Dual damsecene process method

The invention discloses a dual damsecene process method, which comprises the following steps of: 1, sequentially forming a first interlayer film, a trench etching stop layer and a second interlayer film on a semiconductor substrate, and performing selective etching to form an opening of a through hole; 2, depositing a light blocking protection layer to completely fill the opening of the through hole and extend to the whole surface of the second interlayer film outside the opening of the through hole; 3, forming a first photoresist pattern to open a trench forming region; 4, taking the first photoresist pattern as a mask to perform back etching on the light blocking protection layer; 5, etching the second interlayer film by taking the first photoresist pattern as a mask and the trench etching stop layer as a stop layer to form a trench; and 6, removing the first photoresist pattern and the light blocking protection layer. The process flow can be simplified, the process cost and the process time are saved, and