Reactive Ion Etching of Copper Films in SiCl 4 and N 2 Mixture

Reactive ion etching of Cu films in SiCl 4 and N 2 is proposed for the fabrication of copper interconnection lines in LSIs. Cu films can be etched using a wafer heated to at least 250°C. Adding N 2 to SiCl 4 has two advantages. One is that it prevents the etching rate of Cu between narrow pattern spaces from decreasing because it removes organic material on Cu films near resist patterns. The other is that it forms protective films such as SiN on the side walls of Cu patterns and prevents side etching. The side wall taper is controlled by changing the N 2 flow percentage.