US Patent 7718530 Method for manufacturing semiconductor device

A method for manufacturing a semiconductor device includes forming a gate conductive layer, a first mask layer, a second mask layer, and a third mask layer over a semiconductor substrate that includes a cell region and a peripheral region. The method also includes forming a second mask pattern and a third mask pattern using a gate mask. The method further includes trimming the second mask pattern in the peripheral region to form a fourth mask pattern having a size smaller than that of the second mask pattern. Still further, the method includes removing the third mask pattern, and patterning the first mask layer and the gate conductive layer using the fourth mask pattern as a mask.