MONTE-CARLO SIMULATION OF ANISOTROPIC ETCHING OF SILICON - INVESTIGATION OF [111] SURFACE-PROPERTIES

The etching rate of the (111) surface family is of prime importance fo r microfabrication. However, the experimental values of the correspond ing etch rate are often scattered and the etching mechanism of (111) r emains unclear. In this paper the Monte Carlo simulation results obtai ned from etching of (111) small size substrate are presented. Simulati ons were carried out to simulate the behaviour of the (111) surface in contact with strong base aqueous solutions (R-OH). Simulation shows t hat when etching a small substrate (250 Angstrom x 250 Angstrom), the etch depth against time curve shows a constant part and a linear part. The former is related to the magnitude of Monte Carlo time steps whil e the latter corresponds to the evacuation of one (111) sublayer. Howe ver, the substrate size fails to impact the etching mechanism which re mains unchanged even for an infinite size. The same remark applies to roughness which exhibits a series of alternative peaks.