A comparative study on the channel hot-carrier degradation of N and P-MOSFETs with CVD tungsten polycide gate

The channel hot-carrier induced degradation of polysilicon (PolySi) and tungsten polycide (WSi_x) gate nMOSFETs and pMOSFETs are studied using the charge-pumping (CP) technique. WSi_x nMOSFETs under maximum substrate current (I_sub,max) stress (V_g≃V_d/2) are degraded to a smaller extent when compared to the PolySi nMOSFETs. From the CP measurements, it is confirmed that fewer interface traps (N_it) are generated for the WSi_x devices. However, under maximum gate current (I_g,max) stress (V_g=V_d), the WSi_x nMOSFETs showed higher degradation than the PolySi devices. In contrast, WSi_x pMOSFETs showed higher degradation when compared to the PolySi devices under both the I_g,max and I_sub,max stresses. The CP results showed that more N_it and N_ox (negative oxide trapped charges) are present in the WSi_x pMOSFETs when compared with the PolySi devices. Finally, the operation of WSi_x CMOS transistors is found to be limited by the hot-carrier lifetime of WSi_x pMOSFETs