Developed at Sandia National Laboratories, the technique uses thermally induced voltage alteration (TIVA) and Seebeck effect imaging (SEI) to quickly find failures in ICs. The ability to scan the front and back of an IC is important because state-of-the-art ICs have up to seven layers of metal interconnections. This prevents direct observation of deeper structures from the front of the device. Additionally, flip chip or upside down packaging denies direct access to the front surface.
In the technique, the beam from an infrared laser, operating at wavelengths for which silicon is transparent, is focused on the device. The laser heats only a small part of the IC at a time. The localized heating produces a voltage change on the IC, which is biased with constant current source.