Maskless Wet Etching Silicon in Iodine-Supersaturated KOH Solution

• Published in: IEEE sensors journal Vol. 15; no. 8; pp. 4708 - 4711
• Main Authors: Han, Jianqiang, Yu, Yimao, Li, Sen, Li, Qing
• Format: Journal Article
• Language: English
• Published: IEEE 01-08-2015
• Subjects: Accelerometers; Crystals; Fast-etching crystal plane; Iodine-supersaturated KOH solution; Maskless etching; Microsensors; Sensors; Silicon; Wet etching; microsensors; Maskless etching; fast-etching crystal plane; iodine-supersaturated KOH solution
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2015.2426730

Although maskless wet etching of silicon has been proposed for about two decades, it is not widely used as yet because of rough fast-etching planes etched in KOH-based etchants or lager ratio (r 3 ) between the etching rates of the fast-etching crystal plane and (001) planes etched in TMAH-based etchant. In this paper, the maskless wet etching characteristics of silicon in various etchants are experimental studied. It is found that the fast-etching planes etched in iodine-supersaturated KOH solution are smooth and the intersectant lines of (001) crystal planes and fast-etching planes are straight. The ratio between the etching rates of the fast-etching crystal planes and (001) planes etched in iodine-supersaturated KOH solution is smaller than that of other etchants. The deviation of r 3 in iodine-supersaturated KOH solution is also the smallest among all etchants. In addition, experiments demonstrate that iodine-supersaturated KOH solution has an extremely high stability and durability. All these characteristics prove it satisfies most demands of maskless etching silicon sensors and actuators.