Method of dry etching a1cu using sin hard mask

Abstract

A new method of etching AlCu or AlSiCu lines is described. Semiconductor device structures are provided in and on a semiconductor substrate. The semiconductor device structures are covered with an insulating layer. A layer of AlCu or AlSiCu is deposited overlying insulating layer. A silicon nitride or titanium nitride/silicon dioxide layer is deposited overlying the metal layer wherein a hard mask is formed. The hard mask is covered with a layer of photoresist which is exposed to actinic light wherein the hard mask prevents reflection of the actinic light from its surface. The photoresist layer is developed and patterned to form the desired photoresist mask. The hard mask is etched away where it is not covered by the photoresist mask leaving a patterned hard mask. The AlCu or AlSiCu layer and the barrier layer not covered by the patterned hard mask are etched away to form metal lines having an outwardly tapered profile.