Papers by Keyword: Chlorine Trifluoride Gas

Abstract: For improving the productivity of the semiconductor silicon carbide power devices, a very large diameter wafer process was studied, particularly for the non-plasma wafer etching using the chlorine trifluoride gas. Taking into account the motion of heavy gas, such as the chlorine trifluoride gas having the large molecular weight, the transport phenomena in the etching reactor were evaluated and designed using the computational fluid dynamics. The simple gas distributor design for a 200-mm-diameter wafer was evaluated in detail in order to uniformly spread the etchant gas over the wide wafer surface.

Abstract: A 50-mm diameter silicon carbide wafer thinning technique by means of a chemical reaction using a chlorine trifluoride (ClF₃) gas was studied accounting for the gas distributor design and the total gas flow rate. The entire etching depth profile could become uniform with the increasing total gas flow rate at the fixed chlorine trifluoride gas concentration. A relationship between the pinhole arrangement of the gas distributor and the local etching rate profile was clarified by comparing the quick calculation and the measurement.

Abstract: 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.

Abstract: A reactor cleaning technique for the silicon carbide (SiC) chemical vapor deposition (CVD) method has been developed using chlorine trifluoride (ClF₃) gas. The purified pyrolytic carbon film was studied as the improved coating film of the susceptor. At the temperatures up to 570 °C, the purified pyrolytic carbon film could have no serious damage after the exposure to the ClF₃ gas, to enable the high temperature and high speed cleaning.

Abstract: In order to develop the high etching rate reactor for silicon carbide, the 50-mm-diameter C-face 4H-silicon carbide wafer was etched using the chlorine trifluoride gas at 500 °C. By the deep etching, the concentric-circle-shaped valleys were formed at the positions corresponding to the radii of the pin-hole arrays of the gas distributor, as predicted by the calculation. The etching rate profile of 4H-silicon carbide was concluded to have a relationship with the local chlorine trifluoride gas supply . The wafer bow was small, even the wafer was very thin, about 160 μm thick.

Abstract: In order to develop a quick and practical cleaning process for the silicon carbide chemical vapor deposition reactor, the pyrolytic carbon-coated susceptor was used. The 30-μm-thick silicon carbide film was formed on the susceptor; the film was cleaning by chlorine trifluoride gas at 460 °C for 15 min. The remained fluorine was removed by the annealing at 900 °C in ambient hydrogen. The pyrolytic carbon surface did not suffer from any damage, because the pyrolytic carbon film surface morphology after the cleaning process was the same as that before the silicon carbide film deposition.

Abstract: A method to adjust the polycrystalline SiC etching rate was studied taking into account the chlorine trifluoride gas transport. The etching rate profile over the 50-mm-diameter SiC wafer could be made symmetrical by means of the wafer rotation. By activating and indeactivating the pin-holes at the various positions of the gas distributor, the etching rate profile could be locally adjusted.

Abstract: In order to develop a cleaning process for the silicon carbide chemical vapor deposition reactor, the susceptor coating materials are developed for protecting the susceptor from the etching by chlorine trifluoride gas. The chlorine trifluoride gas does not give a serious damage to the pyrolitic carbon film at the temperatures lower than 480 °C, at which temperature the quick and practical reactor cleaning process is expected to be possible

Abstract: 4H-silicon carbide epitaxial film was etched using chlorine trifluoride gas. The etch rate of C-face at 2-100 % and at various temperatures was 0.8 – 10 μm min^-1, which was comparable to those of the silicon carbide substrates. The surface morphology observed after the etching was very smooth, in contrast to that of the substrate showing many pits.

Abstract: The etch pits on the C-face 4H-SiC substrate was produced by chlorine trifluoride gas at various temperatures. The etch pit density showed the comparable value to the current dislocation density level of the Si-face 4H-SiC, when the etching was performed around 713 K. Thus, the etch pit density obtained by this technique is expected to reveal the crystal quality.