Sequential infiltration synthesis and pattern transfer using 6 nm half-pitch carbohydrate-based fingerprint block copolymer

This study presents how sequential infiltration synthesis of trimethyl aluminium and water into a carbohydrate-based block copolymer was used to enable pattern transfer of 6 nm half-pitch horizontal cylinders into silicon. Specular neutron reflectometry measurements of poly(styrene)-block-maltoheptaose self-assembled into horizontal cylinders indicate an increasing content of alumina after each sequential infiltration cycle, comparing 0, 1, 2, and 4 cycles, with alumina content reaching 2.4 vol% after four infiltrations cycles. Dry etching processes in inductively coupled plasma reactive ion etching for sub-10 nm patterns were developed, using a two-step technique: O2-plasma for polymer removal and a reactive ion etching of Si using a mixture of SF6 and C4F8 gases. Etch selectivity of more than 2:1 of silicon over alumina-like etch mask material was achieved. To evaluate the etching process, the etched Si structures were measured and characterized by scanning electron microscopy. These results are expected to be of use for nanofabrication and applications in the sub-10 nm regime.