Dielectric and mechanical properties of surface modified organosilicate films

Low dielectric constant organosilicate films have been successfully synthesized by sol-gel approach using tetraethyl orthosilicate (TEOS) and methyltriethoxysilane (MTES) as precursors with acid and base as catalysts. Several surface modifications are employed to remove residual silanol groups and increase hydrophobicity of the films so as to resist moisture attack from atmosphere and improve dielectric properties of the films. The porosity, dielectric and mechanical properties of the organosilicate films are measured as a function of MTES fraction and it is found that these properties can be controlled effectively and easily by acid/base two-step catalysis having different mechanisms of hydrolysis and condensation. Higher fraction of MTES leads to higher porosity and lower dielectric constant of the films, but deteriorates elastic modulus and hardness of the films.