US Patent 10049869 Composite dielectric interface layers for interconnect structures

Dielectric composite films characterized by a dielectric constant (k) of less than about 7 and having a density of at least about 2.5 g/cm3 are deposited on partially fabricated semiconductor devices to serve as etch stop layers. The composite films in one embodiment include at least two elements selected from the group consisting of Al, Si, and Ge, and at least one element selected from the group consisting of O, N, and C. In one embodiment the composite film includes Al, Si and O. In one implementation, a substrate containing an exposed dielectric layer (e.g., a ULK dielectric) and an exposed metal layer is contacted with an aluminum-containing compound (such as trimethylaluminum) and, sequentially, with a silicon-containing compound. Adsorbed compounds are then treated with an oxygen-containing plasma (e.g., plasma formed in a CO2-containing gas) to form a film that contains Al, Si, and O.