US Patent 10170484 Integrated circuit structure incorporating multiple gate-all-around field effect transistors having different drive currents and method

In a method of forming a structure with field effect transistors (FETs) having different drive currents, a stack is formed on a substrate. The substrate is a first semiconductor material and the stack includes alternating layers of a second and the first semiconductor material. Recess(es) filled with sacrificial material are formed in certain area(s) of the stack. The stack is patterned into fins and gate-all-around (GAA) FET processing is performed. GAAFET processing includes removing sacrificial gates to form gate openings for GAAFETs and removing the second semiconductor material and any sacrificial material (if present) from the gate openings such that, within each gate opening, nanoshape(s) that extend laterally between source/drain regions remain. Gate openings for GAAFETs where sacrificial material was removed will have fewer nanoshapes than other gate openings. Thus, in the structure, some GAAFETs will have fewer channel regions and, thereby lower drive currents than others.