CD uniformity is one of the most critical parameters for mask making today. The mask error factor (MEF) in lithography for features that are smaller than the stepper wavelength means that any CD error is transferred to the wafer to a greater extent than the stepper reduction factor would indicate. CD results form a new laser pattern generator, the Omega6000 product line, will be presented. The system features an acousto-optic deflection architecture specifically designed to meet the CD requirements of 180 nm photomasks. A 0.86 NA final lens provides the high resolution ofthe system. The CD control and the high resolution makes the system well suited for today's advanced photomasks.

In this paper, we present how to enhance the resolution in an optical mask metrology system. The resolution is enhanced using an inverse filter based upon a model of the optical system. The filter is implemented in software, thus we achieve a higher resolution without requiring high resolution optical design.

With the shrinking design rules for semiconductors mask data complexity increases continuously. The increasing use of oPc, which has become common for advanced masks, reinforces this trend. The requirements on data processing increase and make it a possible bottleneck. Increasing write times directly impact the cost of the photomask. These facts raise the question ofhow to design a data path that will not limit the writing speed and throughput ofa pattern generator.The Micronic Omega6000 laser pattern generators are equipped with a data path designed to meet current and future demands on pattern complexity. One of the most important properties of the data path is that it is scalable. This means that the data processing power can easily be increased to handle more complex pattern data. The main building block of the data path is a multi processor computer that performs the bulk ofthe processing. The capacity increases linearly with increasing number of processors. The use of commercial processors and operating systems make it possible to benefit from the rapid development in the processor field. Great care has been taken to eliminate any bottlenecks through the use ofhigh bandwidth data transfer throughout the data path. Hard disk storage is not used after the data processing is started in order to eliminate the impact of the relatively low bandwidth of disks.A computer model of the data path has been developed to evaluate the impact different configurations. The model uses parameters like pattern density and levels ofhierarchy to describe the input data. The data path hardware is described by modeling the processing power, storage capacity and bandwidth of each block in the architecture. The model has been matched against patterns processed by the data path. The model makes it possible to predict the capacity of future extended configurations of the architecture.Results ofpattems run through the data path will be presented and how the run times compare to the physical write times of the patterns in the Omega6000 pattern generator.

The specifications of reticles for 64 Mb and 256 Mb DRAMs (0.35 tmand 0.25 im design rules)show that the use of leading edge pattern generators is not required for all levels. By using writers optimized for the requirements of each level a lower total cost can be achieved. A laser reticle writer will be described that can be used together with a leading edge system in a mix and match mode.