Deep plasma silicon etch for microfluidic applications

Various microfluidic devices like micro pumps, micro dispensers, micro pipe ttes, etc, are produced by the GeSiM mbH Grosserkmannsdolf. Fabrication of such microsystems includes the realization of three-dimensional silicon sub strates. Plasma-based silicon etch processes are key technologies for exact patterning the substrates from both surfaces. Typically, etch depths of 10 to 500 mu m, aspect ratios >25 and the applica tion of conventional mask systems are required. Etch rates between 2 and 6 mu m/min, a uniformity (3 sigma) below 5%, an excellent anisotropy and a se lectivity of >50:1 for photoresists and >150:1 for SiO2 can be realized usi ng an etch system produced by Surface Technology Systems Limited (STS), UK and the ASE(TM) process based on fluorine etch chemistry. This technique ov ercomes the disadvantages of conventional wet silicon etch processes, like the influence of crystal orientation on etch rate. Our intention was to investigate the influence of gas flow rates, process g as pressure, supplied power and time sequence on etch rate and edge profile . The results should be used to vary process parameters according to the re quirements of application. (C) 1999 Elsevier Science S.A. All rights reserv ed.