Enhanced channel mobility of 4H–SiC metal–oxide–semiconductor transistors fabricated with standard polycrystalline silicon technology and gate-oxide nitridation

Effect of gate oxidation method on electrical properties of metal-oxide-semiconductor field-effect transistors fabricated on 4H-SiC C (0001) face Appl.The key stages of the dry oxidation of the SiC͑0001͒ surface are analyzed based on first-principles calculations. It is found that an abrupt SiC/ SiO 2 interface model results in a large activation barrier of oxygen penetration to the silicon carbide, and thus the penetration is probably the rate-limiting step for the entire dry-oxidation process. The subsequent reactions of SiC oxidation after oxygen penetration are investigated, and it is found that CO release is competing with carbon dimer formation. These dimers probably are responsible for near-interface traps in the silica layer generated during SiC oxidation. The possible passivation reactions of a carbon dimer defect by active species, such as O 2 , NO, and H 2 are investigated. It is found that an oxygen molecule can break a Si-C bond via dissociation in the triplet state and finally can produce two CO molecules from the carbon dimer defect. The NO molecule can easily break a Si-C bond of a carbon dimer defect and form cyano groups -CN, which can finally recombine to form a C 2 N 2 molecule. This molecule can hardly diffuse in silica matrix, and it is suggested that it is further oxidized by an NO molecule to CO and N 2 molecules. It is suggested that the process of passivation by O 2 and NO molecules is restricted by the incorporation of these molecules in small voids near the carbon defect. Based on the calculated results, a simple kinetic mechanism of dry SiC oxidation is proposed and kinetic modeling of the oxidation process is performed. It is found that in the framework of this mechanism, the carbon defect density should weakly depend on temperature.

“…48 It was shown 49 that the main influence of the nitridation is reduction of NITs. 48 It was shown 49 that the main influence of the nitridation is reduction of NITs.…”

Section: B Carbon Defect Passivation By Nomentioning

confidence: 99%

First-principles-based investigation of kinetic mechanism of SiC(0001) dry oxidation including defect generation and passivation

Гавриков

Knizhnik

Сафонов

et al. 2008

“…Recently, impressive results have been demonstrated by nitridation in nitric oxide ͑NO͒: significant improvement in gate oxide reliability, 8 increase in effective channel mobility, 9,10 and reduction in interface trap density (D it ) [11][12][13] and near-interface trap density. 14 Nitrous oxide (N 2 O) can be used as an alternative gas for nitridation, and it would be a preferred gas for use in industry because of its nontoxic property.…”

Section: Introductionmentioning

confidence: 98%

Electrical and physical characterization of gate oxides on 4H-SiC grown in diluted N2O

Cheong

Dimitrijev

Han

et al. 2003

Self Cite

A systematic electrical and physical characterization of gate oxides on 4H-SiC, grown in diluted N2O at 1300 °C, has been performed. Electrical characterization by the high-frequency C-V technique, conductance technique, and slow trap profiling method reveals that the densities of interface and near-interface traps, and the effective oxide charge for gate oxides grown in 10% N2O are the lowest, compared to gate oxides grown in 100% and 0.5% N2O. These results are supported by physical characterizations using x-ray photoelectron spectroscopy, secondary ion mass spectroscopy, and atomic force microscopy. It has been shown that carbon clusters, accumulated at the SiC-SiO2 interface, directly influence the roughness of the interface and the densities of the interface and near-interface traps.

“…Nitridation is the most common process to improve the mobility, taking reliability and stability into consideration. [4][5][6][7][8][9] Although the interface state density (D IT ) evaluated by the conventional high-low method is significantly reduced by nitridation processes, the improvement in mobility is not sufficient. Therefore, it is important to reveal mobility-limiting factors at the nitrided SiO 2 /SiC interface.…”

mentioning

confidence: 99%

Characterization of very fast states in the vicinity of the conduction band edge at the SiO2/SiC interface by low temperature conductance measurements

Yoshioka

Nakamura

Kimoto

2014

We have investigated the unique interface states (NI) generated by NO annealing at the SiO2/SiC interfaces by low-temperature conductance measurements, which is more suitable for characterization of very fast interface states than high-frequency conductance measurements at room temperature. Although only a part of the NI states can be evaluated by measurements at room temperature, the whole picture of the NI states, especially near the conduction band edge (0.07 eV ≤ EC−ET), has been revealed by the low temperature measurements. The NI peak was present at the interface even without NO annealing. The NI density increased with NO annealing temperature. The NI density at the energy levels shallower than 0.2 eV exceeded 1012 cm−2eV−1 after NO annealing. The capture cross section of the NI states is uniquely larger than that of conventional interface states.