A semiconductor integrated circuit (IC) including a first fin structure having a first aqueous soluble channel layer. The semiconductor IC includes a first gate structure over the first aqueous soluble channel layer, wherein the first gate structure includes a first oxide film directly contacting the first aqueous soluble channel layer, and the first oxide film includes a first material. The semiconductor IC includes a first spacer along the first gate structure, wherein a bottom surface of the first spacer is above an interface between the first oxide layer and the first aqueous soluble channel layer. The semiconductor IC includes a second fin structure having a second aqueous soluble channel layer. The semiconductor IC includes a second gate structure over the second aqueous channel layer, wherein the second gate structure includes a second oxide film directly contacting the second aqueous soluble channel layer, the second oxide film includes a second material.