Planarization with reduced dishing
A method of forming a planarized layer on a substrate, where the substrate is cleaned, and the layer is formed having a surface with high portions and low portions. A resistive mask is formed over the low portions of the layer, but not over the high portions of the layer. The surface of the layer is etched, where the high portions of the layer are exposed to the etch, but the low portions of the layer underlying the resistive mask are not exposed to the etch. The etch of the surface of the layer is continued until the high portions of the layer are at substantially the same level as the low portions of the layer, thereby providing an initial planarization of the surface of the layer. The resistive mask is removed from the surface of the layer, and all of the surface of the layer is planarized to provide a planarized layer.
1. A method of forming a planarized layer on a substrate, the method comprising the steps of:
cleaning the substrate,
forming the layer having a surface with relatively high portions and relatively low portions,
forming a resistive mask over the relatively high portions of the layer and not over the relatively low portions of the layer,
treating the surface of the layer to make it more resistive to planarization, where the relatively low portions of the layer are exposed to the treatment and the relatively high portions of the layer underlying the resistive mask are not exposed to the treatment,
removing the resistive mask from the surface of the layer, and
planarizing the surface of the layer, where the relatively high portions of the layer are eroded at a first rate and the relatively low portions of the layer are eroded at a second rate that is less than the first rate due to the treatment received by the relatively low portions of the layer, to provide a planarized layer.
2. The method of claim 1 , wherein the step of treating the surface of the layer comprises implanting at least one of carbon, nitrogen, tantalum, tantalum nitride, titanium, and titanium nitride.
3. The method of claim 1 , wherein the step of treating the surface of the layer comprises plasma treatment with at least one of carbon, nitrogen, tantalum, tantalum nitride, titanium, and titanium nitride.
4. The method of claim 1 , wherein the layer is a copper layer.
5. The method of claim 1 , wherein the step of planarizing the surface comprises at least one of chemical mechanical polishing the surface and electropolishing the surface.