PLATINUM ETCHING IN AR O-2 MIXED-GAS PLASMA WITH A THIN SIO2 ETCHING MASK/

Experimental studies of the etching of platinum with a SiO2 etching ma sk in an Ar/O-2 mixed gas plasma were performed. The etching selectivi ty of platinum to SiO2 increases with the addition of oxygen, and a hi gh etching selectivity of more than 6 is obtained around an oxygen con centration of 10%. This high etching selectivity is caused by the diff erence in the adsorption of oxygen atoms between platinum and SiO2. In the etching of SiO2 by an Ar/O-2 plasma, oxygen atoms are removed by sputtering by incident ions; however, these vacant sites of oxygen are filled immediately by the oxygen atoms incident from the plasma. The surface etching of SiO2 in an Ar/O-2 plasma is disturbed by these repl acements of the oxygen atoms. On a platinum surface incident oxygen at oms do not stay on the surface, therefore, disturbance of the etching by oxygen adsorption does not occur, This difference in the oxygen ads orption between platinum and SiO2 is confirmed by the x-ray photoelect ron spectroscopy analysis of the etched surfaces. By using an Ar/O-2 p lasma where a high etching selectivity of Pt/SiO2 is obtained, platinu m can be etched with thin SiO, etching masks. By optimizing both the t hickness of the SiO2 mask and the etching time, platinum can be etched without any residue from the redeposition of the etching products. (C ) 1998 American Vacuum Society.