Roughness reduction methods for materials using illuminated etch solutions

A method of processing a substrate for a microelectronic workpiece, comprising:

• receiving a substrate for a microelectronic workpiece having a polycrystalline elemental metal to be etched from a surface of the substrate;
• applying a liquid etch solution comprising hydrogen peroxide to the surface of the substrate, the liquid etch solution having a first level of reactants with respect to the polycrystalline elemental metal;
• illuminating the liquid etch solution to cause formation of hydroxyl radicals from the hydrogen peroxide, the formation of hydroxyl radicals at least in part causing the liquid etch solution to have a second level of reactants with respect to the polycrystalline elemental metal, the second level of reactants being greater than the first level of reactants;
• oxidizing the polycrystalline elemental, metal with the liquid etch solution to form an oxidized metal;
• and
• removing the oxidized metal by dissolving, wherein the oxidizing having an oxidation rate constant greater than a dissolution rate constant for the dissolving.

A method to polish a surface of a material, comprising:

• receiving a polycrystalline elemental metal material to be polished;
• applying an etch solution to a surface of the polycrystalline elemental metal material, the etch solution having a first level of reactants with respect to the polycrystalline elemental metal material;
• exposing the etch solution and the surface of the polycrystalline elemental metal material to illumination to form an oxidized layer of material on the surface of the polycrystalline elemental metal material, the exposing causing the etch solution to have a second level of reactants with respect to the polycrystalline elemental metal material that is greater than the first level;
• and
• removing the modified oxidized layer of material by dissolving to cause the polycrystalline elemental metal material to have a polished surface, the polished surface having less surface variation than the surface of the polycrystalline elemental metal material before the exposing and removing, wherein the oxidizing having an oxidation rate constant greater than a dissolution rate constant for the dissolving.