Journal of Vacuum Science & Technology A, Vol.15, No.6, 3005-3014, 1997
Surface Processes Occurring on TiSi2 and CoSi2 in Fluorine-Based Plasmas - Reactive Ion Etching in CF4/Chf3 Plasmas
The kinetics of TiSi2 and CoSi2 etching in CF4/CHF3 plasmas are studied. X-ray photoelectron spectroscope studies show that after the reactive ion etching (RIE) etching of TiSi2 and CoSi2 with different gas composition, complex protective films, containing both CFx polymers and metal fluorides, are formed. The relative amount of metal fluoride and polymer depends on the gas composition. A phenomenological model describing the RIE of the metal silicides in the carbon-fluoride plasmas is established. It is shown that in the case of TiSi2, selective etching of SiO2 can be obtained by increasing the polymer precursor radical concentration in the plasma. Effective ways for the removal of the post-dry-etch residues from the TiSi2 and CoSi2 surfaces have been developed. It is shown that the use of a complex cleaning procedure, including both the SPM (H2SO4:H2O2=4:1) and O-2-plasma treatments, provides practically clean surfaces of both the Ti and Co silicides without the metal fluorides and polymers.