A quick cleaning process was developed for a silicon carbide chemical vapor deposition reactor. For this purpose, the stability of the susceptor coating film made of pyrolytic carbon was evaluated by means of exposing it to 100% chlorine trifluoride gas for 10 min at various temperatures. The original surface morphology of the pyrolytic carbon film was maintained under 480 • C. The fluorine atoms incorporated into the pyrolytic carbon film were removed by annealing at 900 • C either in ambient hydrogen or in ambient nitrogen. Finally, the 30-μm thick silicon carbide film formed on the pyrolytic carbon was successfully cleaned by the chlorine trifluoride gas either at 400 • C for 30 min or at 460 • C for 15 min and by additional annealing in ambient nitrogen at 900 • Chemical vapor deposition (CVD) 1-5 is one of the most frequently used techniques for producing advanced materials. It consists of two processes, such as film deposition and cleaning. The cleaning process is necessary for removing the unnecessary film formed on the susceptor and various reactor parts other than the substrate, because such films very often emit small particles. In order to maintain a clean condition for the deposition, a cleaning process has been implemented in the CVD for producing various materials, except for silicon carbide.The semiconductor silicon carbide (SiC) film is produced by means of the CVD process. 3-5 For realizing high efficiency power devices, silicon carbide has suitable properties, 6 such as a wide bandgap, high electron mobility, high thermal conduction, and high chemical and mechanical stabilities. However, these significant chemical and mechanical stabilities often cause practical problems, particularly for the CVD reactor cleaning. Currently, the silicon carbide CVD reactor does not have a cleaning process, because the convenient non-plasma reactor cleaning gases, such as hydrogen chloride, cannot react with silicon carbide. 7 Thus, a new reactor cleaning gas and cleaning process need to be developed.For this purpose, the authors have developed the in situ silicon carbide CVD reactor cleaning process using chlorine trifluoride (ClF 3 ) gas. [8][9][10][11][12] Previous studies [8][9][10] have shown that the chlorine trifluoride gas could remove the various types of silicon carbide films formed on the silicon-carbide-coated carbon susceptor in spite of operating for a significantly long time, such as 1-2 hours. This very long time was unfortunately necessary, because the cleaning temperature must be kept low for suppressing any etching damage to the susceptor coating film made of silicon carbide. However, recently and fortunately, the pyrolytic carbon film has been found to have a very low etching rate by the chlorine trifluoride gas. 12 Thus, the combination of the chlorine trifluoride gas and the pyrolytic carbon coating film should be studied in detail for achieving a quick cleaning process which is applicable for industrial production.As an extension of our previous study, 12 this study evaluated the temperat...

The high-temperature cleaning of a silicon carbide chemical vapor deposition reactor was developed using chlorine trifluoride gas and purified pyrolytic carbon (PyC) as the susceptor coating material. The purified PyC could be exposed to the chlorine trifluoride gas without causing serious damage at temperatures up to 570°C, which was in the range providing a sufficiently high silicon carbide etching rate. The spontaneous temperature increase at the susceptor surface due to the exothermic reaction heat was moderated by means of adding nitrogen gas. Thus, the particle-type silicon carbide layer could be cleaned while preventing peeling of the purified PyC surface and obtaining a practical etching rate. Additionally, the peeled surface of the purified PyC could be recovered by annealing at 900°C in ambient nitrogen containing oxygen.

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In order to evaluate the potential of a non-plasma dry etcher for silicon carbide, a 50-mm-diameter C-face 4H-silicon carbide wafer was etched using chlorine trifluoride gas at 500 • C. The wafer deformation was sufficiently small after the repetitive etching, even though the wafer was very thin, that is, about 160-μm thick. When the wafer surface was significantly etched, concentric-circleshaped valleys were formed at the radii corresponding to the circular-shaped arrays of pinholes at the gas distributor. Because the local pattern of the 4H-silicon carbide wafer etching rate corresponded to that of the chlorine trifluoride gas supply, the etching rate distribution was determined to be mainly governed by the chlorine trifluoride gas flow. Because the surface morphology and roughness after the etching was comparable to that of the mirror-polished wafer surface, the etcher evaluated in this study was expected to have a significant potential for mirror etching. In order to reduce the electric energy loss, power electronics 1-3 is currently playing major roles and making enormous contributions over the world. The power devices have various key positions to govern and improve the overall power consumption efficiency. They will have more functions and capabilities achieved by advancing the technologies of material production and device designs.The power devices are made of semiconductor materials, 2,3 such as silicon (Si), silicon carbide (SiC) and gallium nitride (GaN). The silicon carbide power devices have been developed by many researchers and engineers due to their fascinating nature, such as a high dielectric breakdown voltage, for high voltage use. The silicon carbide power devices are actually installed and currently working in trains and vehicles.2,3 Because the power device demand will further increase in the future, the process of silicon carbide material production should be improved.The significantly hard and nonreactive properties of the silicon carbide very often make the device fabrication processes long and complex. When the wafer back side is thinned by mechanical or chemical mechanical polishing after the device fabrication, the thinning processes require several hours or more. The removal rate is still about 0.2 μm/min when the plasma and Pt catalyst are used for the polishing.4-10 For developing a high speed process, an alternative high speed process, such as chemical etching, is expected.For improving the removal rate by the chemical approach, chlorine trifluoride (ClF 3 ) gas 11-17 is expected to be useful. The chlorine trifluoride gas has been reported to quickly etch the Si-and C-faces single-crystalline 4H-silicon carbide (SiC) material at a high rate, such as 5 μm/min.11 The C-face 4H-silicon carbide could be etched while maintaining the mirror-polished surface. 11,17In order to realize an industrial-scale wafer etching process, the SiC single-wafer dry etcher has been designed, fabricated and evaluated. [13][14][15][16] In this reactor, the entire etching rate profile over the 50 mm-diamet...

The etching rate profile over the 50-mm diameter single-crystalline C-face 4H-SiC wafer by ClF3 gas was numerically evaluated by means of the numerical calculation accounting for the transport phenomena. The etching rate uniformity is expected to be improved by means of adjusting the pinhole diameter and their arrangement of the gas distributor.