Characterization of ion tracks in PMMA for single ion lithography
No Thumbnail Available
The ultimate resolution in ion beam lithography (IBL) can be achieved by etching tracks modified by the passage of a single ion impact which has a diameter in the order of 10 nm. For precise counting of single ions, a Si photodiode is used as a substrate onto which a PMMA film is spun. We have macroscopically investigated the sensitivity of PMMA using 3 MeV H end found that a deposited energy density of greater than 1 eV/nm(3) is required to remove the PMMA film for 60 s developing in a water:IPA 1:4 solution. From this sensitivity measurement we have determined that 8 MeV F, 71 MeV Cu and 88 MeV I ions should produce enough damage in a single ion strike to create a hole etched along the latent damage track. We have used AFM imaging to quantitatively characterise the hole diameter as a function of the incident ion and the developing time. It was found that for up to 8 min development in a water:IPA solution holes were created for the F, Cu and I ions. SEM imaging has also been used to verify the holes seen by AFM imaging. © 2007, Elsevier Ltd.
Ions, PMMA, Ion beams, Resolution, Energy, Etching
Alves, A., Johnston, P. N., Reichart, P., Jamieson, D. N., & Siegele, R. (2007). Characterization of ion tracks in PMMA for single ion lithography. Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 260(1), 431-436. doi:10.1016/j.nimb.2007.02.058