Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

High-aspect-ratio bulk micromachining of titanium

Nature Materials volume 3, pages 103–105 (2004)Cite this article

Abstract

Recent process developments have permitted the highly anisotropic bulk micromachining1 of titanium microelectromechanical systems (MEMS). By using the metal anisotropic reactive ion etching with oxidation (MARIO) process, arbitrarily high-aspect-ratio structures with straight sidewalls and micrometre-scale features have been bulk micromachined into titanium substrates of various thicknesses, ranging from 0.5-mm sheet down to 10-μm free-standing titanium foils. Bulk micromachined structures are generally free of residual stresses and are preferred when large, rigid, flat and/or high-force actuators are desired2. However, so far there has been a limited ability to select materials on the basis of specific application in bulk micromachining, primarily because of the predominance of MEMS processes dedicated to single-crystal silicon, such as silicon deep reactive ion etching3. The MARIO process permits the creation of bulk titanium MEMS, which offers potential for the use of a set of material properties beyond those provided by traditional semiconductor-based MEMS. Consequently, the MARIO process enables the fabrication of novel devices that capitalize on these assets to yield enhanced functionalities that would not be possible with traditional micromechanical material systems.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Titanium comb drive actuator.
Figure 2: Microfabricated titanium mirror array.
Figure 3: Deep-etched titanium beam with a notched bottom.
Figure 4: Cross-section of a schematic representation of the MARIO process.

Similar content being viewed by others

References

  1. Pang, S. High-aspect-ratio structures for MEMS. Mater. Res. Soc. Bull. 26, 307–308 (2001).

    Article  CAS  Google Scholar 

  2. Saif, M.T.A. & MacDonald, N.C. Planarity of large MEMS. J. Microelectromech. S. 5, 79–97 (1996).

    Article  CAS  Google Scholar 

  3. Lärmer, F. & Schilp, P. Method of anisotropically etching silicon. German Patent DE4,241,045 (1994).

  4. CRC Handbook of Chemistry and Physics 83rd edn (CRC, Boca Raton, Florida, 2003).

  5. Anstis, G.R., Chantikul, P., Lawn, B.R. & Marshall, D.B. A critical evaluation of indentation techniques for measuring fracture toughness. I. Direct crack measurements. J. Am. Ceram. Soc. 64, 533–538 (1981).

    Article  CAS  Google Scholar 

  6. Donachie, M. Titanium — a Technical Guide 2nd edn (ASM International, Materials Park, Ohio, 2000).

    Google Scholar 

  7. Brunette, D.M. Titanium in Medicine: Material Science, Surface Science, Engineering, Biological Responses, and Medical Applications (Springer, Berlin, 2001).

    Book  Google Scholar 

  8. Hartmann, J., Ensinger, W., Koniger, A., Stritzker, B. & Rauschenbach, B. Formation of titanium nitride coatings by nitrogen plasma immersion ion implantation of evaporated titanium films. J. Vac. Sci. Technol. A 14, 3144–3146 (1996).

    Article  CAS  Google Scholar 

  9. Nunogaki, M. Transformation of titanium surface to TiC- or TiN-ceramics by reactive plasma processing. Mater. Design 22, 601–604 (2001).

    Article  CAS  Google Scholar 

  10. Becker, E.W., Ehrfeld, W., Hagmann, P., Maner, A. & Münchmeyer, D. Fabrication of microstructures with high aspect ratios and great structural heights by synchrotron radiation lithography, galvanoforming, and plastic moulding (LIGA process). Microelectron. Eng. 4, 35–56 (1986).

    Article  CAS  Google Scholar 

  11. Mehregany, M. & Zorman, C. Surface micromachining: a brief introduction. Mater. Res. Soc. Bull. 26, 289–290 (2001).

    Article  CAS  Google Scholar 

  12. O'Mahony, C., Hill, M., Hughes, P.J. & Lane, W.A. Titanium as a micromechanical material. J. Micromech. Microeng. 12, 438–443 (2002).

    Article  CAS  Google Scholar 

  13. Williams, K.R. & Miller, R.S. Etch rates for micromachining processing. J. Microelectromech. S. 5, 256–269 (1996).

    Article  CAS  Google Scholar 

  14. Chauvy, P.-F., Madore, C. & Landolt, D. Electrochemical micromachining of titanium through a patterned oxide film. Electrochem. Solid State 2, 123–125 (1999).

    Article  CAS  Google Scholar 

  15. Pornsin-sirirak, T.N., Tai, Y.C., Nassef, H. & Ho, C.M. Titanium-alloy MEMS wing technology for a micro aerial vehicle application. Sensors Actuators A 89, 95–103 (2001).

    Article  CAS  Google Scholar 

  16. Wada, H., Daesung, L., Krishnamoorthy, S.Z. & Solgaard, O. Process for high speed micro electro mechanical systems (MEMS) scanning mirrors with vertical comb drives. Jpn J. Appl. Phys. 41, 899–901 (2002).

    Article  Google Scholar 

  17. Madou, M. Fundamentals of Microfabrication: the Science of Miniturization 2nd edn (CRC, Boca Raton, Florida, 2002).

    Book  Google Scholar 

  18. Reed, B.W., Chen, J.M., Macdonald, N.C., Silcox, J. & Bertsch, G.F. Fabrication and STEM/EELS measurements of nanometer-scale silicon tips and filaments. Phys. Rev. B 60, 5641–5652 (1999).

    Article  CAS  Google Scholar 

Download references

Acknowledgements

We thank G. D. Cole, E. R. Parker, P. Tavernier, B. Thibeault and the Materials Technology Office at the Defense Advanced Research Projects Agency.

Author information

Authors and Affiliations

  1. Materials Department, University of California, Santa Barbara (UCSB), Santa Barbara, 93106, California, USA

    Marco F. Aimi, Noel C. MacDonald & Abu Samah Zuruzi

  2. Mechanical and Environmental Engineering Department, University of California, Santa Barbara (UCSB), Santa Barbara, 93106, California, USA

    Masa P. Rao, Noel C. MacDonald & David P. Bothman

Authors
  1. Marco F. Aimi
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Masa P. Rao
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Noel C. MacDonald
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Abu Samah Zuruzi
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. David P. Bothman
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Marco F. Aimi.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Aimi, M., Rao, M., MacDonald, N. et al. High-aspect-ratio bulk micromachining of titanium. Nature Mater 3, 103–105 (2004). https://doi.org/10.1038/nmat1058

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nmat1058

This article is cited by

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing