an inter - level insulator structure is provided having an effective insulator dielectric constant approaching 1 . an embodiment of the inter - level insulator comprises a first metal layer comprising a first plurality of metal lines ; a second metal layer comprising a second plurality of metal lines , and at least one via connected to the first metal layer ; and an air gap interposed between the first metal layer and the second metal layer . in one embodiment , the air gap is also present between metal lines on either metal layer , such that air gaps act as intra - level as well as inter - level insulators . a method is also provided to deposit and pattern a sacrificial polymer , and form metal layers . the sacrificial polymer is capable of being decomposed to become air gaps during annealing .