Planarization of a non-conformal device layer in semiconductor fabrication

Claim 1

In the fabrication of integrated circuits, a method for planarizing a non-conformal film comprising: providing a substrate, wherein the surface of the substrate includes narrow features separated by narrow spaces and wide features separated by wide spaces; depositing a non-conformal device layer over the surface of the substrate to fill the narrow and wide spaces, the non-conformal device layer having a thickness over the wide features that is greater than the thickness over the narrow features; depositing a conformal layer over the non-conformal layer, wherein the topography of the underlying non-conformal layer is reflected in the surface of the conformal layer; planarizing the conformal layer, using the non-conformal layer to serve as a stop layer, the planarizing producing a planar surface between the conformal layer and the non-conformal layer, wherein the non-conformal layer over the wide features is exposed; etching the non-conformal layer selective to the conformal layer, the etching substantially removing the non-conformal layer over the wide features except for small portions at the edges of the wide features protected by the conformal layer; etching to remove the conformal layer, the etching leaving the non-conformal layer remaining over the surface of the narrow features and small portions at the edge of the wide features; and polishing to produce a planar surface with the surface of the wide and narrow features, wherein the polish results in a substantially planar surface with reduced dishing in the wide spaces as a result of substantially removing the non-conformal layer over the wide features.