Novel technique to pattern silver using CF4 and CF4/O-2 glow discharges

Silver is being studied as a potential metal for future interconnects in in tegrated circuits. Under appropriate conditions, Ag thin films can be remov ed at reasonable rates using a CF4 or CF4/O-2 glow discharge followed by a conventional resist strip process. This is not a typical "dry-etch'' proces s where the formation of volatile products is the main removal mechanism. R ather, it is novel in that the glow discharge is employed to form reactive byproducts of Ag. There are simultaneous sputtering and desorption of the b yproducts during the plasma exposure; but the primary film removal mechanis m is in the subsequent resist strip process. Two-level-factorial design, an d one-factor-at-a-time experiments are employed to study the effects of pro cess conditions on the etch rate, and postetch surface roughness. It is fou nd that Ag removal rate in CF4 or CF4/O-2 glow discharges depends strongly on applied power. Postetch surface roughness depends on both power and pres sure. (C) 2001 American Vacuum Society.