Patent ID: 8450180

Claim:
A method of forming a semiconductor trench, comprising: providing a substrate having a periphery area and an array area; forming a mask layer on the substrate, wherein the mask layer has a first opening to expose the substrate in the periphery area and a second opening to expose the substrate in the array area; forming a first spacer on all sidewalls of the first opening; forming a recess in the substrate in the periphery area by using the mask layer and the first spacer as a mask; forming a second spacer on all sidewalls of the second opening, and removing a portion of the first spacer to expose top corners of the recess; and removing a portion of the substrate by using the mask layer, the first spacer and the second spacer as a mask, so as to form a first trench in the substrate in the periphery area and a second trench in the substrate in the array area, wherein the first spacer and the second spacer are formed from the same dielectric material.