A semiconductor process of forming metal gates with different threshold voltages includes the following steps. A substrate having a first area and a second area is provided. A dielectric layer and a first work function layer are sequentially formed on the substrate of the first area and the second area. A second work function layer is directly formed on the first work function layer of the first area. A third work function layer is directly formed on the first work function layer of the second area, where the third work function layer is different from the second work function layer. The present invention also provides a semiconductor structure formed by said semiconductor process.