The optical proximity effect of a next generation super resolution technique

A new super resolution technique with wide applicability and high resolution enhancement has been developed. Various optical properties of the new optics have been analyzed by some optical simulations. Using a spontaneously optimized source shape for the mask pattern itself leads to better applicability with the new optics. From experimental verification, the DOF of the new optics is 1.5 times wider than the modified illumination. An alignment accuracy of 0.1 mu m (on mask) is acceptable between the first and second mask. According to simulation results, the optical proximity effect is reduced by the new optics. These features offer significant merits to photolithography technology. Therefore, we estimate the optical proximity effect by optical image measurements and simulations. From the simulation result, we can use the third source aperture to control the optical proximity effects. For conventional illumination, a 0.35 mu mL/S image is formed by two beam interference. For the new optics, the same pattern is imaged by four beam interference because the UV light is diffracted twice by the mask pattern. While the optical proximity correction system was being developed, it was confirmed that the pattern size fluctuation is sufficiently small for four or more beam interference. The experimental results of an x-z image profile for 0.35 mu m, 0.4 mu m or 0.5 mu m line and any space are consistent with simulation results.