Plasma-initiated chemical vapour deposition of organosiloxane thin films: From the growth mechanisms to ultrathin low-kpolymer insulating layers

The growth mechanisms of low dielectric constant polymer thin films elaborated from the atmospheric-pressure plasma-initiated chemical vapour deposition (AP-PiCVD) reaction of a cyclic vinyl organosiloxane are experimentally elucidated in this study. The use of ultrashort plasma pulses (ca. 100 ns), as a polymerisation initiator, with long plasma off-times results in the formation of atomically smooth thin films. The increase of the monomer saturation ratio,P-M/P-sat, results in an increase in the growth rate and a better retention of the cyclic structure of the monomer, promoting lower dielectric constants. Based on this experimental study, guidelines are provided to determine the optimal process window for the AP-PiCVD of functional polymer thin films.