Efficient Modeling of Charge Trapping at Cryogenic Temperatures—Part II: Experimental
Jakob Michl, Alexander Grill, Dominic Waldhoer, Wolfgang Goes, B. Kaczer, Dimitri Linten, Bertrand Parvais, B. Govoreanu, Iuliana Radu, Tibor Grasser, Michael Waltl
Abstract
We present time-zero characterization and an investigation on bias temperature instability (BTI) degradation between 4 and 300 K on large area high- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${k}$ </tex-math></inline-formula> CMOS devices. Our measurements show that negative BTI (NBTI) on pMOSFETs freezes out when approaching cryogenic temperatures, whereas there is still significant positive BTI (PBTI) degradation in nMOSFETs even at 4 K. To explain this behavior, we use an efficient implementation of the quantum mechanical nonradiative multiphonon charge trapping model presented in Part I and extract two separate trap bands in the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer. We show that NBTI is dominated by defects in the SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer, whereas PBTI arises mainly from defects in the HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> layer, which are weakly recoverable and do not freeze out at low temperatures due to dominant nuclear tunneling at the defect site.