Autonomous on-wafer sensors for process modeling, diagnosis, and control

This paper explores the feasibility of constructing an autonomous sensor ar ray on a standard silicon wafer. Such a sensor-wafer would include integrat ed electronics, power, and communications, and would be capable of being pl aced into a standard production process step, or short sequence of steps. D uring the processing of the sensor-wafer, various process parameters would be measured and recorded. There are several uses for such a sensor wafer, i ncluding equipment characterization and design, process calibration, and eq uipment qualification and diagnosis. In this paper, various sensor architec tures, power supplies, communications methods, and isolation techniques are discussed, and particular choices are made. Several proof-of-concept desig ns that measure film-thickness and temperature are discussed, and test resu lts are reviewed for each design.