No abstract

CVD WSix films have been widely employed for ultra thin gate and bit-line applications. Recently, for sub 0.5 μm technologies based on CVD WSix polycide gates and interconnects, efforts have been made to replace the silane-based deposition chemistry with that based on dichlorosilane (DCS) reduction of tungsten hexafluoride (WF6). Fluorine-contaminated gate oxides and poor film adhesion and cracking (especially after high temperature annealing/oxidation) are main characteristics of silane-based WSix which could be detrimental for fine geometries of sub 0.5 |im technologies. In this paper, the composition and structure of DCS-based CVD WSix films were studied. WSix films were deposited on 200 mm, implanted polysilicon substrates; silicide film thickness ranging from 60 to 200nm. A high temperature furnace anneal and oxidation cycle was used to examine post-oxidation film properties. SIMS, RBS and X-ray diffraction (XRD) were used to determine film composition profile, structure and texture on both as-deposited and annealed/oxidized films. Si/W uniformity through the depth of the film, for both W-rich and Si-rich interfaces, and its impact on film adhesion and cracking were studied. Also, WSix step coverage for sub 0.5 μm polycide topographies were examined.

For integrated circuits, the integrity and film quality of the final passivation layer plays an important role in the device performance and reliability. Hydrogenated amorphous silicon oxynitride (α-SixNyOz:H) films deposited by plasma enhanced chemical vapor deposition (PECVD) have been extensively used for final device passivation applications. In this paper, a detailed characterization of PECVD oxynitride process for 200 mm Si wafer processing is presented. Silicon oxynitride of various compositions were deposited by changing the amounts of silane, ammonia, nitrogen and nitrous oxide in the reactant gas stream. Ultraviolet/Visible (UV/VIS) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, Rutherford backscattering spectrometry (RBS), and refractive index measurements were used to examine the variation in physical, optical and electrical properties. A correlation is observed between the oxynitride film composition, mainly N-H/Si-H ratio, and UV transmissivity (UV %T) which is of particular interest for memory applications. Effects of oxynitride film quality on e-test parameters and device performance are discussed.