Approach to analyze decomposition impact for photomask fabrication

Double patterning technology (DPT) is one of candidates to achieve 45nm or 32nm half-pitch and is getting popular as ITRS2006update(1). ITRS2006update specifies the tight specification of image-placement and the difference of CD mean-to target of two masks, and they are also evaluated and reported(2). From photomask fabrication viewpoint or just even employing actual wafer exposure experiment, it's much difficult to evaluate actual impact on wafer using DPT. Because what observed on wafer is mixture of not only photomask-property but also exposure's one and new topic of hard-mask process'. In this paper, one evaluation procedure will be proposed using actual two photomasks and the DPT impact on wafer just from two photomasks will be demonstrated. Then the approach of wafer image composing procedure with photomask-SEM image, photomask measurement and exposure simulation will be discussed