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Silicon oxynitride (SiOxNy) insulators were grown on Si substrates using O2/N2/Ar gas mixtures at room temperature and a pressure range between 5 and 50mTorr in an ECR plasma. Thickness values between 1.5 nm and 6.3 nm were determined by ellipsometry. FTIR spectrometry analyses have shown reduced nitrogen content for the oxynitrides grown at medium pressures (10-20 mTorr) as compared to those grown at 5 and 50 mTorr. Intense formation of NO molecules in the gas phase was detected by plasma spectroscopy, and this can explain the observed reduction of nitrogen content in the films due to increased nitrogen removal from the surface by NO molecules. Metal/oxynitride/Si capacitors were formed here with double metal layer structures. A 50 nm thick Ti layer, used as a barrier against Al spike formation through the dielectric, was first deposited on the oxynitride layer followed by a 180 nm Al upper layer. Double layer metal electrodes were deposited by e-beam evaporation in ultra-high vacuum (base pressure of 10-9 Torr) and patterned by a lift-off technique. C-V characteristics of Al/Ti/SiOxNy/Si samples were obtained. C-V curves were simulated by CVC software and the EOT (equivalent oxide thickness) values were determined, with values being between 0.5 and 2.9 nm. I-V characteristics were obtained and the leakage current densities between 2.9 and 6.5 A/cm2 were extracted (for gate voltage of –1 V). It was observed that: high nitrogen concentrations at the insulator/semiconductor interface can reduce the EOT and Jg values of the oxynitrides, resulting in high dielectric constant dielectrics. TEM and EDS analyses of Al/Ti/SiOxNy/Si specimens (with EOT of 0.5 nm) presented physical SiOxNy thickness of 1.5 nm and Ti contamination (from electrode) at SiOxNy layer. From C-V curve and TEM physical dielectric thickness, a high K of about 12 was estimated. Thus, this contamination modified the SiOxNy layer, indicating the ultra-thin high K gate dielectric formation with EOT of 0.5 nm. Therefore, ultra-thin oxynitrides, with EOT < 3 nm, can be grown by O2/N2/Ar ECR plasma oxynitridation (using a Ti-based gate electrode) and are suitable gate insulators for sub-100 nm MOS devices. |