A method of forming an interconnection structure is disclosed, including providing a substrate, forming a patterned layer on the substrate, the patterned layer comprising at least a trench formed therein, depositing a first dielectric layer on the patterned layer and sealing an air gap in the trench, depositing a second dielectric layer on the first dielectric layer and completely covering the patterned layer, and performing a curing process to the first dielectric layer and the second dielectric layer.