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

This paper explores the feasibility of constructing an autonomous sensor array on a standard silicon wafer. Such a sensor-wafer would include integrated electronics, power, and communications, and would be capable of being placed into a standard production process step, or short sequence of steps. During the processing of the sensor-wafer, various process parameters would be measured and recorded. There are several uses for such a sensor wafer, including equipment characterization and design, process calibration, and equipment qualification and diagnosis. In this paper, various sensor architectures, power supplies, communications methods, and isolation techniques are discussed, and particular choices are made. Several proof-of-concept designs that measure film-thickness and temperature are discussed, and test results are reviewed for each design.