Mask data preparation has become a major concern in the supply chain from design to the fab. The mask industry is facing a number of problems induced by a massive introduction of OPC. Affecting the design flow the exponentially escalating data volume came into focus because the data-prep infrastructure fails to keep up with this development. As a consequence the turn around time from tape out to "ready to write" data is permanently rising from a couple of hours 2 years ago to many days/weeks nowadays. Computation times of many days on modern workstations is no exception anymore. Especially when mask data have to be converted to another writing tool data format or just a mask manufacturing process has to be adapted by modifying the data bias, we encountered computing times of more than hundred hours for a single layer. We found a way to reduce these computation times by a factor of more than 100 by introducing distributed computing on a Linux based cluster.
%675$&7By approaching the physical resolution limits of optical lithography for a given wavelength, data complexity on certain layers of chip layouts increases, while feature sizes decrease. This becomes even more apparent when introducing optical enhancement techniques. At the same time, more and more complex procedures to fracture mask data out of a DRC clean chip-GDS2 require checks on mask data regarding integrity, as well as mask manufacturability and inspectability. To avoid expensive redesigns and large mask house cycle times it is important to find shortcomings before the data are submitted to the mask house. As an approach to the situation depicted, a (Mask) Manufacturing Rule Check (MRC) can be introduced. Aggressive Optical Proximity Correction (OPC) is a special challenge for mask making. Recently, special algorithms for mask inspection of OPC assist features have been implemented by equipment vendors. Structures smaller than two inspection pixels, like assist structures, can be successfully inspected with certain algorithms. The impact of those algorithms on mask pattern requirements and suitable MRC adoptions will be discussed in the present paper.
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