Optimizing roughness of plated copper sub assemblies through oxide alternative process

This paper discusses the investigation and testing to better understand the effect of baking plated copper sub-assemblies before Oxide Alternative process. Previous documented work had discussed the benefits of baking electroplated copper before Sulfuric acid and Hydrogen Peroxide type micro-etches including "Oxide Alternatives". This paper focuses on achieving consistent etch rates and improving the consistency and uniformity of the resulting copper surface morphology by baking electroplated copper sub-assemblies to anneal the copper before Oxide Alternative Process. We have seen that different types of electroplated copper and plating conditions react differently when measuring etch rates with various hold times at room temperature after plate and also with baking after plating. Etch rates were measured and compared using standard weight loss coupons and plated copper coupons. Copper surface roughness was measured using Zygo Light Interferometer.