| AVS 63rd International Symposium & Exhibition | |
| Advanced Ion Microscopy Focus Topic | Thursday Sessions |
| Session HI+NS-ThM |
| Session: | Fundamentals of Ion Beam Microscopy |
| Presenter: | Ing-Shouh Hwang, Institute of Physics, Academia Sinica, Taipei, Taiwan, Taiwan, Republic of China |
| Authors: | I.S. Hwang, Institute of Physics, Academia Sinica, Taipei, Taiwan, Taiwan, Republic of China W.T. Chang, Institute of Physics, Academia Sinica, Taipei, Taiwan W.C. Lai, Institute of Physics, Academia Sinica, Taipei, Taiwan P.-C. Li, Institute of Physics, Academia Sinica, Taipei, Taiwan T.Y. Fu, Department of Physics, National Taiwan Normal University, Taipei, Taiwan T.T. Tsong, Institute of Physics, Academia Sinica, Taipei, Taiwan |
| Correspondent: | Click to Email |
Current focused ion beam systems are mainly equipped with liquid metal ion sources (LIMSs). Even though LMISs are very reliable in operation, their relatively large source size and high energy spread limit the current density. In contrast, gas field ion sources(GFISs) can reach higher beam currents at smaller beam diameters because of their atomic-scale source size and a small energy spread (<1 eV). Since 2006, Zeiss Orion helium ion microscope (HIM) has demonstrated superior performance with a spatial resolution better than 0.5 nm [1]. To expand the application of GFISs, it is essential to develop GFISs of various ion species, particularly, ions of high mass.
Here we present Xe-GFIS emitted from a noble metal covered W(111) single-atom tip (SAT) [2,3]. This type of SATs are thermally and chemically stable, and high-brightness helium, neon, argon, hydrogen, oxygen, and nitrogen GFISs have been generated [4,5]. The Xe-GFIS also exhibits a very narrow beam with a half opening angle of ~0.5°. The ion current stability is good (instability ~2%). The reduced brightness of Xe-GFIS is measured to be 1.3 x 108 Am-2sr-1V-1 at the gas pressure of 10-4 torr, 3 orders of magnitude higher than that of Ga-LMIS and several orders of magnitude higher than that of Xe magnetically enhanced inductively coupled plasma ion source (5.4x103 Am-2sr-1V-1) [6]. In principle, the brightness of the Xe-GFIS can be further enhanced at a higher gas pressure or by using an emitter of a larger radius. The operation temperature can be ~200 K, which is much higher than the cryogenic temperature required for HIM. Thus Xe-GFIS-FIB would be easier to implement than HIM and may become a powerful tool for nanoscale milling and secondary ion mass spectroscopy.
[1] Ward, B.W., J.A. Notte, and N.P. Economou, J. Vac. Sci. & Technol. B 24, 2871 (2006).
[2] T. Y. Fu, L. C. Cheng, C. H. Nien & T. T. Tsong, Phys. Rev. B 64 113401(2001).
[3] H.-S. Kuo, I.-S. Hwang, T.-Y. Fu, J. Y. Wu, C. C. Chang & T. T. Tsong, Nano Lett. 4 2379 (2004)
[4] H.-S. Kuo, I.-S. Hwang, T.-Y. Fu, Y. C. Lin, C. C. Chang & T. T. Tsong, Jap. J. Appl. Phys. 45 8972 (2006).
[5] H.-S. Kuo, I.-S. Hwang, T.-Y. Fu, Y.-H. Lu, C.-Y. Lin, and T. T. Tsong, Appl. Phys. Lett. 92 063106 (2008).
[6] N. S. Smith et al., J. Vac. Technol. B 24, 2902 (2006).