The present disclosure provides an FET structure including a transistor of a first conductive type. The transistor includes a substrate having a region of a second conductive type, a channel between source and drain, and a gate over the channel. The channel includes dopants of the first conductive type. The gate includes a work function setting layer of the second conductive type. The present disclosure also provides a method for manufacturing an FET with multi-threshold voltages scheme. The method includes exposing channels of a first transistor of a first conductive type and a first transistor of a second conductive type from a first mask, doping the channels with dopants of the first conductive type, exposing channels of a second transistor of the first conductive type and a second conductive type from a second mask, and doping the channels with dopants of the second conductive type.