Precisional comparison of surface temperature measurement techniques for GaAs ICs

The accuracy of the three predominant techniques for measuring the surface temperatures of GaAs ICs under operation was investigated. The most important result is that the precision of commercially available computerized infrared microscopy is more limited than previously believed, especially in the case when the minimum IC element size is smaller than its spatial resolution. Some type of emissivity correction is necessary to obtain high precision. At this stage, therefore, the diode drop technique, an electrical method, and the transition point technique, a liquid crystal method, or their combination, must be used for measurement with high accuracy. The transition point technique has been determined to have a precision as great as ±2°C for measurement at the actual hot spot of non-sealed GaAs ICs. The diode drop technique is the only method which is useful for sealed ICs