Influence of substrate temperature on the etching of silver films using inductively coupled Cl₂-based plasmas

In this study, the influence of substrate temperature on Ag etching is investigated using inductively coupled plasmas. When Cl₂ -based chemistry is used to etch Ag, involatile etch products remaining on the Ag film can be observed after the etching due to the very low vapor pressure of the etch reaction products, therefore, the reaction products thicker than the thickness of Ag are obtained after the etching. Even though these reaction products can be removed in a photoresist stripper, Ag removal rate is generally very low at room temperature. However, when elevated substrate temperatures in the range from 25 to 165 °C are used, due to the enhancement of Cl transport and reaction rate, higher Ag removal rates can be obtained after the photoresist stripping even though these products are not removed in situ during the etch processing. Also, we found that, at the elevated temperatures, the ratio of remaining AgCl layer thickness to the consumed Ag layer thickness is continually decreased with increasing temperature due to the increased vaporization of Ag reaction products.