Gate dielectric properties of silicon nitride films formed by jet vapor deposition

High-quality silicon nitride (or oxynitride) films made by a novel jet vapor deposition (JVD) technique are described. The JVD process utilizes a high-speed jet of light carrier gas to transport the depositing species onto the substrate to form the desired films. The film composition has been determined to consist primarily of Si and N, with some amounts of 0 and H. MNS capacitors based on the JVD nitride films deposited directly on Si exhibit relatively low densities of interface traps, fixed charge, and bulk traps. The interface traps at the nitride/!?8 interface exhibit different properties from those at the SiO,/Si interface in several aspects. In contrast to the conventional CVD silicon nitride, the high-field I-V characteristics of the JVD silicon nitride fit the Fowler-Nordheim tunneling theory over 4-5 orders of magnitude in current, but do not fit at all the Frenkel-Poole transport theory. This is consistent with the much lower concentration of electronic traps in the JVD silicon nitride. Results from the carrier separation experiment indicate that electron current dominates the gate current with very little hole contribution. Both theoretical calculation and experimental data indicate that the gate leakage current in JVD silicon nitride is significantly lower than that in silicon dioxide of the same equivalent oxide thickness. Compared to their MOSFET counterparts, MNS transistors exhibit reduced low-field transconductance but enhanced high-field transconductance, perhaps due to the presence of border traps.