Resist features as small as 200 Aring; and gold lines as narrow as 400 Aring; separated by 800hyphen;Aring; center to center have been fabricated on thick silicon. substrates. A twohyphen;layer electronhyphen;sensitive resist structure is employed consisting of an upper layer of polymethylhyphen;methacrylate and a lower layer of a copolymer of methacrylic acid and methyl methacrylate. Use of the more electronhyphen;sensitive lower layer results in an undercut which provides clean lifthyphen;off of the evaporated gold. Degradation in the pattern resolution by electrons backscattered from the substrate is minimized by the presence of the lower resist layer. This method provides the finest resolution lifthyphen;off patterns reported.
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