Micro- and nano-patterns fabricated by embossed microscale stamp with trenched edges

Abstract

A submicron width of Au line patterns was fabricated from a polydimethylsiloxane (PDMS) line stamp of micron width by utilizing capillary-force and edge-transfer lithography (ETL). A template composed of Al(OH)₃ was fabricated by capillary-force lithography (CFL) carried out by KOH ink-loaded microscale PDMS stamping on an Au nanomembrane (30 nm)-deposited Al thin layer (50 nm) on a glass substrate. Because the Au nanomembrane works as an OH⁻ ion channel, protruding Al(OH)₃ micro-structures are obtained by a pH-dependent molding process reacting underneath the Al thin layer. The protruding Al(OH)₃ template has sharp edges at the molding area resulting from the capillary force working on the walls of the molding PDMS stamp and aqueous Al(OH)₃ solution during the molding process. For example, the highest and widest ring edges of the protruding Al(OH)₃ fabricated by a dot PDSM stamp (ϕ: 4.5 μm, gap: 3 μm) are obtained through a molding time of 20 min with 1 M KOH ink. The protruding Al(OH)₃ micro-structures were used as templates to fabricate dot and line PDMS stamps. The replicated PDMS stamps have deep trenches around the contact area of the stamps; thus, the replicated PDMS stamp has an advantage of holding ink solution in the recessed space. Through (ETL) with a replicated line PDMS stamp, which has deep trenches around the line shape contact area, an Au line-pattern array of 700 nm in width was fabricated by 16-mercaptohexadecanoic acid (MHA) patterning on Au/Ti (30 nm/5 nm)-deposited silicon substrate and sequential Au etching for 20 min. In this study, we successfully demonstrated that an advantageous PDMS stamp for (ETL) is obtained by a solid Al(OH)₃ template fabricated by Au nanomembrane-based CFL.