Selective removal of micro-corrugation by anisotropic wet etching

We conducted an investigation to find a corrugation removal mechanism selectively by anisotropic wet etching to reduce a periodic corrugation, called "scalloping", formed on the sidewalls of microstructures by Deep Reactive Ion Etching (D-RIE). We analyzed the corrugation removal mechanism by using an etching distribution pattern, and then conducted several equations to predict the corrugation removal time by the etching. We experimentally tried to perform a selective removal of the corrugation by using 50% KOH (40 deg-C). The corrugation formed on Si{100} sidewall surfaces gradually reduced in size with the advance of the etching, and it was completely removed after 5.0 min of etching. The necessary etching time and shape change of the corrugation removal were coincident with the results conducted by the distribution pattern of the etching.