PRECISION COMPARISON OF SURFACE-TEMPERATURE MEASUREMENT TECHNIQUES FOR GAAS ICS

Surface temperature measurement technology for GaAs integrated circuits (IC's) is one of the most fundamental for investigating thermoreliability relationships, but has not yet been established. We have carefully examined the three predominant techniques and have compared their precision quantitatively. Although infrared microscopy was found to lack precision more than was previously believed, a measurement procedure with high accuracy has been successfully established based on the diode drop technique, an electrical method, and the transition point technique: a liquid crystal method. The latter has been determined to have a precision as great as +/-2-degrees-C for measuring the actual hot spot of nonsealed GaAs IC's. The former is the only method which is useful for sealed IC's. Though it cannot provide the actual hot spot information, an accurate temperature with at most +/- 1-degrees-C error has been obtained at 15 mum from the spot by utilizing small sized (3.0 mum by 1.5 mum) diodes.