A system and method is disclosed for measuring a germanium concentration
in a semiconductor wafer for manufacturing control of BiCMOS films.
Germanium is deposited over a silicon substrate layer to form a silicon
germanium film. Then a rapid thermal oxidation (RTO) procedure is
performed to create a layer of thermal oxide over the silicon germanium
film. The thickness of the layer of thermal oxide is measured in real
time using an interferometer, an ellipsometer, or a spectroscopic
ellipsometer. The measured thickness of the layer of thermal oxide is
correlated to a germanium concentration of the silicon germanium film
using an approximately linear correlation. The correlation enables a
value of the germanium concentration in the silicon germanium film to be
provided in real time.