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 CF_x 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 O₂–plasma treatments, provides practically clean surfaces of both the Ti and Co silicides without the metal fluorides and polymers. © 1997 American Vacuum Society.