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RALPH R. DAMMEL, Clariant Corporation, Somerville, NJ, USA

ABSTRACT

The history of lithography in the last two decades has been dominated by the extension of the life of optical technologies. The scope of this extension has exceeded the predictions of almost any expert bold enough to forecast the development of exposure techniques in the early 1980s, when questions about the future of optical lithography were first raised. Optical technology has been instrumental in keeping the industry on the well known Moore’s law curve [1] which, in its present incarnation, states that the storage density of memory chips doubles every 18 months (Figure 1). Improvements in i-line technology have pushed classic DNQ/novolak systems far beyond the “submicron barrier” for which some experts had first predicted the imminent demise of the optical techniques. Today, the combination of high-performance i-line resists with high-NA steppers has extended the range of i-line lithography to quarter-micron final resolution (Figure 2). Quarter-micron DUV (248 nm) lithography is commonplace, and advanced processes are moving from 180 nm to 150 nm feature sizes.