Patent ID: 7723226

Claim:
A method for fabricating a bilayer porous low-k dielectric, the method comprising: forming on a surface of a substrate a first dielectric layer having a first porogen content; forming on the first dielectric layer a second dielectric layer having a second porogen content, the second porogen content being greater than the first porogen content; subjecting the first and the second dielectric layers to a first curing process wherein substantially all porogen is removed from the first dielectric layer thereby forming a first porous matrix within the first dielectric layer, and wherein some, but not substantially all porogen is removed from the second dielectric layer; forming atop the second dielectric layer a third dielectric layer; and subjecting the first, the second, and the third dielectric layers to a second curing process, wherein substantially all porogen is removed from the second dielectric layer during the second curing process thereby forming a second porous matrix within the second dielectric layer.