Sidewalls of electroplated copper interconnects
A method including depositing an alloying layer along a sidewall of an opening and in direct contact with a seed layer, the alloying layer includes a crystalline structure that cannot serve as a seed for plating a conductive material, exposing the opening to an electroplating solution including the conductive material, the conductive material is not present in the alloying layer, applying an electrical potential to a cathode causing the conductive material to deposit from the electroplating solution onto the cathode exposed at the bottom of the opening and causing the opening to fill with the conductive material, the cathode includes an exposed portion of the seed layer and excludes the alloying layer, and forming a first intermetallic compound along an intersection between the alloying layer and the conductive material, the first intermetallic compound is formed as a precipitate within a solid solution of the alloying layer and the conductive material.
1. A method of plating a structure comprising an opening etched in a nonmetallic material and a diffusion barrier deposited along a sidewall and along a bottom of the opening, the method comprising:
depositing a seed layer along the sidewall and the bottom of the opening in direct contact with the diffusion barrier, wherein the seed layer comprises a crystalline structure suitable for plating copper;
depositing an alloying layer along the sidewall of the opening and in direct contact with the seed layer and parallel to the sidewall of the opening, wherein the alloying layer comprises a crystalline structure that cannot serve as a seed for plating a conductive material;
exposing the opening to an electroplating solution comprising the conductive material wherein the conductive material is not present in the alloying layer;
applying an electrical potential to a cathode causing the conductive material to deposit from the electroplating solution onto the cathode exposed at the bottom of the opening and causing the opening to fill with the conductive material, wherein the cathode comprises an exposed portion of the seed layer and excludes the alloying layer; and
forming a first intermetallic compound along an intersection between the alloying layer and the conductive material, the first intermetallic compound is formed as a precipitate within a solid solution of the alloying layer and the conductive material.
2. The method of claim 1 , further comprising:
forming a second intermetallic compound along an intersection between the seed layer and the alloying layer, the second intermetallic compound is formed as a precipitate within a solid solution of the seed layer and the alloying layer.
3. The method of claim 1 , wherein depositing the alloying layer comprises depositing chromium.
4. The method of claim 1 , wherein depositing the alloying layer comprises depositing at least one of the materials selected from the group consisting of chromium, tin, nickel, magnesium, cobalt, aluminum, manganese, titanium, zirconium, indium, palladium, and silver.
5. The method of claim 1 , wherein depositing the conductive material comprises depositing a material selected from the group consisting of copper, aluminum, and tungsten.
6. The method of claim 1 , further comprising:
depositing an electrically insulating liner along the sidewall and along the bottom of the opening between the nonmetallic material and the diffusion barrier.
7. The method of claim 1 , further comprising:
depositing a gold liner along the sidewall of the opening adjacent to and indirect contact with the seed layer before depositing the alloying layer.