See also O. Tabata, R. Asahi, H. Funabashi, K. Shimaoka, and S. Sugiyama, Anisotropic etching of silicon in TMAH solutions, Sensors and Actuators, A34, 51-57, 1992
Table from V. Temesvary, S. Wu, W. Hsieh, Y-C Tai, and D. Miu, Design, Fabrication and Testing of Silicon Microgimbals for Super-Compact Ridid Disk Drives, J. Microelectromechanical systems 4, 22.
(TMAH is 15% wt) TMAH TMAH EDP Temperature 80C 90C 95C Etch rate (100) Si (&um/hr) 40 65 90 Si:LPCVD LTO oxide 1190:1 800:1 - Si:2E20/cc B doped Si 27:1 20:1 >500:1 Si:1E21/cc B doped Si 100:1 92:1 >500:1
Author SCHNAKENBERG, U.; Benecke, W.; Lochel, B.; Ullerich, S.; Lange, P.; Fraunhofer-Inst. fur Mikrostrukturtech., Berlin, Germany Title NH/sub 4/OH-based etchants for silicon micromachining: influence of additives and stability of passivation layers Source Eurosensors IV '90; Part: Karlsruhe, West Germany; Part: 1-3 Oct. 1990; Sponsored by: EPS; EUREL; IEEE; et al; Sensors and Actuators A (Physical); vol.A25, no.1-3; Oct. 1990-Jan. 1991 pp.; pp. 1-7 pp. Abstract Solutions based on ammonium hydroxide and water were investigated for anisotropic etching of monocrystalline silicon. In 2.65 M NH/sub 3/ solutions at 80 degrees C, the addition of H/sub 2/O/sub 2/ in a concentration between 0. 65*10/sup -2/ M and 1.84*10/sup -2/ M increases the silicon etch rate in the (100) direction to 75 mu m/h, which is a factor of about 2.5 higher compared to pure etchants. In addition, when the pH value was adjusted above 11.3, silicon etching proceeds in H/sub 2/O/sub 2/-doped solutions without formation of pyramidal-shaped hillocks. The influence of the pH value and H/sub 2/O/sub 2/ concentration on the etching behaviour is discussed in detail. Passivation layers, like silicon oxides and silicon nitrides formed under various preparation conditions, and metals show excellent stability in AHW solutions. The temperature dependence of etch rates as well as the influence of post-treatments on the etching behaviour is discussed Author SCHNAKENBERG, U.; Benecke, W.; Lochel, B.; Fraunhofer-Inst. fur Mikrostrukturtech., Berlin, West Germany Title NH/sub 4/OH-based etchants for silicon micromachining Source 5th International Conference on Solid-State Sensors and Actuators and Eurosensors III; Part: Montreux, Switzerland; Pa rt: 25-30 June 1989; Sponsored by: Swiss Soc. Sensor Technol.; IEEE; Sensors and Actuators A (Physical); vol.A23, no.1-3; April 1990 pp.; pp. 1031-5 pp. Abstract Wet chemical etchants based on ammonium hydroxide-water (AHW) solutions for micromachining monocrystalline silicon are described. The etchants can be applied under clean-room conditions within standard IC fabrication lines. The nature of AHW solutions is discussed with respect to anisotropy and selectivity. At 75 degrees C and 9 wt.% AHW, a maximum etch Si/sub 3/N/sub 4/ and highly boron-doped silicon. Aluminium will not be attacked by silicon-doped AHW etchants. Therefore, standard IC metallization techniques can be used for device fabrication. The application of AHW solutions to the fabrication of basic micromechanical structures is demonstrated