Amine-terminated self-assembled monolayers are molecular nanolayers, typically formed via wet-chemical solution on specific substrates for precision surface engineering or interface modification. However, homogeneous assembling of a highly ordered monolayer by the facile, wet method is rather tricky because it involves process parameters, such as solvent type, molecular concentration, soaking time and temperature, and humidity level. Here, we select 3-aminopropyltrimethoxysilane (APTMS) as a model molecule of aminosilane for the silanization of nanoporous carbon-doped organosilicate (p-SiOCH) under tightly controlled process environments. Surface mean roughness (R a) and the water contact angle (θ) of the p-SiOCH layers upon silanization at a 10% humidity-controlled environment behave similarly and follow a three-stage evolution: a leap to a maximum at 15 min for R a (from 0.227 to 0.411 nm) and θ (from 25 to 86°), followed by a gradual decrease to 0.225 nm and 69o, finally leveling off at the above values (>60 min). The −NH3 + fraction indicating monolayer disorientation evolves in a similar fashion. The fully grown monolayer is highly oriented yielding an unprecedented low −NH3 + fraction of 0.08 (and 0.92 of upright −NH2 groups). However, while having a similar thickness of approximately 1.4 ± 0.1 nm, the molecular layers grown at 30% relative humidity exhibit a significantly elevated −NH3 + fraction of 0.42, indicating that controlling the humidity is vital to the fabrication of highly oriented APTMS molecular layers. A bonding-structure evolution model, as distinct from those offered previously, is proposed and discussed.

The downsizing of integrated circuits for the upcoming technology nodes has brought attention to sub-2 nm thin organic/inorganic materials as an alternative to metallic barrier/capping layers for nanoscaled Cu interconnects. While self-assembled monolayers (SAMs) serving as the barrier materials for copper metalized films are well studied, electromigration (EM) of Cu interconnects encapsulated by SAMs is an untouched research topic. In this study, we report an all-wet encapsulating process involving SAM seeding/encapsulating and electroless narrow-gap filling to fabricate nanoscaled copper interconnects that are completely encapsulated by a 1 nm-thin amino-based SAM, subsequently annealed to some extents prior to EM testing. Both annealing and SAM encapsulation retard EM of the Cu interconnects tested at current densities on orders of 108–109 A cm−2. Particularly, SAM encapsulation quintuples the lifetime of, for example, as-fabricated Cu interconnects from 470 to 2,890 s. Electromigration failure mechanisms are elucidated from analyses of activation energies and current-density scale factors obtained from the accelerated EM testing. The importance of SAM qualities (e.g., ordering and layered structure) as a prerequisite for the reliability enhancement cannot be overestimated, and the results of the SAM quality evaluation are presented. The mechanism of reliability enhancement is also thoroughly discussed.

No abstract