Annealing-induced interfacial toughening using a molecular nanolayer

Area of Science:

• Materials Science
• Surface Chemistry
• Nanotechnology

Background:

• Self-assembled molecular nanolayers (MNLs) modify surface properties for diverse applications.
• Current MNLs have limited thermal stability (350-400°C), restricting high-temperature use.
• MNLs are explored for thin-film interfaces in molecular devices and passive layers.

Purpose of the Study:

• To investigate the use of MNLs at high temperatures to fortify copper-dielectric interfaces.
• To overcome the thermal stability limitations of MNLs for micro- and nano-electronic applications.
• To enhance the toughness of interfaces relevant to microelectronic wiring.

Main Methods:

• Annealing copper/MNL/SiO2 structures at 400-700°C.
• Characterizing interface toughness using mechanical testing.
• Analyzing fracture surfaces with electron spectroscopy and density functional theory (DFT) modeling.

Main Results:

• Annealed interfaces exhibited five times greater toughness than pristine structures, exceeding 20 J m⁻².
• High toughness was achieved without resorting to micrometer-thick layers.
• Thermal activation of interfacial siloxane bridging was identified as the toughening mechanism.

Conclusions:

• Molecular nanolayers can be effectively utilized at high processing temperatures, surpassing previous limitations.
• Thermally activated siloxane bridging strengthens MNL-inorganic interfaces, suppressing desorption.
• This approach enables molecular-level tailoring of interfacial properties for high-temperature and nanodevices.