Directed self-assembly lithography for half-pitch sub-15 nm pattern fabrication process

This paper introduces a fabrication method to achieve sub-15 nm line-and-space (L/S) patterns by combining grapho- and chemo-epitaxy using poly(styrene-block-methyl methacrylate) copolymer (PS-b-PMMA). The fabrication method is simple, since it eliminates photoresist stripping and also does not require any special materials to form pinning patterns. In this process, the ridges formed on spin-on-glass (SOG) surface work as physical guides and the photoresists on them are utilized as a pinning layer. Fine PS-b-PMMA L/S patterns were obtained in sufficient critical dimension (CD) range of the guide patterns that corresponded to the 15% dose margin using ArF immersion lithography. 3-dimensional grid defects were found to be the origin of the short defects. The half-pitch (hp) 15 nm L/S patterns were transferred successfully to SOG/spin-on-carbon (SOC) stacked substrate. We also describe fabrication of sub-10 nm L/S patterns using a high-chi block copolymer (BCP).