US Patent 10049876 Removal of trilayer resist without damage to underlying structure

A method for semiconductor processing includes forming a trilayer resist structure having a middle layer disposed between a top layer and a bottom layer. The top layer is removed from a first region to expose the middle layer in the first region, and the middle layer and the bottom layer are removed in the first region to expose a structure to be processed. The top layer in a second region is also removed with the bottom layer in the first region. The first region is filled to protect the structure in the first region. The middle layer is removed in the second region while the first region remains protected. The structures in the first region and structures in the second region are exposed.