4H-SiC Surface Morphology Etched Using ClF₃ Gas

Abstract

The morphology of a single-crystalline 4H-silicon carbide (SiC) substrate surface after etching by chlorine trifluoride (ClF3) gas was studied over the wide temperature range of 673-1573 K at atmospheric pressure in a horizontal cold wall reactor. The Si-face and C-face showed pitted surfaces at low temperatures; the pits tended to become small and shallow with the increasing substrate temperature. The etching for 0.5 min at the substrate temperature of 1573K and at the ClF3 gas concentration of 1% could maintain a specular surface on both the Si-face and C-face 4H-SiC, the root-mean-square roughness of which was comparable to that of the substrate before etching.

Formation and Removal of Carbon Film on Silicon Carbide Surface Using Chlorine Trifluoride Gas

“…10 For practically applying such a high rate etching technique for electronic device fabrication, the silicon carbide surface after the etching should be carefully studied. Previous studies [3][4][5][6][7][8][9] have reported that the silicon carbide surface often had a carbon film residue after the chlorine trifluoride etching. In order to obtain a silicon carbide surface without any residue, the mechanism of carbon film formation should be clarified.…”

“…For achieving the quick process, chlorine trifluoride (ClF 3 ) gas is a candidate, because it can etch the single crystalline 4H-silicon carbide at the high rate of several μm/min. [3][4][5][6][7][8][9] Additionally, the chlorine trifluoride gas could etch a large-diameter wafer using a large scale etcher. 10 For practically applying such a high rate etching technique for electronic device fabrication, the silicon carbide surface after the etching should be carefully studied.…”

Cleaning Process Applicable to Silicon Carbide Chemical Vapor Deposition Reactor

“…2 However, the cleaning of the silicon carbide CVD reactor has been widely recognized to be difficult, because the silicon carbide material is quite stable to chemical reactions, 3 even under severe conditions. In order to design the silicon carbide reactor cleaning process, the chemical reaction induced by chlorine trifluoride gas [4][5][6][7][8][9][10][11][12][13] is expected to be used, because chlorine trifluoride gas can quickly etch off singlecrystalline and polycrystalline silicon carbide at temperatures significantly lower than that for the film deposition. However, the carbon susceptor surface, covered with a silicon carbide coating film, may be significantly etched off by the chlorine trifluoride gas.…”

Repetition of In Situ Cleaning Using Chlorine Trifluoride Gas for Silicon Carbide Epitaxial Reactor

“…For this purpose, the challenging point is the way to reduce the damage to the susceptor surface to less than an allowable level. [5][6][7] The authors have studied the chemical reactions of silicon carbide with chlorine trifluoride gas [9][10][11][12][13][14][15] in order to find the possible conditions for the in situ cleaning. [5][6][7] In these studies, two kinds of depositions, such as the particle-type and film-type, could be removed by the chlorine trifluoride gas at temperatures lower than 330 • C for a long period, such as one-two hours, with an allowable damage to the susceptor coating film.…”