| In the development of modern semiconductor industry, the device dimensions of integrated circuits are continuously scaled down to achieve higher packing density and operational speed. As the channel length decreases into deep submicrometer regime for further scaling, the short-channel effects become a major difficulty, especially in buried-channel PMOSFETs. In order to minimize the short-channel effects, p+-poly gate surface channel PMOSFETs are widely used. In addition, the short-channel effects also could be successfully suppressed by simultaneous scaling of gate dielectric thickness. However, the dramatic increase of lateral and perpendicular electric fields inside the small-geometry MOSFETs as well as the self-heating cause reliability problems such as TDDB, hot-carrier-induced device degradation, and high-temperature biased instability.; In this dissertation, various CMOS processing techniques for advanced ULSI gate oxide applications have been developed and evaluated. We have studied and compared the gate oxide reliability, device performance, and hot-carrier reliability on dual-gate CMOS devices fabricated with various processes such as standard or NO-nitrided gate oxides, polycrystalline or amorphous silicon gates, boron or BF2 implantation for p+-poly and S/D formation, and different drive-in conditions. Furthermore, the electrical and reliability characteristics of MOS devices with oxynitride gate dielectrics formed by two advanced oxynitridation techniques, i.e. anneal of thermal SiO 2 in NO-ambient (NO-oxynitride) and growth of oxynitride on nitrogen implanted Si substrates (NISS-oxynitride), have been systematically examined and compared with those of control SiO2 devices of identical thickness. An enhanced degradation under hot-hole injection as well as negative bias temperature instability (NBTI) in p+-poly PMOSFETs are observed due to the nitrogen peak at the SiO2/Si interface. A novel model of hole barrier height lowering in oxynitride gate dielectrics is proposed. The NBTI experiments performed on p+-poly PMOSFETs with different RTA drive-in temperatures conclude that, instead of boron penetration, the defects due to moisture related hydrogen contents dominate the NBTI degradation.; This research reveals a clear guideline in the process optimization to cope with boron issues and draw a potential reliability caution in the application of oxynitride as well as other advanced high-k gate dielectric materials. |
