Equipment interface: the implementation heart of APC

Many articles and presentations about advanced process control (APC) show a simple diagram where fab metrology and process tools are controlled by some APC software. What is missing from this illustration, and usually the accompanying literature, is the mention of one other important piece without which the APC scheme would not work, namely the equipment interface (EI). Trivializing the EI or overlooking its place in APC can be a costly error. The EI is the implementation heart of APC. This paper describes the history of the equipment interface project at AMD and its relationship to APC.