ANISOTROPIC ETCHING OF SILICON-NITRIDE AT LOW-TEMPERATURES BY SYNCHROTRON-RADIATION

Photochemical etching of silicon nitride using synchrotron radiation w as studied. The etching gas used was a mixture of SF6 and Ar. Introduc tion of the reactive species produced by a 2.45 GHz microwave (MW) dis charge 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 l ow temperatures. It is suggested that at low temperatures the gas phas e reaction is suppressed and the surface excitation reaction becomes d ominant. Submicron patterning was demonstrated using a stencil mask.