High pressure chemical vapor oxidation of SiC in nitric acid vapor is reported. Higher growth rate at temperatures as low as 400 to 500°C has been achieved. The oxidation kinetics has been studied. It has been observed that the growth rate is strongly dependent on temperature, and the thickness of the oxide increases almost linearly with time within the error limits. X-ray photoelectron spectroscopy (XPS) measurement has been carried out to study the composition of the oxide. Room temperature electrical characterization (current-voltage and capacitance-voltage) has been carried out to estimate the oxide breakdown field strength, oxide charges, and interface state density. It is observed that prolonged oxidation or oxidation at higher temperature in acid ambient deteriorates the quality of oxide. © 2011 The Japan Society of Applied Physics.

Nandita Dasgupta

Department of Electrical Engineering

K. Kalai Selvi

Turuvekere Sreenidhi

Capacitance voltage

Chemical vapor

Current voltage

Electrical characterization

ERROR LIMITS

High pressure

Higher temperatures

Interface state density

oxidation kinetics

oxide breakdown

OXIDE CHARGE

Room temperature

oxidation

Photoelectron Spectroscopy

Silicon carbide

Vapors

X ray photoelectron spectroscopy

Nitric acid

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High Pressure Oxidation of 4H-SiC in Nitric Acid Vapor

Japanese Journal of Applied Physics

In this paper, electrical and reliability properties of ultrathin silicon dioxide, grown by immersing silicon in nitric acid solution have been studied. It is observed that the temperature, oxidation time, and concentration of the nitric acid solution play important roles in determining the thickness as well as the quality of the oxide. Prolonged exposure to nitric acid degrades the quality of the oxide. However, it was found necessary to reduce the oxidation temperature and the concentration of nitric acid to grow oxide of thickness < 2 nm. In these conditions, the leakage current and fixed oxide charge in the chemical oxide were found to be too high. However, when this chemical oxidation was followed by anodic oxidation using ac bias, the electrical and reliability characteristics of metal-oxide-semiconductor (MOS) devices showed tremendous improvement. MOSFETs with gate oxide grown by this technique have demonstrated low subthreshold slope, high transconductance and channel mobility. It is thus proposed that chemical oxidation followed by ac anodization can be a viable alternative low-temperature technique to grow thin oxides for MOS application. © 2007 IEEE.

IEEE Transactions on Device and Materials Reliability

Electrical and reliability characteristics of MOS devices with ultrathin SiO2 grown in nitric acid solutions

Microelectronic Engineering

Thin silicon oxide films on N-type 4H–SiC prepared by scanning frequency anodization method

Journal of The Electrochemical Society

Nitric Acid Oxidation of 3C-SiC to Fabricate MOS Diodes with a Low Leakage Current Density

Surface Science

Formation of atomically smooth SiO2/SiC interfaces at ∼120°C by use of nitric acid oxidation method

Investigation of 4H-SiC MOS capacitors annealed in diluted N2O at different temperatures

High pressure oxidation of 4H-SiC in nitric acid vapor

Journal	Japanese Journal of Applied Physics
ISSN	00214922
Open Access	No