US Patent 11177178 FinFETs and methods of forming FinFETs

An embodiment is a method including forming a multi-layer stack over a substrate, the multi-layer stack including alternating first layers and second layers, patterning the multi-layer stack to form a fin, forming an isolation region surrounding the fin, an upper portion of the fin extending above a top surface of the isolation region, forming a gate stack on sidewalls and a top surface of the upper portion of the fin, the gate stack defining a channel region of the fin, and removing the first layers from the fin outside of the gate stack, where after the removing the first layers, the channel region of the fin includes both the first layers and the second layers.