Novel Precursor for Development of Si–C2H4–Si Networks in SiCH for Application as a Low-k Cap Layer beyond 22 nm Nodes

SiCH films are a potentially very useful low-k cap layer for covering Cu trenches in ultralarge-scale integration (ULSI) devices. To induce Si–C2H4–Si networks in SiCH film structures, 1,1-divinyl silacyclopentane (DVScP) and 5-silaspiro-[4,4]-nonane (SSN) were designed and prepared. Isobutyl trimethyl silane (iBTMS) and diisobutyl dimethyl silane (DiBDMS) were also designed to form Si–CH2–Si networks in the SiCH molecular structure. SiCH films were formed by plasma-enhanced chemical vapor deposition (PECVD), for use as a low-k cap layer and a Cu diffusion barrier on top of the Cu trenches. We demonstrated additional Si–C2H4–Si networks that can effectively suppress Cu diffusion in SiCH low-k barrier films with a reduced k-value of 3.1.