A semiconductor device manufacturing method includes: providing a substrate having a memory cell array area; forming a word line trench; forming a word line conductive layer in the word line trench; forming a photoresist on the substrate surface, and patterning it to protect the word line conductive layer in the contact areas but exposes the word line conductive layer outside the word line contact area, and etching the conductive layer. The resulting thickness of the word line conductive structure in the word line contact area is greater than outside the word line contact area. Thereby the opening of the word line contact hole is reduced. The depth of the window position reduces the process time in forming the contact hole, which reduces the excessive erosion of the sidewalls of contact hole having a shallower opening depth, so to avoid the device short circuit.