Patent ID: 7244680
Filing Date: 2007-07-17
Classification: H01L

Abstract:
1. A method for forming shallow wench isolation structures, the method comprising: forming a mask upon a substrate having a cell region and a periphery region; so as to cover at least a portion of the cell region and at least a portion of the periphery region; forming a patterned photoresist layer upon the mask, the photoresist layer exposing a portion of the mask in the cell region and exposing a portion of the mask in the periphery region; performing a first etching process to remove substantially all of the mask layer exposed by the photoresist layer in the periphery region and to remove a portion of the mask layer exposed by the photoresist layer in the cell region; performing a second etching process to partially form a trench having rounded corners in the periphery region and to remove more of the mask layer in the cell region; performing a third etching process to deepen the trench formed in the periphery region while maintaining the rounded corners thereof and to form a trench in the cell region; and filling the trench in the periphery region and filling the trench in the cell region with an insulating material.