Effects of nitride lightly-doped-drain spacers on inter-metal-dielectrics-induced metal oxide semiconductor field effect transistor degradation under hot carrier stress

Metal oxide semiconductor field effect transistors (MOSFETs) fabricated using various combinations of lightly-doped-drain (LDD) spacer materials (e.g. Si₃N₄ versus SiO₂) and inter-metal-dielectric (IMD) materials (e.g. silane versus tetraethoxysilane plasma-enhanced chemical vapor deposition oxide) were used to investigate the effect of IMD materials and nitride spacers on MOSFET degradation under hot carrier stress. According to the results, nitride spacers significantly enhance the hot-carrier reliability of nMOSFETs; however, the water-blocking property of nitride spacers fails to eliminate the IMD-induced device degradation. For pMOSFETs, there is negligible difference in hot carrier immunity between devices with oxide and nitride spacers.