Structural models and barrier properties of amine-terminated trialkoxysilane monolayers incubated in nonpolar vs. polar protic solvents

Characterizing the Ligand Shell Morphology of PEG-Coated ZnO Nanocrystals Using FRET Spectroscopy

“…48,60 Since trialkoxysilanes are well-known self-assembled monolayer (SAM) molecules, we expect to form a siloxane monolayer on the surface of ZnO NCs. 65,66 We also note that C−O−C stretching in the ethylene glycol unit will also appear approximately at the same region of the IR spectrum. The pronounced shoulder at 1135 cm −1 for all PEG-coated ZnO NCs may be attributed to the C−O−C stretching.…”

“…Ligand-specific peaks at 1350 and 1245 cm –1 can be assigned to ethylene glycol –CH 2 wagging and twisting modes, respectively . The peak at approximately 1100 cm –1 can be assigned to Si–O–Si asymmetrical stretching, indicating the presence of a siloxane layer. − The peak at approximately 855 cm –1 can be assigned to Zn–O–Si stretching, which is a strong indication of silane capping along with the presence of different –CH 2 stretching modes. , Since trialkoxysilanes are well-known self-assembled monolayer (SAM) molecules, we expect to form a siloxane monolayer on the surface of ZnO NCs. , We also note that C–O–C stretching in the ethylene glycol unit will also appear approximately at the same region of the IR spectrum. The pronounced shoulder at 1135 cm –1 for all PEG-coated ZnO NCs may be attributed to the C–O–C stretching .…”

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

“…35,36 Our previous study has shown that the adhesion strength of as-deposited Cu films on an APTMS-SAM on SiO 2 is significantly higher than that of unpassivated Cu films on SiO 2 , 6.1 vs 27.6 MPa; the adhesion strength of the SAM-passivated Cu films after annealing is markedly increased from 27.6 to 72.6 MPa. 37 The extraordinarily high adhesion strength, along with the high barrier capability of the orderly SAM, should be highly effective in retarding copper diffusion through surface and interface, which thus are unlikely to be the dominant mechanisms for the failure of the SAM-encapsulated Cu interconnects. Indeed, the high activation energy of 0.93 eV for the SAM-fully-passivated Cu interconnects suggests that their failure is primarily through EMinduced diffusion of Cu via either grain boundaries or grains.…”

“…49 The involvements of various competing functional moieties, such as hydrolysable methoxysilane (Si-OCH 3 ) head groups, substrate silanol groups and hydrolysis species of the APTMS molecules in an incubation solution, readily cause the formation of disordered molecular layers 50 or multilayers. 51 Solvent type in terms of polarity difference is also critical to structural arrangements, 52 surface morphologies 53 or barrier/pore-sealing capabilities 37,54 of the synthesized self-assembled molecular layers. It should be noted that using polar incubation media (e.g., ethanol) accelerates oligomer formation in situ in the incubation solution, and could lead to the synthesis of poorly arranged amino-based molecular layers that have no barrier and adhesive capabilities; 37 poorly arranged amino-terminated SAMs also render electrolessplated overlayers to yield a very low adhesion strength of 3.1 MPa.…”

“…51 Solvent type in terms of polarity difference is also critical to structural arrangements, 52 surface morphologies 53 or barrier/pore-sealing capabilities 37,54 of the synthesized self-assembled molecular layers. It should be noted that using polar incubation media (e.g., ethanol) accelerates oligomer formation in situ in the incubation solution, and could lead to the synthesis of poorly arranged amino-based molecular layers that have no barrier and adhesive capabilities; 37 poorly arranged amino-terminated SAMs also render electrolessplated overlayers to yield a very low adhesion strength of 3.1 MPa. 55 Here, the APTMS molecular layer is fabricated based on our recent findings by using strictly controlled processing parameters, a low humidity environment, 20 and nonpolar solvent (toluene) as an incubation medium.…”