The Development of a Custom, Paperless Shop Floor Control System for Efficient Manufacturing

To gain manufacturing efficiencies and reduce manual overhead in our production control cycle, M/A-COM Fab II has developed a custom shop floor control system to manage wafer production. Derived and extended from our previously developed post-fab WIP system, the new fab system realizes significant labor and paper savings. The primary goal of this work was to integrate inefficient, disparate systems that controlled documents, lot recipes, lot WIP, discrepancy reporting and equipment maintenance while developing a low maintenance MES system. Major improvements have included automatic presentation of temporary or permanent document changes to the operators by events triggered by lot movement in the production system, negating the need to manually distribute document change notices throughout the facility. The equipment PM system allows tracking of numerous PM events for each piece of equipment by either time or wafer count, which allows for better matching between wafer volume demands and routine maintenance. Given past experience with other systems, strong focus was put on developing a system with an efficient user interface and minimal system maintenance requirements. We are experiencing significant time savings through out the fab; as an example, many production control jobs that used to take 30 minutes now take less than 1 minute. PAST HISTORY Before FabII was purchased by M/A-COM, the fab(as part of Cray) was controlled by a UNIX-based system called CAMEO. CAMEO was based on Oracle running on a Unix server with dumb terminals located throughout the fab. For the last 3 years, FabII has been running on text based PROMIS. PROMIS AND CAMEO were good WIP tracking systems, but were not great database systems. Data collection, retrieval and correlation were inferior and required custom bolt-on solutions. Both of these systems required paper travelers, off-line data collection and had very high barriers to integration with other systems. Both systems were also text based and required a great deal of key-stroking. However, many years of experience with both CAMEO and PROMIS have helped to define our needs and better educate us about what should be possible in a WIP system. GOALS Before beginning down the path of developing our own WIP system we laid out a number of goals for this project. The primary goals were: A) Go paperless in order to reduce the high maintenance costs of 25+ page lot travelers; B) Integrated in-line data collection (film thickness, run numbers, etc); C) On-line ECN and ISO documentation to provide instant updates and eliminate paper distribution manpower; D) Integrate previously disconnected systems such as equipment maintenance functions and PM schedules; Inventory/WIP reporting; and Product Discrepancy (PDN) reporting; E) Build a graphical, intuitive, easy-to-use system that has a short learning curve; and F) Design a system that requires minimal database and code maintenance. Although we stood to gain many benefits by developing our own system, we were careful to avoid many of the pitfalls associated with a custom system. We used with commercially standard software and the leading database software. As we are not immune to personnel attrition, the system is low maintenance and the code is accessible and fully documented. SYSTEM DEVELOPMENT The WIP system has been developed to run in a standard client-server architecture. The primary database for this system is Oracle 8.0.5 running on a Windows NT server. The server is dedicated to running the database and has redundant hardware including dual processors, RAID 5 HardDisk storage and dual power supplies. The client machines are standard WINTEL machines running Windows95,NT or 2000. The client software was written in Microsoft Visual Basic 6. A number of Active-X plug-ins were purchased to provide additional functionality for charting, reporting and document viewing. These plug-ins are relatively cheap (~$500) and often save weeks of development time. Database operations were performed in Oracle PL/SQL where possible to reduce network traffic and improve overall performance. The Oracle database has been specifically designed to minimize the need for any routine table maintenance and should only require standard backups. In order to reduce database search times for routine transactional queries, tables were developed that hold information only for the lots that Copyright © 2001, GaAs MANTECH, Inc.