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 .