US Patent 10424588 Cutting metal gates in fin field effect transistors

A method includes providing metal gate structures in a first and a second region, respectively, of a semiconductor substrate, simultaneously cutting the metal gate structures by a two-step etching process to form a first and a second trench in metal gate structures of the first and the second region, respectively, and filling each trench with an insulating material to form a first and a second gate isolation structure. Each step of the two-step etching process employs different etching chemicals and conditions. The metal gate structures in the first region and the second region differ in gate lengths and composition of gate electrode.