ExPro-an expert system based process management system

The design, development and preliminary testing of ExPro, an expert-system-based process management system, is reported. This system is designed to provide process setup, monitoring, and supervisory control capabilities for applications in a real-time semiconductor manufacturing environment. ExPro is a rule-based system developed using the OPS-83 expert system language in a personal computer environment. It features a modular structure and includes an integrated analytical process simulator. The simulator is used to predict process parameters prior to processing and provide wafer state information from real-time (measured) process information when direct measurement of the state is impractical. The process selected for development and demonstration purposes was rapid thermal oxidation (RTO). Testing revealed that the accuracy of the system was within 1% of goal for the case of Si(100) wafers, but the less accurate Si(111) simulation led to much larger errors