Silicon Y-bifurcated microchannels etched in 25 wt% TMAH water solution

Abstract

In this study, Y-bifurcated microchannels fabricated from a {100} silicon in 25 wt% tetramethylammonium hydroxide water solution at the temperature of 80 °C have been presented and analysed. We studied the etching of acute angles with sides along the <n10> crystallographic directions in the masking layer where 1 < n < 8. We considered symmetrical acute corners in the masking layer with respect to the <100> crystallographic directions. The angles between the appropriate <n10> and <100> crystallographic directions were smaller than 45°. Moreover, we observed asymmetrical acute corners formed by the <n10> and <m10> crystallographic directions, where m ≠ n. We found that the obtained convex corners were not distorted during etching. Consequently, it is not necessary to apply convex corner compensation. These fabricated undistorted convex corners represent the angles of the bifurcations. The sidewalls of the microchannels are defined by etched planes of the {n11} and {100} families. Analytical relations were derived for the widths of the microchannels. The results enable simple and cost-effective fabrication of various complex silicon microfluidic platforms.