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This paper studies the operational logic in an inter-bay automated material handling system (AMHS) in semiconductor wafer fabrication. This system consists of stockers located in a two-floor layout. Automated moving devices transfer lots between stockers within the same floor (intrafloor lot transfer) or between different floors (inter-floor lot transfer). Intra-floor lot-transferring transports use a tworail one-directional system, whereas inter-floor lottransferring transports use lifters. The decision problem consists of selecting rails and lifters that minimize average lot-delivery time. Several operation rules to deliver lots from source stocker to destination stocker are proposed and their performance is evaluated by discrete event simulation.

A unique structure for chronically implantable cortical electrodes using polyimide polymer was devised, which provides both flexibility between brain tissues and skull and stiffness for easy insertion. The fabricated implants are trishanks with 5 recording sites (20 x 20pm) and 2 vias per electrode of 40 x 40pm. Each recording site was connected to the external circuitry via a 15-channel connector, which is especially designed to facilitate processing of neural signals to the external circuitry. Measured impedance values are in -2Mohm at 1KHz. For a 5pm thick silicon backbone electrode, the stiffness was improved IO times larger than that of the electrode without silicon backbone layer. Stiff electrodes with 5pm and l0p.m thick backbone silicon penetrated pia of rat without buckling.

A unique structure for chronically implantable cortical electrodes based on benzocyclobutene (BCB) biopolymer was designed to perform intracortical and extracortical neural recording simultaneously in basic neuroscience research using animal models. It was fabricated on silicon wafer using standard planar CMOS surface microfabrication technique. Dry-etchable BCB was used to insulate the electrode and provide flexibility for micro-motion compliance between brain tissue and skull. This electrode is also designed to ease the handling and implantation during the surgery and to integrate buffer circuits to improve the signal-to-noise ratio. The reliable fabrication process was developed to improve the electrode yield and performance. A 15 microm thick tungsten layer was sandwiched in the electrode tip to improve the stiffness for easy insertion during the surgery. The fabricated electrodes have two intra-cortical recording sites (20 x 20 microm) in the tip penetrating into the cortex and two epidural recording sites (80 x 80 microm) on each side wing, providing a 6 channel system. One via (40 x 40 microm) was also incorporated in the tip to balance the tip and provide the bio-seeding to improve the implants and neural tissue interaction. The acute surgical testing suggests that this electrode structure can penetrate the pia into the cortical tissue without damaging the electrode.

a neural sensor with novel structure and capable of double side recordings has been designed and fabricated using surface micromachining technique. Dry-etch Benzocyclobutene (BCB) was selected as the substrate and packaging material for its excellent electrical, mechanical and thermal properties. Positive photoresist (AZ4620) was used as the sacrificial layer during the formation of backside recording sites, and the lift-off process combined with BCB dry etch technique was developed to open the recording sites on the backside. The finished device has intracortical recording sites on both sides, and also epidural recording sites on the front side. The total channel number doubled compared to that of single side electrode structure. Three dry-etch BCB layers were applied to insulate the front side conduction traces from the backside trace layer, and package the entire devices. The developed process shows reliable and high fabrication yield, and results suggest that this newly developed neural sensor could improve the performance and efficiency of neural recording.