Fabrication of diamond and diamond-like carbon molds for nano-imprinting lithography

Micro- and nano-scale molds were fabricated using nanocrystalline diamond (nano-diamond) and diamond-like carbon (DLC) films for imprinting lithography. Patterning was first transferred to the resist on nano-diamond and DLC thin films by photolithography and imprint lithography methods, and then deep etching with inductively-coupled plasma reactive ion etching (ICP-RIE) was applied to transfer patterns to nano-diamond and DLC films for the fabrication of diamond molds. Nano-diamond films of about 1.5μm in thickness were deposited on silicon substrates by hot filament chemical vapor deposition (HFCVD) by controlling CH₄/H₂ ratios and substrate temperatures. Thick diamond-like carbon films containing silicon oxide nanoparticles were deposited on silicon substrates by PECVD using gaseous HMDSO (Hexamethyldisiloxane) reactants to release the film stress. E-beam writer was used to pattern the resist on the Cr film-covered thick DLC film. By using ICP-RIE, Cr film was first patterned with the patterned e-beam resist as the etching mask, and then DLC thick film was etched to form nanoimprint mold using the patterned Cr as the etching mask. High fidelity nano-patterns were transferred with nano-imprinting lithography using the nano-diamond and DLC molds. Good mold releasing behavior and high mold strength were observed for the nanocrystalline diamond and DLC molds due to their highly hydrophobic surface and high toughness, respectively.