NBTI(NegativeBiasTemperatureInstability)andPBTI(PositiveBiasTemperatureInstability)arecriticalreliabilityconcernsinHigh-KMetalGate(HKMG)transistortechnologies.NBTIoccurswhenanegativevoltageisappliedtothegateofapMOStransistoratelevatedtemperatures,leadingtothresholdvoltage(Vth)shiftanddegradationovertime.ThisisprimarilycausedbyinterfacetrapgenerationandchargetrappingintheHigh-Kdielectric.PBTIaffectsnMOStransistorsunderpositivegatebiasandhightemperature,alsocausingVthinstability.InHKMGstacks,PBTIismainlydrivenbyelectrontrappingintheHigh-Klayer,whichbecomesmorepronouncedwithscaling.Bothmechanismsimpactdeviceperformanceandlong-termreliability,makingthemkeychallengesinadvancedCMOStechnologies.Mitigationstrategiesincludematerialoptimization,processimprovements,andcarefulcircuitdesign.
