Patent ID: 6410442
Filing Date: 2002-06-25
Classification: C23F,H01L

Abstract:
A method for mask-less differential etching/planarizing a recess-patterned surface of a layer of copper or copper alloy, which method comprises the sequential steps of:(a) providing a workpiece having upper and lower opposed major surfaces, the upper major surface comprising a layer of copper or copper alloy and including a recessed area and a non-recessed area; (b) securing the lower major surface of said workpiece to a facing surface of a movable workpiece holder for providing movement of the workpiece in a direction parallel to said upper surface; (c) providing a source of a liquid etchant solution, said etchant solution comprising: i. at least one copper or copper alloy etchant; ii. a surfactant in an amount sufficient for providing wetting of the copper or copper alloy surface by the etchant solution; iii. an additive in an amount sufficient for increasing the viscosity of the etchant solution to a level greater than that of the solvent; and iv. a liquid solvent; (d) directing etchant solution form said source onto said upper surface of said workpiece while moving the workpiece in a direction parallel to said upper surface, thereby at least partially filling the recessed area with etchant solution and distributing said etchant solution as a film covering the non-recessed area, said film of etchant solution being replenished with fresh etchant solution from said source at a faster rate than the etchant solution filling the recessed area; whereby the rate of etching of the copper or copper alloy within the recessed area is slower than that of the non-recessed area, resulting in differential etching of the recess-patterned surface of the layer of copper or copper alloy; and (e) continuing the differential etching of step (d) for a time sufficient to reduce the thickness of the non-recessed area of the copper or copper alloy layer, thereby at least partially planarizing said upper surface.