Electrical and phsyical characterization of ultrathin silicon oxynitride gate dielectric films formed by the jet vapor deposition technique

摘要

This paper describes the electrical and physical characteristics of ultrathin jet Vapor Deposited (JVD) SIlicon Oxynitride films. Capacitance-Voltage measurements indicate an equivalent oxide thickness (EOT) of less than 2 nm, taking into account the quantum-mechanical correction. These films have leakage currents almost two orders of magnitude lower than thermal oxide of the same equivalent thickness. Measurements on NMOSFETs with 0.15 mu m of channel length demonstrate excellent electrical properties, including high drive currents (approx 0.5 mA/ mu m direct a V_d chemicla bounds V_g - chemicla bounds 1.5 V), low sub-threshold swings (approx 72m V/decade), and high transconductance (approx 0.36 mS/ mu m direct a V_d chemicla bounds 1.5 V). These films wer also analyzed using a variety of physico-chemical methods, including Total X-ray Fluorescence (TXRF), Atomic FOrce Microscopy (AFM), Nuclear Reaction Analyasis (NRA), Low Energy (500 eV0 Secondary Ion Mass Spectrometry (SIMS), and Transmission Electron Microscopy (TEM). Surface metal concentrations of less than 10~(11) atoms/cm~2 were measured from the EXRF analysis. The micro-roughness values for these films varied between 0.15-0.17 nm as measured by AFM. Low energy (500 eV) SIMS and NRA indicate high (N) near the top as well as throughout the bulk of the film, and a significant amount of (O) near the top o f the film. High Resolution TEM pictures show a very uniform film with a physical thickness of 2.8 +- 0.1 nm, which yields and effective dielectric constant of 5.5, consistent with these types of oxynitride films.