Abstract
This paper reports the highest etch depth of annealed Pyrex glass achieved by wet etching in highly concentrated HF solution, using a low stress chromium–gold with assistance of photoresist as masking layer. The strategies to achieve that are: increasing the etch rate of glass and simultaneously increasing the resistance of Cr/Au mask in the etchant. By annealing the Pyrex glass and using a highly concentrated HF acid, a high etch rate can be obtained. Furthermore, a method to achieve a good resistance of the Cr/Au masking layer in the etching solution is to control the residual stress and to increase the thickness of Au deposition up to 1 μm. In addition, the presence of a hard baked photoresist can improve the etching performance. As a result, a 500-μm thick Pyrex glass wafer was etched through.
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This project is funded by the Institute of Bioengineering and Nanotechnology, Agency for Science, Technology and Research (IBN/04-R44007-OOE).
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Tay, F.E.H., Iliescu, C., Jing, J. et al. Defect-free wet etching through pyrex glass using Cr/Au mask. Microsyst Technol 12, 935–939 (2006). https://doi.org/10.1007/s00542-006-0116-0
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DOI: https://doi.org/10.1007/s00542-006-0116-0