Lock-in averaging for semiconductor diagnostics

A system comprising:

• a first signal generator configured for switching a semiconductor device on and off at a first frequency,
• an irradiating device,
• a second signal generator configured for switching the irradiating device on and off at a second frequency,
• a camera configured for acquiring images of the semiconductor device,
• a first lock-in device configured for lock-in averaging the images with a first reference signal having the first frequency and a first phase to obtain amplitudes indicative of temperatures at a surface of the semiconductor device and/or to obtain phase signals indicative of a depth location of one or more defects in the semiconductor device, wherein the amplitudes and the phase signals are induced by the switching of the semiconductor device on and off, and
• a second lock-in device configured for lock-in averaging the images with a second reference signal having the second frequency and a second phase to obtain a topography of the surface of the semiconductor device,
• wherein the first frequency is different from the second frequency and/or the first phase is different from the second phase.