Impact of uniaxial strain on random telegraph noise in high-k/metal gate pMOSFETs

The random telegraph noise (RTN) characteristics of high- k (HK)/metal gate (MG) pMOSFETs with uniaxial compressive strain have been investigated. The configuration-coordinate diagram and band diagram are both established by extracting trap parameters, including capture and emission time, activation energy for capture and emission, trap energy level, and trap location in gate dielectric. Through a comparison of RTN results and gate-leakage current density (J_G) between HK/MG pMOSFETs with and without uniaxial compressive strain in channel, it is found that the trap position from the insulator/semiconductor interface is reduced in the uniaxial compressive strained HK/MG pMOSFETs. This is reasonably attributed to the strain-increased tunneling barrier height and out-of-plane effective mass, which brings about the reduction in the tunneling attenuation length. Meanwhile, it can also be demonstrated by the lower J_G in uniaxial compressive strained HK/MG pMOSFETs.