New Observations on the Uniaxial and Biaxial Strain-Induced Hot Carrier and NBTI Reliabilities for 65nm Node CMOS Devices and Beyond

Abstract

In this paper, new observations on the uniaxial and biaxial strain-induced hot carrier reliability and/or NBTI in nMOSFET and pMOSFET respectively have been reported for the first time. Uniaxial and biaxial strained nMOSFET and pMOSFET have been extensively examined. Different mechanisms are responsible for different strains in nMOSFET and pMOSFET. For the nMOFETs, it was found that uniaxial strain device has comparable HC reliability with the control device, while biaxial SiGe-strained device exhibits a much worse reliability. This is related to a large impact ionization rate in a biaxial strain which leads to a much worse reliability. For the pMOSFETs, either uniaxial or biaxial strained device shows a comparable amount of HC degradation, while SiGe S/D strained structure might be better considering process complexity, performance, and reliability. Although NBTI is still a great concern in SiGe S/D devices, embedded SiGe S/D technique can improve greatly the device NBTI reliability. These results provide a valuable guideline for the present 65nm and beyond CMOS device design with focus on the strain engineering.