A study about the wet oxidation of crystalline and ion damaged 6H-SiC

This paper reports a study about the wet oxidation of crystalline and ion damaged 6H-SiC. The oxidation temperature was constant and equal to 1100 degrees C. The oxidation time ranged between 10 and 360 min. 6H-SiC wafers, n-type, Si terminated, on-axis [0001] oriented were used. Selected area of the wafer surface were implanted by Ar+ ions at 170 keV and fluence equal to 1.1 x 10(15) cm(-2). The disordered atomic fraction and the depth of the as-implanted layers, the composition and the thickness of the thermally grown oxides, and the structural quality of the BH-SIC crystal below the oxides were studied by the Rutherford backscattering (RBS) technique in channeling geometry. Some comparisons for oxidations done in a dry ambient and for wafers damaged by Ar+ at 30 keV are also presented. This study confirms that the oxidation rate of ion damaged 6H-SiC is always faster than that of Si terminated virgin 6H-SiC crystal, moreover, the presence of hydrogen in the wet ambient further accelerated the process at the ion damaged 6H-SiC surface. The structural quality of the semiconductor at the interface with the oxide is equivalent in the case of ion damaged and virgin 6H-SiC provided that all the damaged depth is consumed and the oxidation got into the bulk crystal. At the beginning of the oxidation process the swelling of the still damaged but not yet oxidised 6H-SiC produces unusual morphologic structure for contiguous oxide films on virgin and ion damaged 6H-SiC. Finally, the major factor limiting the thickness of thermal oxide on damaged area is the original thickness of the implanted layer.