Effects of additive gases on Ag etching using inductively coupled Cl2-based plasmas

In this study, the effects of additive gases on the Ag etching were investigated using Cl-2-based inductively coupled plasmas. When Cl-2-based gases were used to etch Ag films, due to the formation of involatile, etch by-products, thick etch reaction products were remained. However, these etch by- products could be removed during the photoreist wet stripping process, therefore, various Ag removal rates could be obtained depending on the process conditions. When Cl-2 was used with N-2 and O-2, higher Ag removal rates than those by pure Cl-2 could be obtained. These results are interpreted as the increase of Cl radical due to the enhancement, of the dissociation of Cl-2 gas when N-2 was added to Cl-2 and the formations of more porous and reactive etch reaction products when O-2 was,added to Cl-2. Therefore, Ag films removal rates showed the maximum at 50 %Cl-2/50 %N-2 for Cl-2/N-2 and also at 50 %Cl-2/50 %O-2 for Cl-2/O-2. However, when Cl-2 was used with Ar, Ag removal rates was not increased with the addition of Ar possibly due to the formation of a dense etch by-product and a low sputter yield of the formed etch by-product.