The damage-free flattening technology of a Si wafer that using a numerically controlled local dry etching (NC-LDE) technology has been developed to meet the requirement for achieving an extremely flat-surface wafer for the downscaling of ULSI feature size. In this technology, fluorine atoms which are generated in a localized SF_6 downstream plasma are exposed at a local area of a Si wafer, thereby generating a high etch rate of 130μm/min at the bottom of the etched profile and a volume removal rate of 45.9(mm)^3/min. The flattening process was carried out by numerically controlled scan etching according to previously measured thickness data and consequently maximum site flatness was improved from 0.12μm to 0.04μm within 310s for a 300-mm-diameter. Some applications of NC-LDE are reported in this paper.
