Anisotropic etching of silicon nitride at low temperatures by synchrotron radiation

Abstract

Photochemical etching of silicon nitride using synchrotron radiation was studied. The etching gas used was a mixture of SF 6 and Ar. Introduction of the reactive species produced by a 2.45 GHz microwave (MW) discharge made the etch rate in the irradiated region high. The effect of cooling the sample was investigated in the SR-excited etching using a MW discharge. The cross-sectional feature of the etched sample showed an undercut at room temperature, and this undercut is suppressed at low temperatures. It is suggested that at low temperatures the gas phase reaction is suppressed and the surface excitation reaction becomes dominant. Submicron patterning was demonstrated using a stencil mask.