US Patent 7393779 Shrinking contact apertures through LPD oxide

Sublithographic contact apertures through a dielectric are formed in a stack of dielectric, hardmask and oxide-containing seed layer. An initial aperture through the seed layer receives a deposition of oxide by liquid phase deposition, which adheres selectively to the exposed vertical walls of the aperture in the seed layer. The sublithographic aperture, reduced in size by the thickness of the added material, defines a reduced aperture in the hardmask. The reduced hardmask then defines the sublithographic aperture through the dielectric.