Variable UV laser exposure processing of photosensitive glass-ceramics: maskless micro- to meso-scale structure fabrication
- 239 Downloads
A novel variable UV laser processing technique was developed that enables the concurrent fabrication of structures in photosensitive glass-ceramic (PSGC) materials that range from the micro-scale to the meso-scale domains. This technique combines the advantages of direct-write volumetric laser patterning and batch chemical processing. The merged non-thermal laser fabrication approach relies on the ability to precisely and selectively alter the chemical etch rate of the PSGC by varying the laser exposure during pattern formation. The present study determined that the chemical etch rate of a commercial photosensitive glass-ceramic (FoturanTM, Schott Corp., Germany) in dilute hydrofluoric (HF) acid is strongly dependent on the incident laser irradiance during patterning at λ=266 nm and λ=355 nm. For low laser irradiances, the etch rate ratio (Rexposed/Runexposed) increased nearly linearly with laser irradiance. The slopes of the linear ranges of the etch rate ratios were measured to be 435.9±46.7 μm2/mW and 46.2±2.3 μm2/mW for λ=266 nm and λ=355 nm, respectively. For high laser irradiances, the measured etch rate ratio saturated at ∼30:1 with a maximum absolute etch rate of 18.62±0.30 μm/min. The maximum absolute chemical etch rate was independent of the exposure wavelength. Consequently, variation of the laser exposure during direct-write patterning permits the formation of variegated and proximal high and low aspect ratio structures on a common substrate. The results show that adjacent microstructures with aspect ratios ranging from <1:1 to ∼30:1 can be fabricated in a single, simultaneous batch chemical etch step without the need for a complex masking sequence or post-process ablation step. This new technique facilitates rapid prototype processing with pattern and component uniformity, and achieves material processing over large areas without incurring high cost.
Unable to display preview. Download preview PDF.
- 1.Brannon J, Greer J, Helvajian H (1999) Laser Processing for Microengineering Applications. In: Helvajian H (ed) Microengineering Aerospace Systems. The Aerospace Press, El SegundoGoogle Scholar
- 5.Holand W, Beall GH (2002) Glass-Ceramic Technology. The American Ceramic Society, Westerville, OHGoogle Scholar
- 7.Tashiro T, Wada M (1963) Glass-Ceramics Crystallized with Zirconia. In: Advances in Glass Technology. Plenum, New YorkGoogle Scholar
- 8.Pincus AG (1971) Application of Glass-Ceramics. In: Hench LL, Frieman SW (eds) Advances in Nucleation and Crystallization in Glasses. The American Ceramic Society, Columbus, OHGoogle Scholar
- 11.Grossman DG (1982) Glass-Ceramic Application. In: Simmons JH, Uhlmann DR, Beall GH (eds) Nucleation and Crystallization in Glasses. The American Ceramic Society, Columbus, OHGoogle Scholar
- 19.Berezhnoi A (1970) Glass-Ceramics and Photo-Sitalls. Plenum, New YorkGoogle Scholar
- 21.Fuqua PD, Taylor DP, Helvajian H, Hansen WW, Abraham MH (2000) Mat Res Soc Symp Proc 624:79Google Scholar
- 22.Janson SW, Huang A, Hansen WW, Helvajian H (2004) AIAA paper 2004–6701, Conference on Micro-Nano-Technologies, Monterey, CA, USAGoogle Scholar
- 27.Livingston FE, Helvajian H (2004) US Patent No 6,783,920, issued Aug 31Google Scholar
- 28.Livingston FE, Adams PM, Helvajian H (2005) submitted to J Appl PhysGoogle Scholar
- 31.Livingston FE, Helvajian H (2005) Photophysical Processes that Lead to Ablation-Free Microfabrication in Glass-Ceramic Materials. In: 3D Laser Microfabrication. Misawa H, Juodkazis S (eds) Wiley-VCH Verlag GmbH & Co Weinheim, Germany, in pressGoogle Scholar