Development of a table top Nanopatterning tool with Extreme Ultraviolet laser illumination

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

Barcelona

Conferencia; 32nd International Conference on Micro and Nano Engineering. 17-21 September (2006); 2006

We have demonstrated the capabilities of a table top nanopatterning system based on the illumination with compact extreme ultraviolet (EUV) laser sources to print nanoscale arrays of lines and dots on photosensitive resists. The high brightness and coherence of the compact sources are exploited in two patterning schemes: (a) imaging using diffractive optics and (b) interferometric lithography (IL). Results using a 47 nm table top laser demonstrated nanopatterning of lines and dots over relative extended areas (50x50 microns) in short (few seconds) exposure times. The imaging setup set up is schematically represented in Figure 1. A mask with the desired pattern is Illuminated with the output from the EUV laser and its image is formed onto a resist-coated substrate using a zone plate. We tested this scheme using a self standing zone plate 500 µm in diameter, 625 zones of outermost zone width of 200 nm. This zone plate has a focal length of 2.14 mm at 47 nm with a depth of focus of 1.7 µm. With this focusing optics the expected spatial resolution is limited to 200 nm. An image of a grid pattern obtained with 3 seconds exposure using the 47 nm EUV laser is shown in Figure 2. The imprinted dots have a diameter 380 nm. This method demonstrated to be very effective to produce large arrays of dots over a relative extended area (50x50 um2) with a simple set up and extremely short exposure times. The high coherence of the 47 nm laser, controlled by adjusting the gain medium length, also favours patterning by interference. In a previous experiment we performed a proof-of-principle experiment utilizing a Lloyd’s mirror to imprint lines with period as small as 55nm in a Si wafer coated with PMMA. Figure 3 shows a typical pattern of parallel lines obtained in this experiment with a period of 92 nm. The high degree of spatial coherence degree and the high photon flux of the 47 nm capillary discharge laser offers interesting alternatives for the interferometric lithography with relative large area coverage that will also be discussed