SLOPE ETCHING OF SILICON DIOXIDE

A wet chemical process is described for the formation of sloped window edges in the selective etching of SiO2 film. Experimental results on the variation of etch rate with the temperature of the buffered hydrofluoric acid etchant are presented. The dependence of the etch profile on the etchant temperature and photoresist thickness is investigated. The slope angle θ decreases appreciably with temperature but does not depend on photoresist thickness. The low values of θ are believed to be due to the loss of photoresist bond strength around the window periphery in the presence of reactive etchant molecules. The slope etching process may ease the step coverage problem of metallization. © 1990.