SYNCHROTRON-RADIATION-EXCITED ETCHING AND TOTAL ELECTRON YIELD MEASUREMENT OF SILICON AND SILICON-NITRIDE

Photochemical etching of silicon and silicon nitride using synchrotron radiation (SR) was studied in the presence of reactive species produc ed by a 2.45-GHz microwave discharge in a mixture of SF6 and Ar. SR ir radiation enhanced the etching reaction. The difference in patterning was investigated by using two kinds of SR that have different energy d ispersions. It was found that the effect of SR irradiation is to achie ve area-selective etching on the sample surface and SR with shorter wa velength is useful for achieving a clear pattern transfer. The increme nts of the etched depth due to monochromatic SR irradiation depended o n the photon energy and were compared with the total electron yield (T EY) spectra. The etch rate for the increments was found to be almost p roportional to the light absorption of the sample fully exposed to rea ctive species. It was suggested by TEY measurements that a fluorinated overlayer is formed on the sample surface during etching. (C) 1995 Am erican Vacuum Society.