Characterization of fluorinated silicon dioxide films by nuclear reaction analysis and optical techniques

Abstract

Fluorinated silicon dioxide films have been characterized using nuclear reaction analysis (NRA) and optical techniques. The use of prompt gamma-ray emitting nuclear reaction for measuring the concentration profiles of fluorine in thin films (>200 Å) of SiO2:F is discussed. Films of SiO2:F were studied using the 19F(p,αγ)16O reaction at 340 keV resonance, by observing the emitted gamma rays in a 3 inch×3 inch BGO detector. The film thickness, fluorine distributions and fluorine concentrations were determined from the NRA data. Film thickness was also determined from spectroscopic ellipsometery measurement and fluorine concentrations were also obtained from Fourier transform infrared spectroscopy (FTIR) data. For NRA analysis, the system has been calibrated using several ion implanted fluorine standards and well known fluorine compounds. This technique is now intrinsically capable of determining the fluorine content of any sample with a sensitivity of 100 ppm (atomic) without the use of reference standard samples. FTIR and NRA techniques are shown as a useful combination to study the changes in structure of SiO2:F films.