Platinum etching in Ar/Cl-2 plasmas with a photoresist mask

Experimental studies of the etching of platinum have been performed with a photoresist mask in Ar/Cl-2 plasmas. The etch rate of platinum decreased wi th addition of Cl-2, showing no enhancement of etching by Cl-2 addition. Mo reover, the etch rate of platinum was found to be independent of substrate temperature in pure Cl-2 plasmas. These results indicated that the platinum etching with chlorine-containing plasmas is proceeded mainly by physical s puttering due to incident ions, not by chemical reactions that produce vola tile etch products. Thus, in platinum etching with Ar/Cl-2 plasmas, the red eposition of nonvolatile etch products was observed to occur on sidewalls o f the photoresist mask and platinum pattern; in this situation the etched p rofiles of platinum were tapered outwardly, because the redeposited films a cted as etching masks for platinum. The thickness of deposited films on sid ewalls increased with increasing Cl-2 concentration, but they were found to be removed by wet treatment with HCl solutions. It was further demonstrate d that by optimizing the Cl-2 concentration, platinum could be etched witho ut redeposition residues on sidewalls, although the etched profiles still r emained outwardly tapered. (C) 1999 American Vacuum Society. [S0734-2101(99 )05303-8].