Design and implementation of a plasma area information system

A description is given of the Plasma Area Local Information System (PALIS) which provides a means to automatically collect process data directly from the equipment and interact with operators through the machines themselves. A plasma etching cell has been created which integrates data collection, data reporting, and lot verification and works in conjunction with the factory system. Operator workload is reduced, potential misprocessing is eliminated, and a database rich in processing and machine information is created. A wafer bar code-reading system, multichamber single-wafer etchers, an automated cosmetic inspection machine, and a film thickness measurement station have been combined into a cell configuration. The equipment is in different parts of the room, and thus the cell arrangement is logical rather than physical. Wafers coming into plasma etch are uniquely identified by a bar code, and processing information from the etchers and measurement machines is stored by individual wafers. All the elements carry on complex communications with an AT&T 3B2/600 minicomputer via the SEMI SECS I&II communication protocol. This cell control computer maintains lot integrity, stores process-specific information in a local database, handles interactive database queries and report generation, communicates with the high-level factory control computer, and maintains lot integrity by tracking wafers within the cell