Spin-on dielectric stack low-k integration with EB curing technology for 45nm-node and beyond

To achieve effective k value less than 3.0, we investigated spin-on dielectric stack damascene integration scheme with electron beam (EM) cure. By using porous-MSQ (k=2.3) as ILD and dense-MSQ (k=2.9) as hard mask (HM), effective k value could be lowered, and by EB curing the full dielectric stack only once, mechanical strength for both ILD and HM were improved and a reduced thermal budget was obtained. In addition, a low damage resist strip process for the low-k materials was evaluated. These elements of BEOL technology have applicability to 45nm technology node and beyond.