Diamond nanoimprint lithography

Abstract

Electron beam (EB) lithography using polymethylmethacrylate (PMMA) and oxygen gas reactive ion etching (RIE) were used to fabricate fine patterns in a diamond mould. To prevent charge-up during EB lithography, thin conductive polymer was spin-coated over the PMMA resist, yielding dented line patterns 2 μ m wide and 270 nm deep. The diamond mould was pressed into PMMA on a silicon substrate heated to 130, 150 and 170ºC at 43.6, 65.4 and 87.2 MPa. All transferred PMMA convex line patterns were 2 μ m wide. Imprinted pattern depth increased with rising temperature and pressure. PMMA patterns on diamond were transferred by the diamond mould at 150ºC and 65.4 MPa, yielding convex line patterns 2 μ m wide and 200 nm high. Direct aluminium and copper patterns were obtained using the diamond mould at room temperature and 130.8 MPa. The diamond mould is thus useful for replicating patterns on PMMA and metals.

Micro-machining of resists on silicon by proton beam writing

“…It was demonstrated that the PBW combined with the electroplating is a promising technique to make stamps for imprint lithography. As previously reported [8], bulk production is possible by means of imprint lithography process with metal stamps [20][21][22][23][24][25].…”

Recent progress in direct patterning technologies based on nano-imprint lithography

“…Because most inorganic thin films have little fluidity, a high imprinting pressure above 1 × 10 7 Pa and an imprinting mold more rigid than the imprinted thin films are needed for the RT-NIL process. Figures 4a and 4b show SEM micrographs of aluminum patterns demonstrated by our group [40], and copper patterns demonstrated by Taniguchi et al [41], respectively. As shown in Figure 4, metal layers with a high ductility like Al and Cu were directly patterned using this RT-NIL technique.…”

Ni electroplating on a resist micro-machined by proton beam writing

“…These data indicate that the micromachined PMMA by PBW can be used as a template for the electroplating. Coupled with the capability of the PBW for structures with high aspect ratio up to 20 (Uchiya et al 2007), the PBW can be a promising tool for making molds with high aspect ratio for imprint lithography process (Hirai et al 2002;Heidari et al 2000;Pfeiffer et al 2002;Taniguchi et al 2002;Schulz et al 2000;Guo 2004).…”