Description

The Film Stress MEasurement consists of a quartz-lined chamber which is rapidly heated by high intensity, tungsten-halogen lamps. A wafer loaded into the chamber cna be heated to temperatures of 900 deg. C. Most commonly the FSM is used to measure film stress at room temperature, but it can also be used to measure stress at elevated temperatures. To avoid film oxidation effects, the chamber can e pumped to high vacujum via turbo pump or, alternatively, the chamber can be purged with nitrogen gas. In addition to stress, the FSM will also output a Wafer Bow Height value based ont eh wafer's radius of curvature. With well characterized substrates, teh film's modulus and its coefficient of thermal expansion can also be calculated.