Deposition of amorphous silicon dioxide from molecular complexes by a photoresist free process

Silicon coordination compounds of the general formula Si(O2CCH3)2(RCOCH2COR)2 (R = methyl, tert-butyl), were studied as precursors for the photochemical deposition of amorphous thin films of SiO2. Solutions of the inorganic complexes were spin coated on p-type silicon (1 0 0) substrates and photolyzed at room temperature using a 254 nm UV light. The acetylacetonate derivatives underwent a photochemical reaction [quantum yield (Φ) ∼ 0.01], resulting in the formation of amorphous SiO2 thin films. Auger electron spectroscopy indicated that the final film is carbon-free SiO2 while FTIR spectroscopy indicated the film has characteristics of silica glass rather than silica gel. Thin films prepared with the precursor complexes were photolyzed through a lithography mask, followed by rinsing with a chloroform/petroleum ether mixture, to yielding 2 μm feature patterned lines of SiO2 without need for a photoresist/etching process.