Printing arrays of nano-holes with EUV compact Lasers

M. G. CAPELUTO; P.W. WACHULAK; M.C. MARCONI; D. PATEL; C.S. MENONI; J.J. ROCCA; C. IEMMI; E.H. ANDERSON; W. CHAO; D.T. ATTWOOD

Mar del Plata

Simposio; 4th Latin-American Symposium on Scanning Probe Microscopy; 2007

A table top nanopatterning tool was developed to print arrays of nano-holes. This tool exploited the illumination capabilities of a compact 46nm extreme ultraviolet (EUV) laser[1,2]. The capillary discharge laser is capable of generating coherent EUV radiation with an average power of few mW at repetition rates up to 10 Hz. Several photo-lithography schemes where used for this experiment. a) The first approach was de-magnifying imaging using a diffractive zone plate and a mask with a hole-array pattern. b) In a second approach interferometric lithography with a Lloyd’s mirror was used to produce 2D patterns combining multiples exposures. We performed in a previous work a proof-of-principle experiment utilizing a Lloyd’s mirror to imprint lines with period as small as 55 nm in a Si wafer coated with PMMA. In this work we print two orthogonal line patterns to produce an array of holes or pillars depending on the applied dose. c)The third approach is multiple beam interferometric lithography. Four diffraction gratings situated on the edges of a 50 µm square produced four coherent beams that were used to generate a multiple beam interferometric pattern. With these three approaches, arrays of holes and pillars were printed covering large areas in a PMMA silicon coated wafer. The patterns were read using an AFM in tapping mode. Features with sizes ranging from 370nm down to 60nm were observed with a modulation depth limited by the penetration length of the resist(about 30nm for this wavelength).