The use of laser and infrared scanning techniques in reliability assurance

Abstract

Applications of the laser as a non-damaging probe of semiconductor devices are reviewed. In-focus laser and infrared scanning may be carried out over relatively large areas of these devices with the electronically controlled, mechanical scanners described here. Topograms of the response of MOS and bipolar circuits to a spirally-scanned laser beam are presented. The detection of faults, the measurement of material and device properties, and the location of the information content in memory circuits are demonstrated. The same scanners have been used to obtain infrared emissive pictures of operating devices and of the diffused regions in silicon slices. Infrared pictures can be interpreted in terms of device temperature, current distribution and material doping densities. Although the laser may be used to locate faults, it is also valuable as a means of providing signals to a circuit and of introducing a temporary anaesthetization or fault at a circuit node as an aid in the computer checking of LSI circuits. © 1979.