma etching polycrystalline silicon or polysilicon in preference to silicon dioxide which minimizes the detrimental effect of carbon. It has been discovered that carbon from the plasma etch chemicals or from photoresist present interferes disadvantageously with the selective plasma etch of polysilicon as opposed to silicon dioxide. By heat treating and deep ultraviolet light treating the photoresist prior to the plasma etch step and by using non-carbon etch chemicals, this detrimental carbon effect can be reduced.

Abstract: This disclosure relates to a process for etching polycrystalline silicon in preference to single crystal silicon. Polycrystalline silicon is anisotropically etched in a plasma which inclues a noncarbonaceus silicon etching compound such as chlorine together with about 0.4-1.5 percent by volume of oxygen. The process is used to fabricate semiconductor devices which require the etching of polycrystalline silicon in the presence of exposed monocrystalline silicon.

Abstract: A method for etching multi-layer structures particularly suited for patterning refractory metal silicide/polysilicon sandwiches. A first dry etch process is carried out in a first dry etch chamber and is selected to rapidly and anisotropically etch the uppermost layer, typically a refractory metal silicide. A second dry etch process is carried out in a second etch chamber and is selected to rapidly and anisotropically etch the underlying layer, typically polysilicon, while having a high selectivity to any material underlying the underlying layer. The first process is preferably a fluorine-chemistry process with low frequency RF energy and the substrate resting on the grounded electrode. The second process is preferrably a chlorine-chemistry process with high frequency RF energy and the substrate resting on the powered electrode.