Chlorine Trifluoride Gas Distributor Design for Single-Crystalline C-Face 4H-Silicon Carbide Wafer Etcher

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.

Non-Plasma Dry Etcher Design for 200 mm-Diameter Silicon Carbide Wafer

“…One of the key chemical process issues for the large diameter wafer is a method for uniformly spreading the reactive gas over the wafer. Following the previous studies [7], the overall and local etching rates simply depend on the etchant gas distribution. The high chlorine trifluoride gas flow rate gives the high etching rate.…”

“…The chlorine trifluoride gas is used as the non-plasma etchant. The chlorine trifluoride gas has been well known to quickly etch the semiconductor 4H-silicon carbide wafer at 100% and 500 o C [2][3][4][5][6][7]. The maximum etching rate was tens µm min -1 .…”

“…The 200-mm-diemeter silicon carbide wafer is horizontally placed on the susceptor. The wafer is assumed to be heated from the bottom side, similar to the previous study [7].…”

“…Because the silicon carbide is mechanically hard and chemically stable, the alternative process technology to improve the process productivity should be developed. For this purpose, the highly reactive gas, such as the chlorine trifluoride (ClF3) gas [2][3][4][5][6][7], is a candidate. It may improve the throughput of the large-diameter wafer processes, when the gas and heat conditions are optimized for each wafer size.…”

Chlorine Trifluoride Gas Etching Design for Quickly and Uniformly Removing a Thick C-Face 4H-Silicon Carbide Layer

“…In previous studies [9][10][11][12] for developing the dry etcher using the chlorine trifluoride gas, the local etching rate was shown to depend on the local chlorine trifluoride gas supply, similar to the chemical vapor deposition rate. 13 The gas distributor design [9][10][11][12] have been studied based on the theoretical calculations and experiments, in order to show the concept that the etching rate profile might be the average between different wavy etching rate profiles.…”