One of the main goals of micromechanical systems (MEMS) fabrication is microdevice integration with standard integrated circuit (IC) technologies, such as bipolar or the more prevalent complementary metal oxide semiconductor (CMOS) processes. To that end, it has been found that the anisotropic silicon etchant tetra-methyl ammonium-hydroxide (TMAH) can be effectively used in a post-processing step with CMOS-based fabrication by doping it with silicic acid to prevent the unwanted etching of exposed alluminum. Furthermore, the addition of ammonium persulfate to the TMAH/silicic acid solution enhances etch rate and surface quality. The final etching solution, called dual-doped TMAH, is a CMOS-compatible, highly selective to silicon over aluminum, and can therefore allow an aluminum layer to be used as an etch mask. In this paper, we utilize dual-doped TMAH towards the fabrication of a microstructure made entirely of aluminum. A flexing beam microactuar suspended over a bulk micromachined silicon cavity is presented for use as a magnetometer
Application of Dual Doped TMAH Silicon Etchant in the Fabrication of a Micromachined Aluminium Flexing Beam Actuator
Ferrario, Lorenza;
2002-01-01
Abstract
One of the main goals of micromechanical systems (MEMS) fabrication is microdevice integration with standard integrated circuit (IC) technologies, such as bipolar or the more prevalent complementary metal oxide semiconductor (CMOS) processes. To that end, it has been found that the anisotropic silicon etchant tetra-methyl ammonium-hydroxide (TMAH) can be effectively used in a post-processing step with CMOS-based fabrication by doping it with silicic acid to prevent the unwanted etching of exposed alluminum. Furthermore, the addition of ammonium persulfate to the TMAH/silicic acid solution enhances etch rate and surface quality. The final etching solution, called dual-doped TMAH, is a CMOS-compatible, highly selective to silicon over aluminum, and can therefore allow an aluminum layer to be used as an etch mask. In this paper, we utilize dual-doped TMAH towards the fabrication of a microstructure made entirely of aluminum. A flexing beam microactuar suspended over a bulk micromachined silicon cavity is presented for use as a magnetometerI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
