Plating method and apparatus for controlling deposition on predetermined portions of a workpiece
View Patent ↗The present invention relates to methods and apparatus for plating a conductive material on a workpiece surface in a highly desirable manner. Using a workpiece-surface-influencing device, such as a mask or sweeper, that preferentially contacts the top surface of the workpiece, relative movement between the workpiece and the workpiece-surface-influencing device is established so that an additive in the electrolyte solution disposed on the workpiece and which is adsorbed onto the top surface is removed or otherwise its amount or concentration changed with respect to the additive on the cavity surface of the workpiece. Plating of the conductive material can place prior to, during and after usage of the workpiece-surface-influencing device, particularly after the workpiece surface influencing device no longer contacts any portion of the top surface of the workpiece, to achieve desirable semiconductor structures.
1. A method of electroplating a conductive top surface of a workpiece, the conductive top surface of the workpiece including a top portion and a cavity portion, the conductive top surface defined by a seed layer, the method comprising:
applying, over the conductive top surface of the workpiece, an electrolyte solution with at least one additive disposed therein, a first portion of the additive becoming adsorbed on the top portion and a second portion of the additive becoming adsorbed on the cavity portion;
using a workpiece-surface-influencing device to make physical contact with the top portion and establishing relative movement with the workpiece to change at least the first portion of the additive adsorbed onto the seed layer of the top portion;
after making physical contact, moving the workpiece-surface-influencing device away from the workpiece surface so that the physical contact between the workpiece-surface-influencing device and the workpiece no longer occurs;
after moving the workpiece-surface-influencing device away from the workpiece surface, electroplating the conductive top surface of the workpiece with a conductor obtained from the electrolyte solution at least during a period of time when at least some of the change is maintained and while the workpiece-surface-influencing device remains moved away from the workpiece surface, thereby causing greater electroplating over the seed layer of the cavity portion relative to the electroplating over the seed layer of the top portion, wherein the electroplating results in overfill of the conductor electroplated over the cavity portion relative to the conductor electroplated over the top portion; and
after electroplating, removing a portion of the conductor from over the top portion of the workpiece surface and a first portion of the conductor from over the cavity portion, wherein after removal a second portion of the conductor remains over the cavity portion.
2. The method of claim 1 , wherein removing the portion of the conductor over the top portion comprises removing substantially all of the conductor over the top portion.
3. The method of claim 1 , wherein removing comprises chemical mechanical polishing.
4. The method of claim 1 , wherein removing comprises electroetching.
5. The method of claim 1 , wherein removing comprises etching.
6. The method of claim 1 , wherein the conductive top surface further includes a plurality of small cavity portions, wherein the plurality of small cavity portions have widths that are smaller than the width of the cavity portion, wherein the electroplating results in an overfill of the conductor being plated over the plurality of small cavity portions.
7. The method of claim 6 , wherein the electroplating results in the overfill of the conductor being plated over the plurality of small cavity portions is relative to the conductor electroplated over the top portion.
8. The method of claim 1 , further comprising annealing the workpiece before removing the portion of the conductor from over the top portion of the workpiece surface and the first portion of the conductor from over the cavity portion.
9. The method of claim 8 , wherein, after annealing, a grain size of the conductor over the cavity portion is greater than a grain size of the conductor over the top portion.
10. The method of claim 1 , wherein the at least one additive comprises an accelerator.
11. The method of claim 1 , wherein the electroplating comprises applying a voltage between the workpiece and an electrode.