Microstructures for microelectromechanical system (MEMS) applications are widely fabricated using silicon wet bulk micromachining technique. In this method, potassium hydroxide (KOH) is one of the most used anisotropic etchants. It provides high etch rate when it is modified by the addition of hydroxylamine (NH2OH). Moreover, it shows high undercutting which is a desirable property for the fabrication of overhanging microstructures. In this paper, the effect of isopropyl alcohol (IPA) in NH2OH-added KOH on the etching characteristics of Si{100} and Si{110}) is systematically studied. The results are compared with the etching characteristics of IPA-added pure KOH. The undercutting rate reduces drastically when IPA is added to NH2OH + KOH which protects the convex corners of the structures during etching process. At the same time, the etch rate of {110} plane is suppressed considerable which is exploited to expose {110} plane at the mask edges aligned along <100> direction on {100} surface that makes 45° angle with {100} surface and act as a micromirror. © 2023, The Author(s), under exclusive license to Springer Nature Switzerland AG.