Quantum Mechanical Charge Trap Modeling to Explain BTI at Cryogenic Temperatures

Electronics operating at cryogenic temperatures is crucial for scaling up single qubits to complex quantum computing systems. There are various studies concentrating on the characterization of advanced CMOS technologies operating at low temperatures, but so far little attention has been paid to reliability issues. Even though classical models predict BTI to freeze out, our measurements clearly reveal a significant threshold voltage degradation down to 4 K. This effect can be consistently explained by considering a quantum mechanical extension for the description of charge transitions in the transistor, which leads to an effective barrier lowering towards cryogenic temperatures. We implement this model in our reliability simulator Comphy and are finally able to fully explain BTI behaviour at temperatures down to 4 K.