Light induced voltage alteration (LIVA) is a semiconductor analysis

Failure analysis

Failure analysis is the process of collecting and analyzing data to determine the cause of a failure. It is an important discipline in many branches of manufacturing industry, such as the electronics industry, where it is a vital tool used in the development of new products and for the improvement...

 technique that uses a laser

Laser

A laser is a device that emits light through a process of optical amplification based on the stimulated emission of photons. The term "laser" originated as an acronym for Light Amplification by Stimulated Emission of Radiation...

 or infrared

Infrared

Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...

light source to induce voltage changes in a device while scanning the beam of light across its surface. The technique relies upon the generation of electron-hole pairs in the semiconductor material when exposed to photons.

Theory of operation

The device to be analyzed is biased using a constant current power supply. As the light source is scanned across the surface of the silicon, electron-hole pairs are generated. This causes subtle alterations of the operating characteristics of the device, which may result in slight changes to the power supply voltage. Any changes that are detected in the power supply voltage are noted and correlated with the position of the light source on the device. This allows the physical locations corresponding to power supply fluctuations to be mapped onto an image of the device. This provides the device analyst with specific locations at which the device may be examined for defects.