ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
Ultrathin nitrided oxides (7.7 nm) were reoxidized for the first time by lamp-heated rapid thermal annealing in O2 at 900–1150 °C for 15–600 s. Compositions and residual hydrogen contents in various reoxidized nitrided oxides were studied by Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS), respectively. AES analyses show that as reoxidation proceeds, the nitrogen concentration peak near the outer surface decreases rapidly, while that near the Si-SiO2 interface [N]int decreases very slowly. It is newly found that the nitrogen-rich layer near the Si-SiO2 interface moves further into the substrate as reoxidation proceeds, following a movement similar to that of the Si-SiO2 interface. As the starting nitrogen content is lowered or the reoxidation temperature is raised, the distance of the peak movement ΔdAES and the reduction of [N]int are larger. The ΔdAES is found in quantitatively good agreement with the increase of film thickness evaluated by capacitance-voltage measurements. The movements are due to the diffusion-limited interfacial oxidation. In contrast to reoxidation, annealing in N2 of nitrided oxides scarcely reduces the [N]int and does not increase ΔdAES. SIMS analyses show that as reoxidation proceeds, hydrogen concentration [H] in the film decreases monotonically. As the starting nitrogen content is lowered or the reoxidation temperature is raised, [H] decreases more rapidly. Electron trapping was monitored by flat-band voltage shift ΔVFB under high-field stress, and ΔVFB is found to decrease with the reduction of [H] following a proportional relation regardless of the fabrication condition. [H] is also reduced by annealing in N2 and the reduction is comparable to that by reoxidation.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.343095
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