Plasma-surface interactions of advanced photoresists with C4F8∕Ar discharges: Plasma parameter dependencies

One recurring problem in nanoscale processing is roughening of photoresist (PR) materials during plasma etch. We studied the plasma etch behavior of 248nm PR, 193nm PR, and poly methyladamantyl methacrylate while changing the source power level (400–1200W), adjusting the bias power to change the self-bias voltage Vdc (−50to−150V), and varying the pressure (10–80mTorr) and the amount of fluorocarbon gas additive to the Ar discharge (0%–10% c-C4F8 in Ar). The authors found that the PR removal is dominated by the ion energy and fluence. Surface fluorination enhanced the removal rates. Two linked mechanisms for the roughening behavior of the films during processing were identified. Changes of PR top surface roughening behavior in response to variations of bias power and pressure could be interpreted by a model of roughness formation which is dominated by a physical pattern transfer mechanism, i.e., roughness amplification through selective ion-induced transfer. When the plasma source power was varied, they ob...

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