Scanning heterodyne interferometer setup for the time-resolved thermal and free-carrier mapping in semiconductor devices semiconductor devices

An automated scanning interferometer setup for time resolved measurement of thermal and free carrier distribution in semiconductor devices during short stress pulses is presented. The semiconductor device is probed via the thermal and free carrier induced changes in the semiconductor refractive index using a heterodyne interferometer. The setup integrates device stressing facilities, data acquisition and laser beam scanning. The time and space resolutions are 3 ns and 1.5 mu m, respectively. Different modes of interferometer configurations are discussed with respect to their application. A program for the extraction of the optical phase shift and calculation of the power dissipation density from the optical signal is also presented. The error due to measurement accuracy, as well as that introduced by the data post processing, is estimated.