Suppression of chemical and electrical instabilities in mesoporous silica films by molecular capping

Mesoporous silica (MPS) thin films are attractive for achieving low relative dielectric permittivity (low k) interlayer isolation in integrated circuit wiring, but are susceptible to instabilities in electrical behavior due to water uptake and copper diffusion. Here, we show that capping MPS films with a trimethyl-group terminated organosilane layer irreversibly suppresses moisture-induced capacitance instabilities, and decreases the relative dielectric permittivity and Cu-induced leakage currents. Analysis of capacitance-voltage and current-voltage characteristics along with infrared spectroscopy shows that the trimethyl organosilanes inhibit hydrogen bonding of water molecules by rendering the dielectric surfaces hydrophobic. These features are promising for tailoring the chemical and interfacial properties and reliability of porous dielectric materials for insulation in device wiring applications. (c) 2006 American Institute of Physics.