Semiconductor device having air gap and method for manufacturing the same

A method for manufacturing a semiconductor device having an air gap, comprising:

• providing a substrate having a first dielectric layer and a second dielectric layer formed thereon successively;
• forming a mask layer on the second dielectric layer;
• patterning the first dielectric layer and the second dielectric layer by using the mask layer as a mask so as to form a plurality of grooves;
• filling a conducting material into the grooves;
• removing redundant conducting material on the second dielectric layer until the second dielectric layer is exposed so as to form a plurality of conductive trenches;
• forming a molecular sieve on the second dielectric layer and the conductive trenches;
• forming a hard mask layer on the molecular sieve, wherein the hard mask layer comprises a groove through the hard mask layer and positioned between at least one pair of adjacent conductive trenches;
• and
• removing a portion of the second dielectric layer by flowing a reactant gas towards the second dielectric layer through a portion of the molecular sieve corresponding to the groove of the hard mask layer, to form an air gap between the at least one pair of adjacent conductive trenches.