Oxidation of silicon nitride films in an oxygen plasma

Abstract

The fabrication of oxynitrides using low thermal budget process technology is a key component in the production of advanced devices. This work focuses on the use of plasma anodization of low-pressure chemical vapor deposition (LPCVD) silicon nitride films to produce silicon oxynitride films, which are characterized structurally and electrically. The oxynitride dielectric films have a three layer structure, with “SiO2”-like layers at the surface and near the interface, and a “Si3N4”-like layer between them. Hence, nitrogen atoms are replaced by oxygen atoms at the surface of the film and near the Si/dielectric interface. The conductivity of the silicon nitride film was found to be higher than the silicon oxynitride film, whereas the conductivity of the oxynitride and, therefore, its trapping characteristics are more temperature dependent. Furthermore, the activation energy required to release an electron from a trap in the silicon oxynitride film (0.218 eV) is 1.7× that of the silicon nitride film (0.130 eV). Although oxidation of the LPCVD silicon nitride film did not reduce the interface trap density (≅1012 cm−2 eV−1 for both Si3N4 and SiON films), the density of traps, which are thought to be silicon dangling bonds in the form of an sp3 state near midgap, have reduced. A model to explain the conduction properties of the silicon oxynitride film—based on the Fowler–Nordheim conduction mechanism—was developed. Moreover, this model takes into account the trapping dynamics of the film. It was found that the best theoretical fit to the experimental current density data was obtained by assuming that the areal trap density, No,=5×1012 cm−2 and the trap capture cross section, σ=1×10−16 cm2.

Effect of alloying temperature on the capacitance–voltage and current–voltage characteristics of low‐pressure chemical vapor deposition SiNx/n‐GaN MIS structures

“…(b) and (d), the conduction bulk trap depth can be calculated to be 1.02 and 1.18 eV, respectively for samples A and B, which are very close to values of some other reports . A Poole–Frenkel conduction bulk trap depth of 0.809 eV was reported in the as‐grown stoichiometric SiN x by LPCVD at 780 °C . After alloying at higher temperature, the PF trap depth becomes larger, which is also observed by others .…”

On the scaling issues and high-κ replacement of ultrathin gate dielectrics for nanoscale MOS transistors

“…Oxynitride prepared by NH 3 nitridation would introduce a large amount of traps because of the hydrogen incorporation and the amount of nitrogen incorporation at high temperature (>1000°C) is still too low (<5%) [70,71,[85][86][87] to improve the j value. With the advantages of low hydrogen content and the selflimited low growth rate, N 2 O oxide permits a better control of film thickness and slightly increases the resistance to boron diffusion [88][89][90][91][92][93][94][95][96][97][98][99][100][101][102][103][104][105].…”

Ultrathin silicon oxynitride formed by low-energy electron impact plasma nitridation and chemical oxidation methods

“…It is well known that in the practical use of SiO 2 layers as gate insulators, the following obstacles arise: ͑i͒ penetration of boron from poly-Si gate electrodes to SiO 2 and Si and ͑ii͒ high-density leakage current. 4 Several methods have been developed for the formation of silicon nitride and silicon oxynitride layers including ͑i͒ direct nitridation of silicon or SiO 2 using thermal reactions with NH 3 , NO, or N 2 O gas, 4,5,7-9 using plasma-assisted techniques, 10,11 and using an implantation method, 12 and ͑ii͒ deposition of silicon nitride or silicon oxynitride layers using plasma enhanced chemical vapor deposition, 6,13 low-pressure chemical vapor deposition, 14 low-pressure rapid thermal chemical vapor deposition, 15 jet vapor deposition, 16 remote plasma enhanced chemical vapor deposition, 17 electron cyclotron radiation-assisted sputter deposition, 18 and reactive pulsed laser deposition. Nitrogen-containing dielectrics such as silicon oxynitride and silicon nitride have attained much attention because besides their high r ,they show a good resistance to boron penetration 4 -6 and an improvement in the charge-tobreakdown voltage.…”