Figure 1 indicates the set of services required of the PHD, and shows its relationship with the Physical Layer (PHY), Cable Plant and Station Management (SIT). In summary the services Comprise: 1 4 ABSTRACT A new design of fully FDDI-compliant, fiber optic transceiver is described. It uniquely implements the full proposed ANSI Fiber Distributed Data Interface, Physical Medium Dependent (PMD) function, in a very compact single piece integrated package.

A cost effective wafer stepper system, the ArF MicroStep, has been developed for photoresist and process development at design rules of 0.18im to 0.l3Mm using a 193nm excimer laser illumination source. Development of the ArF MicroStep system was driven by customer requirements for a high numerical aperture exposure tool, with its configuration, specifications and development mutually conducted between IC manufacturers, Integrated Solutions, Inc., (151), and related equipment suppliers. The system was specifically designed for compatibility with imaging below 0.18jim and is configured with a 10 : 1 catadioptic reduction objective, having variable numerical aperture from 0.4 to 0.6. During the manufacturing cycle, the ArF MicroStep and its reduction optics were characterized independently and verified to perform within the requirements of the overall system. Final system integration and test permitted verification of performance through exposures in photoresist. Exposures in a single level resist have demonstrated greater than 0.4im depth of focus for 0. 16tm features over the exposure field ofthe system, with dense structures down to 0.l4im resolved by the ArF MicroStep. Using a top surface imaging process, 0.6tm depth of focus has been demonstrated for 0. l6pm geometries, with dense structures down to 0.15m resolved.

A new software option was developed for GCA wafer steppers which enables the site -by -site alignment system to be used as an automatic tool for stepper self -calibration and grid-matching. This software, called grid standardization, permits the use of ideal wafers to self -tune the stepper grid to a standard via site -by -site alignment prior to stepping product wafers. In this paper, the potential of this improved method of global alignment for use in VLSI circuit production is assessed by analyzing its various sources of misregistration.A mathematical model is developed which allows registration accuracy to be predicted for a given set of processing conditions.

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