WET ETCH STOP RESIST EVALUATION FOR MCM-D PACKAGING

摘要

An investigation was carried out to evaluate positive resists which would be used in subtractive etching of Cr and Cu in MCM-D applications. This resist needs to be able to withstand the alkaline and acidic chemistries used in the metal etch solutions. It must meet certain spin apply requirements in order to produce a uniform and consistent coating. It also needs to be compatible with an alkali metal hydroxide develop chemistry. Another requirement is the ability of the resist to tolerate a large soft-bake temperature range. These stipulations are, in part, necessary to provide a robust MCM thin film interconnect build process. This paper will show results collected on a variety of commercially available novolac based positive resists. Their photolithographic properties, including spin apply observations, soft bake temperature effect on unexposed developer etch rates, contrast, and minimum dose effects will be discussed. This paper will give observations on the performance of the resists in the metal etch solutions. The capability of some of these resists in Al etching will also be discussed. The results of loss of resist adhesion during Al etch will be shown. Bake parameter effects on resist adhesion in the Al etch bath will be presented. Selection of a resist to meet overall thin film MCM process requirements often involves a tradeoff between several resist characteristics. This selection process will be discussed.