| 摘要 |
A method is provided for fabricating a microelectronic element having an air gap in a dielectric layer thereof. A dielectric cap layer can be formed which has a first portion overlying surfaces of metal lines, the first portion extending a first height above a height of a surface of the dielectric layer and a second portion overlying the dielectric layer surface and extending a second height above the height of the surface of the dielectric layer, the second height being greater than the first height. After forming the cap layer, a mask can be formed over the cap layer. The mask can have a multiplicity of randomly disposed holes. Each hole may expose a surface of only the second portion of the cap layer which has the greater height. The mask may fully cover a surface of the first portion of the cap layer having the lower height. Subsequently, an etchant can be directed towards the first and second portions of the cap layer to form holes in the cap layer aligned with the holes in the mask. Material can be removed from the dielectric layer where exposed to the etchant by the holes in the cap layer. At such time, the mask can protect the first portion of the cap layer and the metal lines from being attacked by the etchant.
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