Thermal Nitridation of SiO2 Thin Films on Si at 1150°C

Abstract

Thermally grown silicon dioxide thin films on silicon were nitrided in 1 atm NH3 at 1150°C for various times between 10 and 240 min. The films were between 12 and 163 nm thick. Chemical kinetics severely limited the incorporation of nitrogen into the film; only the thinnest films nitrided for times longer than 90 min attained a nitrogen content near 40 atomic percent nitrogen. Secondary ion mass spectrometry indicated that nitridation either lowered or maintained the average hydrogen concentration in the film. Infrared spectroscopy demonstrated that nitridation removed silanol groups from a film which had been grown in wet oxygen. In certain films, over 99% of the nitrogen in the film was incorporated into the tetrahedral network; less than 1% of all nitrogen in the film existed as silamine groups. Nitridation increased (i) the 1 MHz dielectric constant and (ii) the electron‐trapping ability of a film; these two properties were correlated to replacement of nitrogen for oxygen in the film bulk. Creation of a nitrogen‐rich layer at the Si/film interface after 10 min of nitridation was correlated to an increase in fixed insulator charge density, Nnormalf . At nitridation times of 30 min and longer, the silicon substrate was reoxidized by water released by the nitridation of the film near the interface. Reoxidation of the silicon steadily lowered Nnormalf .

Spectroscopic analysis of Al and N diffusion in HfO2

“…It has been shown in Si/SiO 2 , that annealing in NH 3 incorporates nitrogen throughout the bulk of the oxide, while displacing oxygen from the film. 18 Regarding the Hf 4f spectra of Fig. 2(b), the arrows at the top indicate the BE shift due to Al (higher) and N (lower).…”

“…2(a). To more accurately identify differences in the Al concentration profiles, the NO profile has been replaced in favor of the 18 O profile and the Al profile of sample b and c has been plotted with the common (coincident) HfO 2 and 30 Si profiles in Fig. 9(a).…”

Electrical Properties of Fluorine-Doped Oxynitride Films Prepared by Photoillumination Liquid-Phase Deposition

“…The dielectric constant of SiON is higher than that of SiO 2 . 16 However, the equivalent dielectric constant is almost that of SiO 2 for thick films. The equivalent dielectric constant increases with decreasing the film thickness due to this multilayer series structure.…”

Microstructure of oxygen-rich silicon oxynitride

“…Here we attribute it to the Si-N stretching mode in such a specific configuration as O 3 Si-NH. The main peak becomes narrow, indicating a more order microstructure 13,17 . After annealed at 750 , the main band upshifts further to 1060cm -1 with an increase of its intensity.…”

“…The hump near 3500cm -1 at the right shoulder of the main peak is attributed to the NH 2 stretching mode 12 . Bands from 3550cm -1 to 3750cm -1 include the OH stretching modes in Si-OH (3670cm -1 ) 13 and N-OH (3570-3600cm -1 ) 14 configurations. After annealed at 600 , the main band (at 3391cm -1 ) almost keeps constant except its lower-positioned peaks (O n Si 4-n -NH n=0,1,2,3 with smaller n) at the left shoulder diminishing, NH 2 stretching mode decreases and bonds related to OH mode disappear.…”