Reliability of Strained-channel NMOSFETs with SiN Capping Layer on Hi-wafers with a thin LPCVD-TEOS buffer layer

摘要

Recent studies have shown that the uniaxial strained channel from a contact etch-stop silicon nitride layer increases the current drivability. Such scheme is attractive and practical because it can be easily implemented using VLSI processing. The local strained channel (LSC) technique is proposed to provide tensile strained channel in nMOSFETs [1]. However, the device reliability associated with the strained device owing to the strain, and excess hydrogen and nitrogen incorporation from the deposited SiN layer is an imminent concern. In line with this, the incorporation of a thin TEOS buffer layer to improve the reliability performance has been proposed [2]. In addition, hydrogen annealed wafers (Hi-wafer) have been reported having reduced oxygen defects in Czochralski (CZ) wafers [3], with improved micro roughness and defect on the surface after high hydrogen anneal. In this study, our study focused on the reliability of nMOSFETs with LSC technique using SiN capping layer on Hi- or Cz-wafers.