ESD (Electrostatic Discharge)/EOS (Electrical Overstress) Susceptibility of a Class of Bipolar RF Power Transistors: Experimental Studies on Stripline-Opposed Emitter Transistors

摘要

Susceptibility of a class of bipolar RF power transistors (known as stripline-opposed emitter (SOE) devices) to electrical overstressing (EOS) is studied. By virtue of having unique packaging compatible for RF/stripline applications, SOE devices pose prominent/extended exteriors for static propensity and hence are critically vulnerable to damages/degradation as predictable by the charge-device modeling. As such, contrary to the popular notion that rugged bipolar devices are not excessively prone to ESD-based detrimental effects, SOE transistors, on the other hand, are severely vulnerable to EOS threats. It is not just the Wunsch-Bell limit of catastrophy due to PN junction burnout (under high-level zaps) that dictates the damages in the devices like SOE transistors. The entire device configuration, namely, active junction, metallization, bonding, etc., as well as the external packaging, decide the device lethality. This is demonstrated by experimental studies on a family of SOE devices by subjecting them to ESD zaps using a Human Body Simulator. The results positively indicate that their vulnerability is in excess of Class II limit specified by DOD-HDBK-263 and require specific handling precautions, lest they would pose quality control and/or field failure problems. Especially, considering these devices being extremely costly, specific ESD control efforts are rather imminent. (Author)