Diamond nanoimprint lithography

Electron beam (EB) lithography using poly methylmethacrylate (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 pm wide and 270 nm deep. The diamond mould was pressed into PMMA on a silicon substrate heated to 130, 150 and 170degreesC at 43.6, 65.4 and 87.2 MPa. All transferred PMMA convex line patterns were 2 mum wide. Imprinted pattern depth increased with rising temperature and pressure. PMMA patterns on diamond were transferred by the diamond mould at 150degreesC and 65.4 MPa, yielding convex line patterns 2 mum 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.