Properties of fluorinated silicon oxide films formed using fluorotriethoxysilane for interlayer dielectrics in multilevel interconnections

Properties of a fluorinated silicon oxide (SiOF) film for interlayer dielectrics in multilevel interconnections of ultralarge-scale integrated circuits (ULSIs) are investigated. The SiOF films are formed by a room temperature chemical vapor deposition (RTCVD) technique using fluorotriethoxysilane [FSi(OC₂H₅)₃, FTES] and pure water as gas sources. The SiOF film property changes by annealing at 400 or 900°C are studied. Although the Si-O bond absorption peak position in the Fourier transform infrared (FTIR) spectrum is not changed by 400°C annealing, the peak position for the 900°C annealed SiOF films shifts to low wave numbers. The full width at half-maximum (FWHM) of the Si-O bond absorption peak increases by 400°C annealing, and it further increases by 900°C annealing. The tendency of the Si-F bond peak absorption coefficient change is inverse to the change of FWHM, indicating that fluorine influences the Si-O bond nature. Other properties such as the fluorine atomic concentration, refractive index, etching rate, shrinkage, residual stress, and leakage current density are changed by the annealing. These property changes are due to changes in the chemical bonding structure. No crack is observed for the SiOF films formed on aluminum wiring patterns after 400°C annealing.