Rectangular Scale-Similar Etch Pits in Monocrystalline Diamond
Craig D. McGray, Richard A. Allen, Marc J. Cangemi, Jon C. Geist
Etching of monocrystalline diamond in oxygen and water vapor at 1100° C through small pores in a silicon nitride film produced smooth-walled rectangular cavities. The cavities were imaged by electron microscope and measured by interferometric microscopy. The observed cavities ranged in size from approximately 1 µm up to 72 µm wide, in each case exhibiting smooth, vertical sidewalls, a flat bottom, and a depth equal to half its width. Cavity boundaries were determined to lie along slow-etching (100) crystallographic planes, suggesting the possibility of a powerful class of techniques for high-aspect-ratio bulk micromachining of diamond.