Figure 1 schematically illustrates the servo pattern integration scheme of our proposed imprint guided two-step DSA process. A thin imprint resist layer containing two pattern regions is created using imprint lithography and then the imprinted resist pattern will be used as a copolymer guiding prepattern for DSA. The data zone has a 2-D hole-tone dot-array pattern at a low density of , whereas the servo zone has many 1-D grooves in the shape of servo patterns. With this method, optical lithography is used to define these two separate zones: data zone and servo zone, so the two DSA processes and subsequent pattern transfer process can be separately optimized in order to achieve the best DSA and pattern transfer results for each zone. For example, while processing the data zone, the servo zone is protected by an optical resist. The imprint resist thickness in the data zone can be trimmed down even more to 2 to 3 nm in order to minimize topographical effects for the best pattern transfer results in the data zone. However, in the servo zone, a certain groove height in the resist prepattern, ranging from 20 to 30 nm, is necessary in order to guide the DSA of the BCP along the groove sidewall. Since the sphere-forming BCP film with a monolayer thickness was used for the data zone and servo zone, the concentration of the BCP solution needs be separately optimized. It should be noted here that two DSA steps are not always necessary in our proposed approach. It can be done in one-single DSA step if the cylinder-forming BCP film, such as BCP film, is used in both the data area and the servo area, as previously reported.24 However, it has been proven that has a higher Flory–Huggins interaction parameter value of 0.26 than that of other BCP materials, such as of 0.06. With the commercially available cylinder-forming BCP material, the highest BCP density with the lowest molecular weight is about . The high value BCP material allows us to conduct the process development for higher densities up to 4 to .14,16 Once the first DSA process in the data zone is completed, the BCP patterns are subsequently transferred into the underlying quartz substrate through a Cr hard mask layer to form pillar-tone quartz dots in the data zone. A similar processing flow can be applied to the servo zone. Unlike the data zone, the servo zone uses a 1-D groove prepattern as guiding patterns for the second DSA process. Finally, a servo-integrated BPM template is fabricated after two DSA steps based on this integration scheme.