Time-dependent compositional variation in SiO2 films nitrided in ammonia

Han, C. J.; Moslehi, Mehrdad M.; Helms, C. R.; Saraswat, Krishna C.

doi:10.1063/1.95513

Cited by 29 publications

(7 citation statements)

References 13 publications

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“…This paper follows our earlier published letter on timedependent compositional variation in SiO., films nitrided in ammonia (12). Two of the major new results reported in that letter were the quantitative observation of oxygen depletion in the nitroxide "bulk" region and the reoxidation of the interface by oxygen presumably liberated by the bulk exchange reaction.…”

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confidence: 62%

Compositional Studies of Thermally Nitrided Silicon Dioxide (Nitroxide)

Moslehi

Han

Saraswat

et al. 1985

J. Electrochem. Soc.

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The kinetics of thermal nitridation of silicon dioxide in ammonia ambient has been studied. SiO2 films of 100-1000~ thick were thermally nitrided at 950~176 for times from 15s to 2h. Our experimental results based on etch rate and Auger electron spectroscopy measurements clearly indicate the multilayer structure of nitrided-oxide films. Nitrogenrich layers are formed at the surface and interface regions at a very early stage of the nitridation process. After a few minutes, the nitridation reaction mainly goes on in the bulk region, with the surface and interface nitrogen content remaining fairly constant. The Auger depth profiles show that the interface moves away from the nitrogen-rich layer as the nitridation proceeds. In addition, our results indicate the formation of an oxygen-rich layer underneath the nitrogenrich layer whose thickness increases with nitridation time. The formation of this oxide-like layer can be attributed to a slow oxidation of the silicon substrate at the nitroxide/silicon interface by the oxygen which is a by-product of the bulk exchange reaction between NH3 (or nitrogen containing species) and SiO2. The results of this work can be qualitatively used to explain effects such as enhanced boron and phosphorus diffusion and growth of stacking faults in the silicon substrate during nitridation of oxide.

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confidence: 62%

Compositional Studies of Thermally Nitrided Silicon Dioxide (Nitroxide)

Moslehi

Han

Saraswat

et al. 1985

J. Electrochem. Soc.

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“…Vasquez et al (1984) observed an oxygen-rich region at the nitrided-oxide/silicon interface and suggested as a possible explanation that some oxidation might be taking place at the silicon surface as a result of reaction with by-products (possibly hydroxyl species) formed from reactions of NH3 with SiOz. An oxygen-rich layer was also observed in the study of Han et al (1985), who concluded that the oxygen present at the nitridedoxide/silicon interface originated as a by-product of exchange reactions in the bulk of the oxide during nitrogen incorporation. But even if oxidation does take place during nitridation of Si02, it is still necessary to come up with an explanation of why such a relatively small oxidation rate should lead to such a large interstitial supersaturation.…”

Section: 'mentioning

confidence: 73%

“…But for nitridation of an Si02 layer, if there is any consumption of the silicon surface by nitriding reactions it is apparently too small to be easily observable, and yet the interstitial supersaturations that result are at least as great as those that occur during oxidation of a silicon surface in a 100% Oz ambient. Nitrogen incorporation into the films has been studied [see, for example, the article by Han et al (1985) and references therein], but it is not clear how this would lead to self-interstitial injection into the bulk. Vasquez et al (1984) observed an oxygen-rich region at the nitrided-oxide/silicon interface and suggested as a possible explanation that some oxidation might be taking place at the silicon surface as a result of reaction with by-products (possibly hydroxyl species) formed from reactions of NH3 with SiOz.…”

Section: 'mentioning

confidence: 99%

Point defects and dopant diffusion in silicon

1989

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Diffusion in silicon of elements from columns III and V of the Periodic Table is reviewed in theory and experiment. The emphasis is on the interactions of these substitutional dopants with point defects {vacancies and interstitials) as part of their diffusion mechanisms. The goal of this paper is to unify available experimental observations within the framework of a set of physical models that can be utilized in computer simulations to predict diffusion processes in silicon. The authors assess the present state of experimental data for basic parameters such as point-defect diffusivities and equilibrium concentrations and address a number of questions regarding the mechanisms of dopant diffusion. They offer illustrative examples of ways that diffusion may be modeled in one and two dimensions by solving continuity equations for point defects and dopants. Outstanding questions and inadequacies in existing formulations are identified by comparing computer simulations with experimental results. A summary of the progress made in this field in recent years and of directions future research may take is presented.

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“…Despite the fact that the generated oxygen amount is very small (i.e. the oxidation rate is slow), the diffusivity enhancement is high as observed by Han et al [17]. He noticed that for 40 nm oxinitrides in NH 4 at 1100 C, the oxide layer formed at the interface is only 2 nm after 1 h of nitridation, but the P diffusivity increases by a factor of five which is more than twice the enhancement observed during thermal silicon wet oxidation, but the oxidation rate in this case is more than 100 times faster than that for oxinitridation [18].…”

Section: Basic Considerationsmentioning

confidence: 85%

“…The displaced oxygen diffuses towards both the surface and the SiO 2 /Si interface where it reacts with the silicon substrate. The resulting layer structure is a region with a high nitrogen content at the oxide surface, an oxinitride in the body, another nitrogen-rich thin region close to the interface with silicon, and a very thin oxygen-rich layer located at the SiO 2 /Si interface [17]. In the same way as for normal oxidation, the interstitials generated at the interface, due to the silicon oxidation reaction, move towards the silicon bulk.…”

Section: Basic Considerationsmentioning

confidence: 98%

Silicon Self-Interstitial Kinetics Study by Means of Thin Membranes under Thermal Oxinitridation

Carrillo-López

Morales‐Acevedo²

1999

phys. stat. sol. (a)

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We have made a study for determining the silicon self‐interstitial diffusivity, their equilibrium concentration and their recombination velocity at SiO2/Si and Si3N4/Si interfaces in float zone and Czochralski silicon wafers. The experiments were based on monitoring the stacking fault growth/reduction kinetics at the front surface of a silicon membrane with a SiO2 or Si3N4 thin layer on top, under constant interstitial generation, by means of an oxinitridation process, at the other side of the membrane. We show that under these experimental conditions, the analysis and interpretation of the results is direct because the transport equation can be solved in a simple manner. We have achieved a very good agreement between the experimental results and the calculations made with the model and we have been able to determine values for the interstitial diffusivity, the equilibrium concentration and the recombination velocity at the SiO2/Si and Si3N4/Si interfaces.

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Time-dependent compositional variation in SiO2 films nitrided in ammonia

Abstract: Articles you may be interested inInfluence of process parameters on the timedependent dielectric breakdown of rapid thermally nitrided and reoxidized nitrided thin SiO2

Cited by 29 publications

References 13 publications

Compositional Studies of Thermally Nitrided Silicon Dioxide (Nitroxide)

Compositional Studies of Thermally Nitrided Silicon Dioxide (Nitroxide)

Point defects and dopant diffusion in silicon

Silicon Self-Interstitial Kinetics Study by Means of Thin Membranes under Thermal Oxinitridation

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