US Patent 7303928 Process monitor and system for producing semiconductor

A sensor on a semiconductor wafer is used as a process monitor and a capacitor is employed as a power supply for the sensor. The capacitor can be formed by stacking a poly-silicon layer and a silicon nitride layer on the wafer. A timer can be used to specify an operation time or an operation timing, etc. Furthermore, unauthorized use is prevented by storing a keyword in an ROM of the process monitor.