Study on Fluorine Incorporation during Etch Step for HDP-CVD Oxide Gap-Filling of Nano-Scale Shallow-Trench Isolation

For gap-filling of nano-scale shallow trench isolation (STI) with no voids in high-density plasma chemical vapor deposition (HDP-CVD), an etch gas containing NF3 in the continuous deposition/etch or cyclic deposition-etch-deposition (DED) processes has been adopted and in turn its use has led to uorine incorporation. Since F incorporation observed during the gap-fill process is known to affect the post-process after gap-fill, a control and an understanding of fluorine incorporation in the etch step is required. Fluorine incorporation in the HDP-CVD oxide was investigated by varying the NF3/O2 and the NF3/Ar plasma conditions during the etch step in the reactive ion etching (RIE) and the chemical dry etching (CDE) modes. As the flow ratio of NF3 gas was increased, the fluorine incorporation increased. As a result of the increased F incorporation with increasing NF3 flow ratio, wet etch rates of plasma-etched HDP oxides increased. For gap-filling of nano-scale shallow trench isolation (STI) with no voids in high-density plasma chemical vapor deposition (HDP-CVD), an etch gas containing NF3 in the continuous deposition/etch or cyclic deposition-etch-deposition (DED) processes has been adopted and in turn its use has led to uorine incorporation. Since F incorporation observed during the gap-fill process is known to affect the post-process after gap-fill, a control and an understanding of fluorine incorporation in the etch step is required. Fluorine incorporation in the HDP-CVD oxide was investigated by varying the NF3/O2 and the NF3/Ar plasma conditions during the etch step in the reactive ion etching (RIE) and the chemical dry etching (CDE) modes. As the flow ratio of NF3 gas was increased, the fluorine incorporation increased. As a result of the increased F incorporation with increasing NF3 flow ratio, wet etch rates of plasma-etched HDP oxides increased. KCI Citation Count: 2