Multi-patterning techniques with ArF immersion lithography continue to be extended into the 10 and 7 nm nodes. With increasingly challenging process control requirements (CD, overlay, edge placement error), the lithography and patterning tools need to find ways to minimize variation and maintain process margin to achieve high yields. This paper will describe new advances in light source technologies that can regain imaging margins by optimizing light source bandwidth settings in concert with OPC retargeting to take advantage of the contrast improvements1,2 afforded by lower bandwidth. In addition to simulation studies reported previously3,4, on-wafer measurements were collected showing the progressive improvements gained with lowering bandwidth on an existing mask as well as reoptimizing a mask to leverage this lower bandwidth setting. To fully leverage this capability, further improvements in bandwidth stability are going to be featured on a new ArF light source along with an integrated solution that allows the bandwidth target to be commanded by scanner recipe. This will allow lithographers to optimize layers that need further improvements in patterning by using lower bandwidth while continuing to run existing layers with standard, 300 fm bandwidth targets. With the introduction of a new DUV light source, this paper will also describe improvements that continue to reduce running costs in an effort to counteract the escalating costs of multi-patterning lithography.