Surface-Localized Sealing of Porous Ultralow-k Dielectric Films with Ultrathin (&lt;2 nm) Polymer Coating

5 years ago

Surface-Localized Sealing of Porous Ultralow-k Dielectric Films with Ultrathin (<2 nm) Polymer Coating

Alexander Yoon, Taewook Nam, Seong Jun Yoon, Sung Gap Im, Hyungjun Kim, Kwanyong Pak, Byung Jin Cho

Semiconductor integrated circuit chip industries have been striving to introduce porous ultralow-k (ULK) dielectrics into the multilevel interconnection process in order to improve their chip operation speed by reducing capacitance along the signal path. To date, however, highly porous ULK dielectrics (porosity >40%, dielectric constant (k) <2.4) have not been successfully adopted in real devices because the porous nature causes many serious problems, including noncontinuous barrier deposition, penetration of the barrier metal, and reliability issues. Here, a method that allows porous ULK dielectrics to be successfully used with a multilevel interconnection scheme is presented. The surface of the porous ULK dielectric film (k = 2.0, porosity ∼47%) could be completely sealed by a thin (<2 nm) polymer deposited by a multistep initiated chemical vapor deposition (iCVD) process. Using the iCVD process, a thin pore-sealing layer was localized only to the surface of the porous ULK dielectric film, which could minimize the increase of k; the final effective k was less than 2.2, and the penetration of metal barrier precursors into the dielectric film was completely blocked. The pore-sealed ULK dielectric film also exhibited excellent long-term reliability comparable to a dense low-k dielectric film.

Publisher URL: http://dx.doi.org/10.1021/acsnano.7b01998

DOI: 10.1021/acsnano.7b01998