Patent ID: 8383437

Claim:
An etchant to etch a double layer comprising a lower metal layer comprising titanium or a metal comprising titanium, and an upper layer comprising copper or a metal comprising copper, the etchant comprising: about 0.5 wt % to about 20 wt % of persulfate, about 0.01 wt % to about 2 wt % of a fluorine compound, about 1 wt % to about 10 wt % of an inorganic acid, about 0.5 wt % to about 5 wt % of a cyclic amine compound, about 0.1 wt % to about 5 wt % of a chlorine compound, about 0.05 wt % to about 3 wt % of a copper salt, about 0.1 wt % to about 10 wt % of an organic acid or an organic acid salt, and water, wherein the etchant produces a CD skew rate of from 0.5 μm to 1 μm when etching the upper metal layer and the lower metal layer.