PRECISION COMPARISON OF SURFACE-TEMPERATURE MEASUREMENT TECHNIQUES FOR GAAS ICS

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