A semiconductor device includes a substrate having an input/output (I/O) region, an one time programmable (OTP) capacitor region, and a core region, a first metal gate disposed on the I/O region, a second metal gate disposed on the core region, and a third metal gate disposed on the OTP capacitor region. Preferably, the first metal gate includes a first high-k dielectric layer, the second metal gate includes a second high-k dielectric layer, and the first high-k dielectric layer and the second high-k dielectric layer include an I-shape.