ArFi lithogrphy optimization for thin OMOG reticle with fast aerial imaging

As half pitch shrinks to sub 20nm dimensions, the latest hybrid IC (integrated circuit) designs include a greater number of features that approach the resolution limits of the scanner than in the previous generation of IC designs. This trend includes stringent design rules and complex, ever smaller optical proximity correction (OPC) structures. In this regime, a new type of mask, known as opaque MoSi on glass (OMOG), has been introduced to overcome the shortcomings of the well-established phase shift masks (PSM). As for lithography, scanner and mask determine ultimate intra-field performance as one approaches scanner resolution limits. Holistic lithography techniques have been developed to optimize the interrelated mask and scanner effects on critical dimension uniformity (CDU) and common process window (PW) for the most demanding sub 20nm node features. This paper presents an efficient and production worthy methodology for evaluating the CDU, PW, and 3D effect fingerprints of the latest immersion scanner and thin OMOG masks, and minimizing them using high-order optimizers of the latest holistic ArFi lithography.