Fabrication of large-scale uniform submicron inverted pyramid pit arrays on silicon substrates by laser interference lithography

We propose a new method for fabricating large-scale uniform high-quality submicron inverted pyramid pit arrays by laser interference lithography (LIL), combined with dry etching and wet etching. In this process, uniform photoresist dot arrays are fabricated by LIL for 2-inch wafer. Dry etching is used to ensure the formation of the fluorocarbon organic polymer (FOP) mask layer. Wet etching parameters are investigated in details and inverted pyramid pits with {111} sidewalls are formed by anisotropic wet etching. Using this method, we have successfully produced uniform high-quality inverted pyramid pit arrays with the average size of 240 nm and the period of 450 nm. The size of pits can be tailored between 200 nm and 400 nm and the size deviation of inverted pyramid pits is 6.7% over the whole 2-inch wafer. This method offers a simple, less time consuming and cost-effective process of micro-nano pattern fabrication. Besides, GeSi QDs are quantitatively investigated by a nucleation model which shows GeSi QDs are preferentially grown at the tip of inverted pyramid pit and four intersection lines of two {111} planes inside the pit.