Effect of Postoxidation Annealing on Reliability of Thermal Oxides Grown on n-Type 4H–SiC(0001) Wafer

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The effects of two types of postoxidation annealing (POA) techniques on the reliability of thermal oxides grown on a 4H–SiC(0001) wafer have been investigated. Hydrogen POA at a high temperature of 800 °C is carried out for 30 min after dry oxidation at 1200 °C and it results in an improvement of the insulating properties of thermal oxides. The mode values of the field-to-breakdown ($E_{\text{BD}}$) and charge-to-breakdown ($Q_{\text{BD}}$) of thermal oxides prepared by high-temperature hydrogen POA are 10.6 MV/cm and 0.39 C/cm2, respectively. On the other hand, pyrogenic reoxidation annealing (ROA) with a water vapor content above 25% at 950 °C for 180 min adversely affects the reliability of thermal oxides. Also, it is found that the reliability of thermal oxides on a 4H–SiC wafer prepared by pyrogenic ROA degrades with an increase in water vapor content in wet ambient.
2008-01-25