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Maskless Single-Sided Wet Etching Process for the Fabrication of Ultra-Low Distortion Polyimide Membranes

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Abstract

A process for volume production of ultra-low distortion (<200 ppm), thin polyimide membranes on silicon wafers was developed using the RotoEtch™ dynamic fluid confinement tool. A critical advantage of the process is that it exposes the sample to the etching solution over a selected area on one side only, without contacting, wetting, or otherwise contaminating the front surface. This unique feature allows the etching away of a circular portion (over 40 mm diameter) of the backside of a patterned silicon wafer to form a freestanding thin polyimide membrane (<1 μim thick). The polyimide film is patterned prior to wet etching with a sub-micron period grating (200 nm period). The resulting distortion of the grating on the freestanding membrane is less than 200 ppm over the entire membrane area. This process seems ideally suited for instances—like the one above—when immersion, contacting, or contamination of one side of the sample would be impossible or impractical. It also allows backetching finished micro-structures that would otherwise be disturbed or destroyed by immersion in the fluid. Finally, it speeds up the fabrication of freestanding films since it does not require masking or any other form of front-side protection or backside lithographic steps. In this paper we report on a silicon through-etch process based on an HF:HNO3 acid mixture which typically forms membranes in only 10-20 minutes. Since polyimide easily distorts due to excessive heat or mechanical strain, the etching process needs to be carefully controlled. This process is also ideal for forming large membranes of other HF:HNO3-inert materials such as silicon carbide or diamond.

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References

  1. T.H. Markert, J.M. Bauer, C.R. Canizares, T. Isobe, S. Nenonen, J. O’Connor, M.L. Schattenburg, K. Flanagan, and M.V. Zombeck, in EUV, X-ray, and Gamma-Ray Instrumentation for Astronomy II (Proc. SPIE 1549), eds. O.H.W. Siegmund and R.E. Rothschild (SPIE, Bellingham, WA), 408–419 (1991).

  2. R.J. Aucoin, T.H. Markert, S. Nenonen, K. Flanagan, and M. Barbera, in EUV, X-ray, and Gamma-Ray Instrumentation for Astronomy V (Proc. SPIE 2280), eds. O.H.W. Siegmund and J.V. Vallerga (SPIE, Bellingham, WA), 134–144 (1994).

  3. R. Mutikainen, V.-P. Viitanen, and S. Nenonen, J. X-ray Sci. Technol. 4, 82 (1994).

    Article  CAS  Google Scholar 

  4. M.L. Schattenburg, E.H. Anderson, and H.I. Smith, Physica Scripta 41, 13–20 (1990).

    Article  CAS  Google Scholar 

  5. M.L. Schattenburg, R.J. Aucoin, R.C. Fleming, I. Plotnik, J. Porter, and H.I. Smith, in EUV, X-ray, and Gamma-Ray Instrumentation for Astronomy V (Proc. SPIE 2280), eds. O.H.W. Siegmund and J. Vallerga (SPIE, Bellingham, WA), 181–190 (1994).

  6. B.M. Gong and Y.D. Ye, J. Vac. Sci. Technol. 19, 1204–1207 (1981).

    Article  CAS  Google Scholar 

  7. T. Wada, S. Sakurai, and K. Kawabuchi, J. Vac. Sci. Technol. 19, 1208–1210 (1981).

    Article  CAS  Google Scholar 

  8. J.B. Huang and B.M. Gong, J. Vac. Sci. Technol. B 3, 253–257 (1985).

    Article  CAS  Google Scholar 

  9. K. Early, M. L. Schattenburg, and H. I. Smith, Microelectronic Engineering 11, 317–321 (1990).

    Article  CAS  Google Scholar 

  10. A. Yen, R. A. Ghanbari, Y.-C. Ku, W. Chu, M. L. Schattenburg, J. M. Carter, and H. I. Smith, Microelectronic Engineering 13, 271–274 (1991).

    Article  CAS  Google Scholar 

  11. D.C. Flanders, Ph.D. Thesis, Massachusetts Institute of Technology, 1978.

    Google Scholar 

  12. A.M. Hawryluk, Ph.D. Thesis, Massachusetts Institute of Technology, 1981.

    Google Scholar 

  13. G. Kaminski, J. Vac. Sci. Technol. B 4, 1015–1024 (1985).

    Article  Google Scholar 

  14. H. Linde and L. Austin, J. Electrochem. Soc. 139, 1170–1174 (1992).

    Article  CAS  Google Scholar 

  15. J.L. Vossen and W. Kem, Thin Film Processes (Academic Press, Orlando, FL, 1978), Chapter V-l.

    Google Scholar 

  16. SEZ America, Inc., 4824 South 40th St., Phoenix, AZ 85040.

  17. R. Fuentes, J. Vac. Sci. Technol. B 10, 3159–3163 (1992).

    Article  CAS  Google Scholar 

  18. S.D. Whitehair, J.E. Yehoda, R. Fuentes, R.A. Roy, C.R. Guarnieri, and J.J. Cuomo, in Materials Aspects of X-ray Lithography (MRS Symposium Proceedings 306), ed. G.K. Celler and J.R. Maldonado, 97–102 (1993).

  19. T.H. Markert, C.R. Canizares, D. Dewey, M. McGuirk, C. Pak, and M.L. Schattenburg, in EUV,X-ray, and Gamma-Ray Instrumentation for Astronomy V (Proc. SPIE 2280), eds. O. H. W Siegmund and J. Vallerga (SPIE, Bellingham, WA), 168–180 (1994).

  20. D. Dewey, D.N. Humphries, G.Y. McLean, and D.A. Moschella, in EUV, X-ray, and Gamma-Ray Instrumentation for Astronomy V (Proc. SPIE 2280), eds. O. H. W. Siegmund and J. Vallerga (SPIE, Bellingham, WA), 257–271 (1994).

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Schattenburg, M.L., Fuentes, R.I., Czernienko, G. et al. Maskless Single-Sided Wet Etching Process for the Fabrication of Ultra-Low Distortion Polyimide Membranes. MRS Online Proceedings Library 356, 615–620 (1994). https://doi.org/10.1557/PROC-356-615

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  • DOI: https://doi.org/10.1557/PROC-356-615

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