Method of etching dielectric layers using a removable hardmask

Abstract

A method of patterning a layer of dielectric material having a thickness greater than 1,000 Å, and typically a thickness greater than 5,000 Å. The method is particularly useful for forming a high aspect ratio via or a high aspect ratio contact including self-aligned contact structures, where the aspect ratio is typically greater than 3 and the feature size of the contact is about 0.25 &mgr;m or less. In particular, an organic, polymeric-based masking material is used in a plasma etch process for transferring a desired pattern through an underlying layer of dielectric material. The combination of masking material and plasma source gas must provide the necessary high selectivity toward etching of the underlying layer of dielectric material. The selectivity is preferably greater than 3:1, where the etch rate of the dielectric material is at least 3 times greater than the etch rate of the organic, polymeric-based masking material. The dielectric material may be inorganic, for example, silicon oxide; doped silicon oxide; carbon-containing silicon oxide; SOG; BPSG; and similar materials. The dielectric material may be also be organic, where a high temperature organic-based masking material is used for transferring a desired pattern, and the underlying dielectric material is of a chemical and structural composition which is sufficiently different from the masking material that the required selectivity is provided. In any case, the organic, polymeric-based masking material is easily removed from the substrate etch process after completion of etch without damage to underlying device structures.