We design a C-shaped aperture which overcomes the diffraction limit of light to produce a high-brightness nano-size light spot. For optical nano lithography, we construct a nano patterning system using an optical probe which adopts a solid immersion lens (SIL), the 120 nm thickness aluminum film on the bottom surface of the SIL and the C-shaped aperture engraved in the metal film. Light source is a diode laser of 405nm wavelength to expose h-line photoresist(PR). A linear stage holding the optical probe makes the nano aperture contact with the PR coated on silicon wafer. Using this patterning system, we obtain sub 100nm array patterns and measure the system performance in various exposure conditions to verify the feasibility of plasmonic lithography.