To investigate the ultimate resolution in ion beam lithography (IBL) the resist material poly(methyl methacrylate) PMMA has been modified by single ion impacts. The latent damage tracks have been etched prior to imaging and characterisation. The interest in IBL comes from a unique advantage over more traditional electron beam or optical lithography. An ion with energy of the order of 1 MeV per nucleon evenly deposits its energy over a long range in a straight latent damage path. This gives IBL the ability to create high aspect ratio structures with a resolution in the order of 10 nm. Precise ion counting into a spin coated PMMA film on top of an active substrate enabled control over the exact fluence delivered to the PMMA from homogenously irradiated areas down to separated single ion tracks. Using the homogenous areas it was possible to macroscopically measure the sensitivity of the PMMA as a function of the developing parameters. Separated single ion tracks wer e created in the PMMA using 8 MeV F, 71 MeV Cu and 88 MeV I ions. These ion tracks were etched to create voids in the PMMA film. For characterisation the tracks were imaged primarily with atomic force microscopy (AFM) and also with scanning electron microscopy (SEM). The series of studies presented here show that the sensitivity of the resist-developer combination can be tailored to allow the etching of specific single ion tracks. With the ability to etch only the damage track, and not the bulk material, one may experimentally characterise the damage track of any chosen ion. This offers the scientific community a useful tool in the study and fabrication of etched ion tracks. Finally work has been conducted to allow the precise locating of an ion beam using a nanoscale mask and piezoelectrically driven scanning stage. This method of beam locating has been trailed in conjunction with single ion detection in an effort to test the practical limits of ion beam lithography in the single ion realm.
| Identifer | oai:union.ndltd.org:ADTP/210262 |
| Date | January 2008 |
| Creators | Alves, Andrew David Charles, aalves@unimelb.edu.au |
| Publisher | RMIT University. Applied Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | http://www.rmit.edu.au/help/disclaimer, Copyright Andrew David Charles Alves |
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