The present disclosure generally relates to semiconductor device fabrication and integrated circuits. More particularly, the present disclosure relates to replacement metal gate processes and structures for transistor devices having a short channel and a long channel component. The present disclosure also relates to processes and structures for multi-gates with dissimilar threshold voltages. The present disclosure further provides a method of forming structures in a semiconductor device by forming a first and second cavities having sidewalls and bottom surfaces in a dielectric structure, where the first cavity has a narrower opening than the second cavity, forming a first material layer in the first and second cavities, forming a protective layer over the first material layer, where the protective layer fills the first cavity and conformally covers the sidewall and the bottom surfaces of the second cavity, performing a first isotropic etch on the protective layer to selectively remove a portion of the protective layer and form a retained portion of the protective layer, performing a second isotropic etch on the first material layer to selectively remove a portion of the first material layer and form a retained portion of the first material layer, removing the retained portion of the protective layer, and forming a second material layer in the first and second cavities, the second material layer being formed on the retained portion of the first material layer.