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Over the last 5 years, Japanese consortium, Semiconductor Leading Edge Technologies Inc. (Selete), lead the way in developing unified mask data format. Specification of the format was released as OASIS.VSB and registered to SEMI standard, P44. It is expected that using OASIS.VSB would reduce TAT and improve efficient usage of data infrastructure. OASIS.VSB has advantages for mask data preparation since OASIS.VSB is based on OASIS (TM) (SEMI P39) and OASIS compliant software is already commercially available.

Although fundamental evaluation of OASIS.VSB have been made by Selete on technical feasibility with VSB mask writers, its performance and advantage of data handling improvement is still controversial. We have been evaluating OASIS.VSB in order to estimate the impact of data handling improvement at mask manufacturer. Figure 1 shows that OASIS.VSB has good compression ratio compared to certain VSB mask data format. Although compression ratio partly depends on data and conversion software, OASIS.VSB is about 0.7 times as small as VSB data format on weighted basis average. Furthermore, we have confirmed by simulation that OASIS.VSB can hardly affect shot count and writing time.

Unification of mask data format by OASIS.VSB can realize flexible mask data preparation (MDP) and reduce a cost of data storage. To achieve further TAT reduction, it is necessary to apply OASIS.VSB to not only mask writing data but other mask making processes such as die to database inspection and mask rule check (MRC).