Failure analysis of GaAs microwave devices with plastic encapsulation by electro-optical techniques

•GaAs devices technology used for space applications failed before the required 1000h of the THB standard aging test.•Gate-source reverse bias is the most severe stress condition for transistors and capacitors are the most critical parts.•We propose an original method to analyze plastic encapsulated devices by combining different electro-optical techniques.•We implemented backside failure analyses of encapsulated devices by using the transparency of GaAs to infrared wavelengths.•This methodology enables to make the link between electrical failure signatures and physical defects of GaAs devices. GaAs devices technology used for space applications have failed before the required 1000h of the temperature humidity bias standard aging test. The results have shown that gate-source reverse bias is the most severe stress condition for transistors and also that capacitors are the most critical parts. This paper establishes an original method to analyze plastic encapsulated devices by combining different electro-optical techniques. Many of the possible faults in ICs are linked with local heat dissipation, such as shorts between lines, oxide or junction breakdowns. Infrared thermography is based on emissivity of a material at a given temperature in relation with Planck’s law. This kind of system generates a temperature map image with a micrometric spatial resolution. Thanks to the transparency property of GaAs to near-infrared wavelengths, we propose a backside failure analysis of encapsulated devices and a precise localization of physical defects, without altering the surface. This methodology enables to make the link between electrical failure signatures and failure mechanisms of GaAs devices during aging tests.