New class of surface modifiers for stiction reduction

Abstract

In order to achieve stiction-free polysilicon surfaces, we have suggested a new class of chemical grafting precursors and confirmed their excellent characteristics. The strategy is to adopt dialkyldichlorosilanes (DDS, R2SiCl2) instead of monoalkyltrichlorosilanes (MTS, RSiCl3) such as octadecyltrichlorosilane (OTS, C18H37SiCl3) or 1H,1H,2H,-2H-perfluorodecyltrichlorosilane (FDTS, C10H4F17SiCl3). DDS has two short chains and compactly deposits on the hydrophilic polysilicon surface. DDS coated surface is even superior to those of conventional compounds in some respects. Since interactions among precursor molecules are reduced, conglomeration both in homogeneous solution and on surface can be effectively avoided. No difference was found between results from the processes in ambient environment and in dry box. And the final quality of the modified surfaces is much less dependent on temperature. In addition, DDS has some advantages of remarkably reduced process time and acceptably low cost. Even the cantilevers with 3 mm in length can be protected successfully from the stiction.