Study on In Situ Etching Rate Monitoring in Numerically Controlled Local Wet Etching


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Numerically controlled local wet etching (NC-LWE) is very promising technique for deterministic figuring of ultraprecision optical devices, such as aspherical lens, photo mask substrate and X-ray or neutron focusing mirror. NC-LWE technique is non-contact removal process using chemical reaction between etchant and surface of workpiece, so this technique enables us to figure the objective shape without introduction both substrate deformation and sub-surface damage. It is essential to measure temperature and concentration of the etchant to maintain the material removal rate constant over a processing time, since the etching rate of NC-LWE strongly depends on these parameters. Hydrofluoric (HF) acid solution is used as an etchant for synthesized quartz glass. We aim to develop an in situ monitoring system of etchant concentration using Raman spectroscopy and electric conductivity measurement. Raman spectroscopy measurement result indicates that there is a good linear relationship between HF concentration and intensity ratio of two specific Raman bands.



Key Engineering Materials (Volumes 523-524)

Edited by:

Tojiro Aoyama, Hideki Aoyama, Atsushi Matsubara, Hayato Yoshioka and Libo Zhou




N. Shimozono et al., "Study on In Situ Etching Rate Monitoring in Numerically Controlled Local Wet Etching", Key Engineering Materials, Vols. 523-524, pp. 34-39, 2012

Online since:

November 2012




[1] Y. Namba, T. Shimomura, A. Fushiki, A. Beaucamp, I. Inasaki, H. Kunieda, Y. Ogasaka, K. Yamashita, Ultra-precision polishing of electroless nickel molding dies for shorter wavelength applications, Annals of the CIRP 57 (2008) 337-340.


[2] Y. Namba, H. Kobayashi, H. Suzuki, K. Yamashita, Ultraprecision surface grinding of chemical vapor deposited silicon carbide for X-ray mirrors using resinoid-bonded diamond wheels, Annals of the CIRP 48 (1999) 277-280.


[3] A. Takeuchi, Y. Suzuki, H. Takano, Y. Terada, Kirkpatrick-Baez type X-ray focusing mirror fabricated by the bent-polishing method, Rev. Sci. Instrum. 76 (2005) 093708_1-4.


[4] K. Yamamura, K. Yamauchi, H. Mimura, Y. Sano, A. Saito, K. Endo, A. Souvorov, M. Yabashi, M., K. Tamasaku, T. Ishikawa, Y. Mori, Fabrication of elliptical mirror at nanometer-level accuracy for hard X-ray focusing by numerically controlled plasma chemical vaporization machining, Rev. Sci. Instrum. 74 (2003).


[5] L. De Chiffre, H. Kunzmann, G. -N. Peggs, D. -A. Lucca, Surfaces in Precision Engineering, Microengineering and Nanotechnology, Annals of the CIRP 52 (2003) 561-577.


[6] K. Yamamura, Y. Sano, M. Shibahara, K. Yamauchi, H. Mimura, K. Endo, Y. Mori, Ultraprecision Machining Utilizing Numerically Controlled Scanning of Localized Atmospheric Pressure Plasma, Jpn. J. Appl. Phys. 45 (2006) 8270-8276.


[7] K. Yamamura, Fabrication of Ultra Precision Optics by Numerically Controlled Local Wet Etching, Annals of the CIRP 56 (2007) 541-544.


[8] K. Yamamura, H. Takai, Figuring of ultraprecision aspherical focusing mirror using numerically controlled local wet etching, Proc. 10th Anniversary International Conference of the European Society for Precision Engineering and Nanotechnology (2008).


[9] K. Yamamura, M. Nagano, H. Takai, N. Zettsu, D. Yamazaki, R. Maruyama, K. Soyama, S. Shimada, Figuring of plano-elliptical neutron focusing mirror by local wet etching, Opt. Express 17 (2009) 6414-6420.


[10] M. Nagano, F. Yamaga, N. Zettsu, D. Yamazaki, R. Maruyama, K. Soyama, K. Yamamura, Development of fabrication process for aspherical neutron focusing mirror using numerically controlled local wet etching with low-pressure polishing, Nucl. Instr. and Meth., A 634 (2011).


[11] O.F. Nielsen, The Structure of liquid water. A low frequency (10-400 cm-1) Raman study, Chem. Phys. Lett. 60 (1979) 515-517.

[12] G. Kang, K. Lee, H. Park, J. Lee, Y. Jung, K. Kim, B. Son, H. Park, Quantitative analysis of mixed hydrofluoric and nitric acids using Raman spectroscopy with partial least squares regression, Talanta 81 (2010) 1413-1417.