High strength, low dielectric constant fluorinated silica xerogel films

The mechanical, electrical, and microstructural properties of low-k fluorin ated silica xerogels produced using a one step spin-on process are reported . Derived from a fluorinated silane monomer, these films are easily process ed and exhibit very low dielectric constants (2.1 as processed and 2.3 afte r heat treating at 450 degreesC in air). Structural determination by Fourie r transform infrared spectrophotometry indicates a fluorinated silica struc ture with shortened Si-O bonds; however, some of the fluorine is lost durin g annealing. Nanoindentation studies show high elastic moduli (12 GPa) and hardness (1 GPa). Microstructural analyses by transmission and scanning ele ctron microscopy indicate an unusual morphology with highly linked features and pore sizes in the 20-30 nm range. We believe the low dielectric consta nts and robust mechanical properties are due to the unusual microstructure of these films. (C) 2001 American Institute of Physics.