A semiconductor device structure and a method of fabricating a semiconductor device structure are provided. A first device layer is formed over a substrate, where an alignment structure is patterned in the first device layer. A dielectric layer is provided over the first device layer. The dielectric layer is patterned to include an opening over the alignment structure. A second device layer is formed over the dielectric layer. The second device layer is patterned using a mask layer, where the mask layer includes a structure that is aligned relative to the alignment structure. The alignment structure is visible via the opening during the patterning of the second device layer.