Automated lot tracking and identification system

Exactly meeting agreed delivery dates and product volumes is an essential part of the relationship between semiconductor manufacturers and their customers. In the ASIC business in particular, with a multitude of part numbers and small lot sizes, this has become a major "customer satisfaction" criterion. Worldwide competition is the driving force to reduce manufacturing cycle time, especially for design verification or product qualification using express lots. To supply these high priority lots in the least possible time to the proper manufacturing equipment is a critical factor in achieving short overall cycle times. In a clean room with chase-and-bay design, many different lot storage locations are distributed throughout the fab, and since logical and physical lot location can substantially differ, manufacturing operators may spend a considerable amount of time searching for the next scheduled lot for processing. The purpose of an automated global lot tracking system is aimed at giving the manufacturing operator the ability to locate any requested lot at any time anywhere in the fab; SMST therefore labeled this project Find Lot System (FiLS). It supports true "pull mode" for production personnel, cuts down on cycle time, thus allowing for faster yield ramp-up, decreases lot mixing and misprocessing, and helps meet targeted delivery dates. The lot tracking system installed in the SMST fab had to be adapted to the existing lot transportation system, with both SMIF pods and conventional wafer boxes, and had to be integrated into the existing manufacturing execution system (MES).