document: As the progression towards smaller lithographic nodes continues it has become necessary to adopt thinner resist films to mitigate problems such as pattern collapse. To address the issue of reduced etch resistance of thin photoresist films the semiconductor industry has begun to develop multilayer processes where the pattern is first transferred into an intermediate organic hardmask with higher etch selectivity before final silicon pattern transfer [25–27]. In this paper we demonstrate how the introduction of such a multilayer process can also benefit nanosphere lithography by increasing achievable aspect ratios of silicon nanopillars without the need for complex etch processes requiring specialised and expensive equipment, but instead needing only a standard SF6/C4F8 inductively coupled plasma (ICP) mixed mode etch process at room temperature [28]. As intermediate layer material we used polyimide, which finds widespread use as encapsulation material for IC production. It is readily patterned in oxygen plasma and has a lower etch rate than silicon in SF6 gas. Its flexibility can also be used for the fabrication of soft polymer pillars by the same process as we will show. The multilayer process slightly increases the complexity of sample preparation but allows basic ICP etching to achieve high aspect ratio structures at smaller feature sizes that previously reported without the need for complex etching equipment.
doc_bio_tags: O O O O B I I O O O O O O O B I I O O O O O B I O O O O O B I I I I I I O O O O O O O B I O O O O O O O O B I I O O O O O O B O O O O O O O O O O O O O O B I O O O B I O O O O O O B O O O O O B I I O O O O O O O O O O O O O B I B O O O O O O O O O B I I O O B O O O O O B I O B I O O O O O B I O O O O O O O B O B I O O O O O O O O B I I I I O O O O O O O O O B I O O O O O B I O O O B O O O O O O O O O O O O O O O O O O O B I
extractive_keyphrases: complex etch processes coupled plasma encapsulation material etching equipment fabrication of soft polymer pillars icp ic production intermediate layer material intermediate organic hardmask multilayer process multilayer processes nanosphere lithography oxygen plasma pattern collapse polyimide reduced etch resistance of thin photoresist films sample preparation sf6 gas silicon smaller lithographic nodes thinner resist films
abstractive_keyphrases: icp etching silicon nanopillars silicon pattern transfer thin photoresist films