Enhanced Thermal Stability of Low-k Ethyl-Bridged Organosilicas Using Laser Spike Annealing

Incorporating organic bridges within porous organosilica films is a promising route to achieving required mechanical properties of ultralow-k dielectric films. To retain these critical organic bridges during thermal processing, submillisecond laser spike annealing (LSA) of sol–gel-derived, low-k, ethyl-bridged organosilica films was investigated. Structural and dielectric properties changes, as a function of the peak annealing temperature between 400 and ∼1400 °C, were determined by using a lateral-gradient LSA technique. Under LSA, the ethyl-bridged structures were found to remain stable to the highest LSA peak temperatures; in contrast, nearly 40% of the bridges were lost by 540 °C under hot plate annealing. Refining of Si–O–Si structures, and porosity generation from remnant porogens, was found to begin above ∼700 °C with densification only occurring ∼350 °C higher. This ability of LSA to retain organic bridges within a silica network during thermal processing may ultimately enable development of high-modulus, low-k films for advanced microelectronic applications.