A method for fabricating a test structure on a wafer includes forming a fin on a substrate, forming a first gate stack over the fin, the first gate stack having a first gate width, the first gate stack including a gate dielectric layer having a first thickness, forming a second gate stack over the fin, the second gate stack having a second gate width, the second gate stack including a gate dielectric layer having a second thickness, and forming a third gate stack over the fin, the third gate stack having a third gate width, the third gate stack including a gate dielectric layer having the second thickness, wherein the first gate stack is arranged a first distance from the second gate stack and the second gate stack is arranged the first distance from the third gate stack.