Focused ion beam (FIB) optical-merged lithography has been developed to improve the throughput in delineating the gate pattern of the metal-oxide-semiconductor field-effect transistor. In this process, only the critical part of the pattern is delineated with FIB and merged with optically printed noncritical parts. Ladder silicone spin-on glass (LS-SOG) has been used as the negative resist for the 200 keV Si2+-focused ion beam. The 100 nm polysilicon gate was successfully fabricated using the single-level resist process. The film characteristics of the LS-SOG were also investigated.