Microlithography 1993
Conference paper

170 nm gates fabricated by phase-shift mask and top anti-reflector process

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N-channel Field Effect Transistors (EETs) with poly linevvidths as small as 17()nm have been fabricated with phase shift mask (PSM) lithography using a 0.45 NA I-line stepper. Narrow poly lines were defined using the edge of a it shifter rectangle with superimposed chrome lines of variable width to produce a range of linewidths. Using a chrome-less phase edge, resist linewidths of 24()nm were obtained at nominal exposure, while + 25% overexposure yielded linewidths of 190nm. Excellent linewidth control was obtained on the device wafers with 3σ variation of roughly 20nm for the resist lines. The use of a Top Anti-Reflector (TAR) process improved linewidth control by approximately 35% relative to a normal single layer resist process. Linewidths were also measured after poly etch and, in the final devices, Leff was measured by electrical testing. Devices fabricated using PSM showed significant improvement in lithographic process latitude over control devices fabricated using conventional chrome masks.