Patent ID: 6858153

Claim:
A dual damascene process for depositing intermetal dielectric layers, comprising: depositing a first dielectric layer having a dielectric constant less than about 4 by oxidizing a first organosilicon compound comprising oxygen; depositing a second dielectric layer having a dielectric constant less than about 4 on the first dielectric layer by oxidizing a second organosilicon compound comprising oxygen; depositing a third dielectric layer having a dielectric constant less than about 4 on second dielectric layer by oxidizing a third organosilicon compound comprising oxygen; etching the first and second dielectric layers to form vertical interconnects; and etching the third dielectric layer to form horizontal interconnects wherein one or more process conditions for etching the third dielectric layer is varied to provide the third dielectric layer an etch rate that is at least about three times greater than an etch rate for the second dielectric layer.