A novel RET for random pattern formation utilizing attenuating non-phase-shift assist pattern

A novel resolution enhancement technology (RET) for random pattern formation which utilizes attenuating non-phase-shift (Atten-NPS) assist pattern is proposed based on optical image calculation. By addition of Atten-NPS assist pattern on mask for isolated Feature, much improvement of imaging characteristics is-obtained under modified illumination. In the application of this RET, Cr aperture size of assist pattern on mask can make similar to that of main pattern. Consequently, difficulty in mask fabrication for conventional assist pattern method will be overcome.