Effects of etch rate on scallop of through-silicon vias (TSVs) in 200mm and 300mm wafers

The effects of etch rate on TSV sidewall variation in 8” (200mm) and 12” (300mm) wafers are investigated in this study. Emphasis is placed on the determination of sidewall scallop with different etch rates ranging from 1.7μm/min to 18μm/min and various TSV diameters (1μm, 10μm, 20μm, 30μm, and 50μm) by design of experiments (DoE). The BHE in/out (2666Pa/2666Pa) are the same for all the cases. Also, characterizations of the sidewall scallop are performed by cross sections and scanning electron microscopy (SEM). Furthermore, with a same etch recipe, mask, and 9 (5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 40μm, 55μm, and 65μm) TSV diameters, the etch results such as etch rate, TSV depth, and sidewall scallop of 200 and 300mm wafers are provided and compared, Finally, a set of useful process guidelines and recipes for optimal TSV etching is presented.