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 resistance variable memory device, comprising:
integrated circuitry formed over a substrate;
at least one insulating layer formed over said integrated circuitry, said insulating layer having a plurality of openings;
a plurality of electrical connections formed in the openings of said insulating layer;
at least one bond pad formed in an opening of said insulating layer;
a nickel cap formed over said bond pad; and
resistance variable memory cell material deposited over the insulating layer.
2. The device of claim 1 , wherein said bond pad comprises copper.
3. The device of claim 2 , wherein said nickel cap has a thickness of about 4000 Angstroms.
4. The device of claim 1 , wherein the memory device is a PCRAM memory device.
5. The device of claim 4 , wherein the memory cell material comprises layers of germanium selenide, chalcogenide glass and silver.
6. The device of claim 1 , further comprising an electrode layer located over said memory cell.
7. The device of claim 6 , wherein the electrode layer comprises one of tantalum and tungsten.
8. The device of claim 1 , wherein at least one of said plurality of electrical connections comprises a via filled with tungsten.
9. A memory system comprising:
a programmable conductive random access memory (PCRAM) memory device, said device comprising:
an array of PCRAM cells formed on a substrate; and
peripheral circuitry formed on the substrate and electrically connected to the array of PCRAM cells, said peripheral circuitry comprising a copper bond pad having a nickel cap.
10. The system of claim 9 , wherein said PCRAM cells comprise germanium selenide.
11. The system of claim 10 , wherein said PCRAM cells further comprise silver-containing layers.
12. The system of claim 9 , wherein said array of PCRAM cells comprises:
integrated circuitry formed over the substrate;
a bit line formed over the integrated circuitry;
at least one insulating layer formed over the integrated circuitry;
a plurality of electrical connections formed in the insulating layer to connect said integrated circuitry to PCRAM cell material; and
an electrode over the PCRAM cell material.
13. The system of claim 12 , wherein the PCRAM cell material comprises at least one layer of germanium selenide and at least one layer containing silver.
14. The system of claim 12 , wherein the electrode comprises one of tungsten and tantalum.
15. The system of claim 12 , wherein the plurality of electrical connections comprise a conductive via filled with tungsten.
16. The system of claim 12 , wherein the nickel cap has a thickness of about 4000 Angstroms.