TY - JOUR
T1 - Lithography exposure characteristics of poly(methyl methacrylate) (PMMA) for carbon, helium and hydrogen ions
AU - Puttaraksa, Nitipon
AU - Norarat, Rattanaporn
AU - Laitinen, Mikko
AU - Sajavaara, Timo
AU - Singkarat, Somsorn
AU - Whitlow, Harry J.
N1 - Funding Information:
This work was supported the Academy of Finland, The OSKE organisation, Centre of Excellence in Nuclear and Accelerator Based Physics , ref. 213503 and grant 129999 . RN was supported by a CIMO Fellowship. HJW is grateful for travel support from the Magnus Erhnrooth Foundation, which made this work possible.
PY - 2012/2/1
Y1 - 2012/2/1
N2 - Poly(methyl methacrylate) is a common polymer used as a lithographic resist for all forms of particle (photon, ion and electron) beam writing. Faithful lithographic reproduction requires that the exposure dose, Θ, lies in the window Θ0≤Θ<Θ× 0, where Θ0 and Θ× 0 represent the clearing and cross-linking onset doses, respectively. In this work we have used the programmable proximity aperture ion beam lithography systems in Chiang Mai and Jyväskylä to determine the exposure characteristics in terms of fluence for 2 MeV protons, 3 MeV 4He 2+ and 6 MeV 12C3 + ions, respectively. After exposure the samples were developed in 7:3 by volume propan-2-ol:de-ionised water mixture. At low fluences, where the fluence is below the clearing fluence, the exposed regions were characterised by rough regions, particularly for He with holes around the ion tracks. As the fluence (dose) increases so that the dose exceeds the clearing dose, the PMMA is uniformly removed with sharp vertical walls. When Θ exceeds the cross-linking onset fluence, the bottom of the exposed regions show undissolved PMMA.
AB - Poly(methyl methacrylate) is a common polymer used as a lithographic resist for all forms of particle (photon, ion and electron) beam writing. Faithful lithographic reproduction requires that the exposure dose, Θ, lies in the window Θ0≤Θ<Θ× 0, where Θ0 and Θ× 0 represent the clearing and cross-linking onset doses, respectively. In this work we have used the programmable proximity aperture ion beam lithography systems in Chiang Mai and Jyväskylä to determine the exposure characteristics in terms of fluence for 2 MeV protons, 3 MeV 4He 2+ and 6 MeV 12C3 + ions, respectively. After exposure the samples were developed in 7:3 by volume propan-2-ol:de-ionised water mixture. At low fluences, where the fluence is below the clearing fluence, the exposed regions were characterised by rough regions, particularly for He with holes around the ion tracks. As the fluence (dose) increases so that the dose exceeds the clearing dose, the PMMA is uniformly removed with sharp vertical walls. When Θ exceeds the cross-linking onset fluence, the bottom of the exposed regions show undissolved PMMA.
KW - MeV ion beam lithography
KW - PMMA
KW - PPAL
KW - Proton beam writing
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U2 - 10.1016/j.nimb.2011.01.056
DO - 10.1016/j.nimb.2011.01.056
M3 - Article
AN - SCOPUS:84655168022
VL - 272
SP - 162
EP - 164
JO - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
JF - Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms
SN - 0168-583X
ER -