Chemical-Structure Evolution Model for the Self-Assembling of Amine-Terminated Monolayers on Nanoporous Carbon-Doped Organosilicate in Tightly Controlled Environments

Abstract

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.

Self-assembly of amino-terminated monolayers depending on the chemical structure

“…4,5 Amino-terminated SAMs prepared from commercially available silanes such as 3-aminopropyl-triethoxysilane (APTES) and 3-aminopropyl-trimethoxysilane (APTMS) are mostly used to promote the biofunctionalization of a solid support in bioanalytical platforms, 6 to study protein or cell adhesion, 7 and to functionalize (nano)particles. 8–10 The formation of an aminosilane layer is sensitive to the reaction conditions, and the quality of the APTES or APTMS films depends on different parameters such as concentration, 11 the nature of the solvent, 12 time, 13 temperature, 14 humidity level, 15 and post-deposition treatment (the annealing step). 16,17 Many experimental conditions were described to deposit aminosilane films by wet chemistry, giving rise to monolayer 18,19 or multilayer 20 films.…”

(3-Aminopropyl)trimethoxysilane Self-Assembled Monolayer as Barrier of Porous SiOCH for Electroless Cu Metallization: Optimizations of SiOCH Hydroxylation and Monolayer Functionalization

“…13 Before the functionalization, a full set of high-resolution XPS was used to ensure the highlyoriented APTMS-SAM for the optimized silanization samples. 32 The APTMS-coated samples were then subjected to a functionalization by SC-1 solution creating seed-adsorbing groups for the Ni seeding before the electroless deposition of Cu. (The capacity of this APTMS-SAM after various degrees of SC-1 functionalization as a barrier for Cu metallization will be discussed later.)…”

Enhancement of Electromigration Reliability of Electroless-Plated Nanoscaled Copper Interconnects by Complete Encapsulation of a 1 nm-Thin Self-Assembled Monolayer

“…1 were followed to fabricate two different types of Cu interconnects, namely SAMcompletely-encapsulated and unpassivated Cu lines. First, some test pieces were tethered with an orderly APTMS-SAM in anhydrous toluene under the precisely controlled process parameters recently reported, 20 followed by functionalization in an SC-1 solution. The SAM-functionalized samples were then processed by seeding, electroless-Cu plating/polishing and APTMS-SAM capping (see Ref.…”