Image Number 2 for United States Patent #7482278.
A new method of depositing PE-oxide or PE-TEOS. An HDP-oxide is provided over a pattern of polysilicon. An etch back is performed to the deposited HDP-oxide, a layer of plasma-enhanced SiN is deposited. This PE-SiN is etched back leaving SiN spacers on the sidewalls of the poly pattern, further leaving a deposition of HDP-oxide on the top surface of the poly pattern. The profile of the holes within the poly pattern in such that the final layer of PE-oxide or PE-TEOS is deposited without resulting in the formation of keyholes in this latter layer.