title: Low-temperature plasma etching of high aspect-ratio densely packed 15 to sub-10 nm silicon features derived from PS-PDMS block copolymer patterns.
abstract: The combination of block copolymer (BCP) lithography and plasma etching offers a gateway to densely packed sub-10 nm features for advanced nanotechnology. Despite the advances in BCP lithography, plasma pattern transfer remains a major challenge. We use controlled and low substrate temperatures during plasma etching of a chromium hard mask and then the underlying substrate as a route to high aspect ratio sub-10 nm silicon features derived from BCP lithography. Siloxane masks were fabricated using poly(styrene-b-siloxane) (PS-PDMS) BCP to create either line-type masks or, with the addition of low molecular weight PS-OH homopolymer, dot-type masks. Temperature control was essential for preventing mask migration and controlling the etched feature's shape. Vertical silicon wire features (15 nm with feature-to-feature spacing of 26 nm) were etched with aspect ratios up to 17 : 1; higher aspect ratios were limited by the collapse of nanoscale silicon structures. Sub-10 nm fin structures were etched with aspect ratios greater than 10 : 1. Transmission electron microscopy images of the wires reveal a crystalline silicon core with an amorphous surface layer, just slightly thicker than a native oxide.
authors: Molecular Foundry,1 Cyclotron Road, Berkeley, CA 94720, USA. Oxford Instruments, 300 Baker Avenue, Suite 150, Concord, MA 01742, USA.
authors: Zuwei
authors: Z
authors: Liu
authors: Xiaodan
authors: X
authors: Gu
authors: Justin
authors: J
authors: Hwu
authors: Simone
authors: S
authors: Sassolini
authors: Deirdre L
authors: DL
authors: Olynick
mesh_terms: D003080:Cold Temperature; D004129:Dimethylpolysiloxanes / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D036103:Nanotechnology / Q000379:methods; D009757:Nylons / Q000737:chemistry*; D010316:Particle Size; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry*; D012825:Silicon / Q000737:chemistry*; D012833:Siloxanes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D004129:Dimethylpolysiloxanes; D009757:Nylons; D011108:Polymers; D011137:Polystyrenes; D012833:Siloxanes; C085707:poly(dimethylsiloxane)-polyamide copolymer; D012825:Silicon