Method of manufacturing semiconductor device having metal gate

A method of manufacturing a semiconductor device having metal gate, comprising:

• providing a substrate, wherein a first conductive type transistor and a second conductive type transistor are disposed on the substrate, and the first conductive type transistor comprises a first sacrifice gate and the second conductive type transistor comprises a second sacrifice gate;
• removing the first sacrifice gate of the first conductive type transistor to form a first trench;
• forming a first metal layer and a first material layer in the first trench;
• simultaneously planarizing the first metal layer and the first material layer outside the first trench;
• after planarizing the first metal layer and the first material layer, removing the second sacrifice gate of the second conductive type transistor to form a second trench without using a mask layer;
• forming a second metal layer and a second material layer in the second trench;
• and
• planarizing the second metal layer and the second material layer.