Chemical Semi-Amplified Positive E-Beam Resist CSAR 62 for Highest Resolution

摘要

Positive-tone poly(methyl methacrylate) (PMMA) e-beam resists have already been applied for decades in electron beam lithography. While these resists are characterised by high process stability, their sensitivity, contrast and plasma etch stability must be regarded as comparatively low. A significant improvement of sensitivity and plasma etch stability can be achieved with e-beam resists on the basis of α-methyl styrene a-chloromethacrylate copolymers (e.g. ZEP 520) that are also perfect candidates for preparation of undercut architectures for lift-off applications. Main disadvantage of these resists however is a low commercial availability. On the other hand, chemical amplified resist (CAR) systems are known which show a one order of magnitude higher sensitivity than conventional e-beam resists, but the resolution of these resists is limited due to diffusion processes inherent to the chemical amplification.