초록

A method to selectively cap a cooper BEOL terminal pad with a Cu/Sn/Au alloy. The method includes providing one or more Cu BEOL terminal pads and coating the pads with a Sn coating followed by coating the Sn with a Au coating. The coated pads are then annealed to form the Cu/Sn/Au capping alloy.

대표청구항 ▼

1. A method to selectively cap the Cu terminal of a BEOL comprising:providing one or more Cu BEOL terminal pads;coating said pad with a layer of Sn by immersing in a selective immersion Sn plating bath;forming a coating of Au on said Sn layer; andannealing said Au and said Sn layers. 2. A method to

1. A method to selectively cap the Cu terminal of a BEOL comprising:providing one or more Cu BEOL terminal pads;coating said pad with a layer of Sn by immersing in a selective immersion Sn plating bath;forming a coating of Au on said Sn layer; andannealing said Au and said Sn layers. 2. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein forming a coating of Au comprises:immersing in an Au immersion plating bath. 3. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein forming a coating of Au comprises:immersing in an Au electroless plating bath. 4. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein annealing comprises heating in an oxidizing ambient. 5. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein said one or more Cu BEOL terminal pads are provided by the Damascene process. 6. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein said one or more Cu BEOL terminal pads are provided by the dual Damascene process. 7. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein said Sn plating bath comprises stannous chloride. 8. A method to selectively cap the Cu terminal of a BEOL, according to claim 7, wherein said Sn plating bath further comprises water, sulfuric acid, hypophosphite and thiourea. 9. A method to selectively cap the Cu terminal of a BEOL, according to claim 1 wherein said annealing said layers includes elevated temperatures at or below 300° C. 10. A method to selectively cap the Cu terminal of a BEOL, according to claim 1, wherein said annealing said layers provides a capping layer with a thickness from a few tens to a few thousands of Angstroms.