A new organic modifier for anti-stiction

The chemical and mechanical characteristics of a new surface modifier, dialkyldichloromethylsilane (DDMS, CH₃)₂SiCl₂, for stiction-free polysilicon surfaces are reported. The main strategy is to replace the conventional monoalkyl-trichlorosilane (MTS, RSiCl₃) such as octadecyltrichlorosilane (ODTS) or 1H,1H,2H,2H-perfluorodecyltrichlorosilane (FDTS) with dichlorodisilane (DDS, R₂SiCl₂) with two short chains, especially DDMS. DDMS, with shorter chains in aprotic media, rapidly deposits on the chemically oxidized polysilicon surface at room temperature and successfully prevents long cantilevers 3 mm in length from in-use as well as release stiction. DDMS-modified polysilicon surfaces exhibit satisfactory hydrophobicity, long term stability and thermal stability, which are comparable to those of FDTS. DDMS as an alternative to FDTS and ODTS provides a few valuable advantages; ease in handling and storage of the solution, low temperature-dependence and low cost. In addition to the new modifier molecule, the simplified process of direct release right after washing the modified surface with isooctane was proposed to cut the processing time