Abstract: An optical monitoring of electrical characteristics of devices in a semiconductor is performed during an anneal step to detect the time annealing is complete and activation occurs. A surface photovoltage measurement is made during annealing to monitor the charge state on the surface of a substrate wafer to determine when the substrate is fully annealed. The surface photovoltage measurement is monitored, the time of annealing is detected, and a selected over-anneal is controlled. The surface photovoltage (SPV) measurement is performed to determine a point at which a dopant or impurity such as boron or phosphorus is annealed in a silicon lattice. In some embodiments, the point of detection is used as a feedback signal in an RTA annealing system to adjust a bank of annealing lamps for annealing and activation uniformity control. The point of detection is also used to terminate the annealing process to minimize D.sub.t.