Fabrication of Freeform Micro Optics by Focused Ion Beam

Abstract:

In this work, two kinds of freeform micro optics were successfully fabricated by using focused ion beam machining. A divergence compensation method was applied to optimize the machining process. Both dynamic variation of the sputter yield and the extra ion flux contributed by the beam tail were taken into consideration. Measurement results on the surface topography indicated that 3-fold improvement of the relative divergence was achieved for both optics when compared with conventional focused ion beam milling without any corrections. Furthermore, investigations on the influences of scanning strategies, including raster scan, serpentine scan and contour scan, were carried out. The serpentine scan is recommended for the fabrication of freeform optics by focused ion beam technology owing to the minimal beam travelling distance over the pattern area.

• Periodical: Key Engineering Materials (Volume 516)
• Pages: 414-419
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.516.414
• Online since: June 2012
• Authors: Ji Ning Sun, Xi Chun Luo, Wen Long Chang, James M. Ritchie
• Keywords: Divergence Compensation, Focused Ion Beam (FIB), Freeform Structure, Micro Optics, Scanning Strategy

References

[1] K. Reimer, H.J. Quenzer, M. Jürss, B. Wagner, Micro-optic fabrication using one-level gray-tone lithography, SPIE International Society for Optical (1997) 279-288.

DOI: 10.1117/12.271425

[2] M. Rossi, I. Kallioniemi, Micro-optical modules fabricated by high-precision replication processes, Diffractive Optics and Micro-Optics, R. Magnusson, ed., Vol. 75 of OSA Trends in Optics and Photonics Series (Optical Society of America, 2002), paper DTuC1.

DOI: 10.1364/domo.2002.dtuc1

[3] M. Davies, C. Evans, S. Patterson, R. Vohra, B. Bergner, Application of precision diamond machining to the manufacture of micro-photonics components, Proceedings of SPIE 5183 (2003) 94-108.

DOI: 10.1117/12.506373

[4] D.T. Moore, Gradient-index optics: a review, Appl. Opt. 19 (1980) 1035-1038.

[5] L. Harriott, Beam size measurements in focused ion beam systems, J. Vac. Sci. Technol., A: Vacuum, Surfaces, and Films 8 (1990) 899-901.

DOI: 10.1116/1.576893

[6] M.J. Vasile, J. Xie, R. Nassar, Depth control of focused ion-beam milling from a numerical model of the sputter process, J. Vac. Sci. Technol., B: Microelectronics and Nanometer Structures. 17 (1999) 3085-3091.

DOI: 10.1116/1.590959

[7] J. Sun, X. Luo, J. Ritchie, T. Hrncir, A predictive divergence compensation approach for the fabrication of three dimensional microstructures using focused ion beam machining, P I Mech. Eng. B J Eng. (accepted manuscript).

DOI: 10.1177/0954405411408185

[8] W. Möller, W. Eckstein, Tridyn-A TRIM simulation code including dynamic composition changes, Nucl. Instrum. Methods Phys. Res., Sect. B 2 (1984) 814-818.

DOI: 10.1016/0168-583x(84)90321-5

[9] L. Frey, C. Lehrer and H. Ryssel, Nanoscale effects in focused ion beam processing, Appl. Phys. A: Materials Science & Processing 76 (2003) 1017-1023.

DOI: 10.1007/s00339-002-1943-1

[10] D. Adams, M. Vasile, Accurate focused ion beam sculpting of silicon using a variable pixel dwell time approach, J. Vac. Sci. Technol., B: Microelectronics and Nanometer Structures 24 (2006) 836-844.

DOI: 10.1116/1.2184325