Pushing the limits of RET with different illumination optimization methods

As we proceed to 22 nm technology node without any advancement from the front of numerical aperture or EUV, it has become really challenging to come up with a robust solution to confront resolution and process window. At this stage along with litho friendly design and new advent in lithographic processes, it has become vital to acquire highly optimized resolution enhancement technology (RET). In this paper, we review different realm of illumination optimization techniques with combination of currently available source shapes along with pixilated source optimization. Different source shapes are tested over various technology designs such as 32 nm and 22 nm designs for better fidelity and process window. We optimize different source shapes manually and also evaluate fidelity with optimized pixilated source. The results demonstrate how we can achieve better resolution for some layout patterns with different illumination optimization methods.