Pedestals for modulating film properties in atomic layer deposition (ALD) substrate processing chambers

A system to deposit a film on a substrate using atomic layer deposition includes a pedestal arranged in a processing chamber to support the substrate on a top surface of the pedestal when depositing the film on the substrate. A first annular recess in the pedestal extends downwardly from the top surface of the pedestal and radially inwardly from an outer edge of the pedestal towards an outer edge of the substrate. The first annular recess has an inner diameter that is greater than a diameter of the substrate. An annular ring is made of a dielectric material and is arranged around the substrate in the first annular recess. A second annular recess in the pedestal is located under the annular ring. The second annular recess has a height and extends radially inwardly from the outer edge of the pedestal towards the outer edge of the substrate.