Patent ID: 8399350
Filing Date: 2013-03-19
Classification: H01L

Abstract:
1. A method of fabricating a microelectronic element having an air gap in a dielectric layer thereof, comprising: a) forming a cap layer having a first portion overlying surfaces of metal lines and a second portion overlying a surface of a dielectric layer in which the metal lines are disposed, the first portion having a first height above the surface of the dielectric layer, and the second portion having a second height above the surface of the dielectric layer, the second height being greater than the first height; b) after step (a), forming a mask over the cap layer, the mask having a multiplicity of randomly disposed holes, each exposing a surface of only the second portion of the cap layer, the mask fully covering a surface of the first portion of the cap layer; and c) after step (b), directing an etchant towards the first and second portions of the cap layer to form holes in the cap layer aligned with the holes in the mask, and to remove material from the dielectric layer where exposed to the etchant by the holes in the cap layer, wherein the mask protects the first portion of the cap layer from being attacked by the etchant.