Recovery Method of Pyrolytic Carbon Surface after Exposure to Chlorine Trifluoride Gas

Lowest Concentration of Chlorine Trifluoride Gas for Cleaning Silicon Carbide Chemical Vapor Deposition Reactor

“…Thus, the overall chlorine trifluoride gas lower than 1% has various practical advantages, while the total Figure 7. R-values after the exposure to chlorine trifluoride gas at various conditions in previous studies [11][12][13] and this study.…”

“…The R-values obtained in this study were compared to those reported in previous studies. [10][11][12][13] The circles and triangles in Fig. 7 are those obtained by exposure of the bare PPyC surface to the chlorine trifluoride gas at 100% and 50 sccm for 10 min at temperatures of 300 °C-570 °C.…”

“…The recovery was considered to be caused by the outdiffusion of fluorine and by the significantly shallow and weak oxidation of the damaged layer to produce volatile carbon oxides. 13 In order to avoid any small pit formation at the PPyC surface after the annealing in the ambient nitrogen containing 0.015% oxygen at 900 °C, 13 the annealing temperature was reduced to 845 °C with adjusting the oxygen concentration in the ambient nitrogen.…”

“…A cleaning process should be developed accounting for the etching of the deposited materials and the measure to protect the susceptor from the etching. The cleaning process for the silicon carbide CVD reactor has been developed [4][5][6][7][8][9][10][11][12][13] using chlorine trifluoride (ClF 3 ) gas and purified pyrolytic carbon (PPyC) as the cleaning gas and the anticorrosive coating film of the carbon susceptor, respectively. In a previous study, 12 the particle-type silicon carbide CVD film was found to be quickly detached from the PPyC surface during the early stage of the cleaning, such as within 2 min, using the 100% chlorine trifluoride gas.…”

“…The recovery method of the PPyC coated materials after exposure to the chlorine trifluoride gas also requires the use of the susceptor for a long time. The annealing at 900 °C in ambient nitrogen slightly containing oxygen at less than 1% was reported to be effective for recovering the PPyC surface, 13 while it often caused small pits on the PPyC surface. This recovery technique should be implemented in the cleaning process, along with adjusting the conditions for suppressing the small etching pits formation of the PPyC surface.…”