Patent ID: 7326625

Claim:
A method of forming a trench structure comprising: forming a deep trench having a first width and a first depth on a substrate, wherein forming the deep trench comprises: forming a pad oxide layer pattern on the substrate; forming a first nitride layer pattern on the pad oxide layer pattern; forming a first oxide layer pattern on the first nitride layer pattern; partially etching the substrate using the first oxide layer pattern, the first nitride layer pattern and the pad oxide layer pattern as etching masks; and removing the first oxide layer pattern; forming an enclosed void in the deep trench by filling the deep trench with a first insulation layer pattern in a manner that defines the enclosed void in the deep trench, wherein forming the enclosed void in the deep trench comprises: forming a second oxide layer pattern on a sidewall of the deep trench; forming a second nitride layer pattern on the second oxide layer pattern to form an opening in the deep trench; and forming a third oxide layer pattern on the second nitride layer pattern to complete the enclosed void by covering a top portion of the opening; forming a shallow trench on the deep trench, the shallow trench having a second width substantially wider than the first width and a second depth substantially shallower than the first depth; and filling up the shallow trench with a second insulation layer pattern.