Reliability evaluation on dual-etch-stop InGaAs PHEMTs

Pseudomorphic high electron mobility transistor (PHEMT) technology has been widely used in microwave switches and power amplifiers (PAs) for telecommunication applications. Because of its higher charge density and greater saturated electron velocity in InGaAs channel compared with GaAs used in MESFETs, the PHEMT exhibits lower insertion loss in switch, and higher power gain and added efficiency in PA operations. However, due to the 2-D nature of InGaAs channel in PHEMT, most of its electrical parameters are much more sensitive to the recess depth in comparison with that from traditional MESFET technology. The use of etch-stop material under the gate metal will greatly improve the precise control of gate recess and simplify process steps. This paper presents the results and detailed analysis of on-wafer-level accelerated DC and RF biased stress test and three-temperature thermal stress lifetest on our 0.9 μm Dual-Etch-Stop (DES) PHEMT process. High-temperature-operating-life (HTOL) test on single-pole-double-throw (SPDT) switch products using this DES PHEMT process has also been performed. Our report describes the reliability experiments and compares the reliability results of this new DES PHEMT process against the standard non-etch-stop (NES) PHEMT baseline material. Statistical analysis derived an activation energy E_a = 1.4 eV and an MTTF > 10⁷ hours at 125°C.