Front-end processing of nickel plated bond pads
View Patent ↗A front-end method of fabricating nickel plated caps over copper bond pads used in a memory device. The method provides protection of the bond pads from an oxidizing atmosphere without exposing sensitive structures in the memory device to the copper during fabrication.
1. A method of forming an memory element, comprising the acts of:
forming integrated circuitry in a memory array; forming a plurality of insulating layers over the integrated circuitry; forming an electrical connection through each of said plurality of insulating layers to said integrated circuitry, wherein at least one of the electrical connections comprises a via filled with tungsten; etching at least one of said insulating layers to form an etched region; forming a copper bond pad in the etched region; plating the copper bond pad to form a cap over the bond pad; forming memory cells over the plurality of insulating layers but not over the bond pad; and forming an electrode over the memory cell.
2. The method of claim 1 , wherein the step of forming an electrode comprises blanket depositing a conductive material over the memory array.
3. The method of claim 1 , wherein the step of forming an electrode comprises depositing a conductive material over the memory array in a pre-determined pattern design.
4. The method of claim 1 , wherein the memory cells are programmable resistance memory cells.
5. The method of claim 4 , wherein the electrode comprises a conductive material that does not contain silver.
6. The method of claim 5 , wherein the electrode comprises one of tantalum and tungsten.
7. The method of claim 1 , wherein the step of plating the copper bond pad comprises exposing the bond pad to a nickel electroless plating bath.
8. The method of claim 1 , wherein the plating of the bond pad comprises forming a cap over the bond pad, wherein the cap has a thickness of about 4000 Angstroms.
9. The method of claim 8 , wherein the cap comprises nickel.
10. The method of claim 1 , further comprising the step of wet etching at least one of the plurality of insulating layers subsequent to said plating step.
11. The method of claim 10 , wherein the step of wet etching creates exposure to a top surface of the tungsten filled electrical connection.
12. A method of forming a memory element, comprising the acts of:
forming a copper bond pad over integrated circuitry formed in a substrate;
forming at least one insulating layer over the integrated circuitry;
removing a portion of the at least one insulating layer from a region over the copper bond pad;
forming a nickel cap in the region over the copper bond pad by electrolessly plating the copper bond pad with nickel; and
subsequently forming at least one memory cell material over and electrically connected to the integrated circuitry.
13. The method of claim 12 , wherein the at least one memory cell material comprises resistance variable memory cell materials.
14. A method of forming a memory element, comprising the acts of:
forming a copper bond pad over integrated circuitry formed in a substrate;
forming at least one insulating layer over the integrated circuitry;
removing a portion of the at least one insulating layer from a region over the copper bond pad;
forming a nickel cap in the region over the copper bond pad; and
subsequently forming at least one memory cell material over and electrically connected to the integrated circuitry,
wherein the at least one memory cell material comprises at least one layer of chalcogenide glass.
15. The method of claim 14 , wherein the at least one memory cell material further includes a silver-containing layer.
16. The method of claim 14 , wherein the at least one layer of chalcogenide glass comprises germanium selenide.
17. A method of forming a memory element, comprising the acts of:
forming a copper bond pad over integrated circuitry formed in a substrate;
forming at least one insulating layer over the integrated circuitry;
removing a portion of the at least one insulating layer from a region over the copper bond pad;
forming a nickel cap in the region over the copper bond pad;
subsequently forming at least one memory cell material over and electrically connected to the integrated circuitry; and
forming an electrode layer over the at least one memory cell material.
18. The method of claim 17 , wherein the electrode layer comprises one of tantalum and tungsten.