A high quality thin dielectric layer is achieved by annealing a substrate and base oxide layer at a first temperature in a first ambient and subsequently annealing the substrate and base oxide layer at a second temperature in a second ambient, the base oxide layer overlying a top surface of the substrate. Prior to the first anneal, the base oxide layer has an initial thickness and density. The first anneal causes a first density and thickness change in the base oxide layer from the initial thickness and density to a first thickness and density, with no incorporation of a component of the ambient within the base oxide layer. The first thickness is less than the initial thickness and the first density is greater than the initial density. The second anneal causes a second density and thickness change in the base oxide layer from the first thickness and density to a second thickness and density. The second thickness is larger than the first thickness and the second density is on the order of the greater than or equal to the first density.