Preclean methodology for superconductor interconnect fabrication

A method of forming a superconductor device interconnect structure, the method comprising:

• disposing a superconducting interconnect layer in a preclean chamber, the superconducting interconnect layer having a superconducting contact or conductive line having a top surface aligned with a top surface of a first dielectric layer, wherein a top surface of the superconducting contact or conductive line has an oxidized layer, wherein the superconducting material employed to form the superconducting contact or conductive line is niobium (Nb) and the oxidized layer is niobium oxide;
• introducing tetrafluoromethane (CF4) gas into the preclean chamber;
• setting etch conditions to induce a plasma clean etch with the tetrafluoromethane (CF4) gas for a predetermined time period to break the oxidized layer from the superconducting contact or conductive line to produce niobium fluoride (NbF5) gas and oxygen (O2) gas that evaporates off the surface of the niobium to form a clean niobium top surface;
• disposing the interconnect layer in a deposition chamber;
• and
• depositing a second dielectric over the interconnect layer.

A method of forming a superconductor device interconnect structure, the method comprising:

• depositing niobium in openings in a first dielectric layer overlying a substrate to form one or more superconducting interconnect elements in the first dielectric layer;
• performing a chemical mechanical polish (CMP) to align a top surface of the one or more superconducting interconnect elements with a top surface of the first dielectric layer, wherein the CMP causes oxidization on a top surface of the one or more superconducting interconnect elements;
• performing a plasma clean on the oxidation by introducing tetrafluoromethane (CF4) gas into an environment of the first dielectric layer and setting etch conditions to induce a plasma clean etch with the tetrafluoromethane (CF4) gas;
• and
• depositing a second dielectric over the first interconnect layer.

A method of forming a superconductor device interconnect structure, the method comprising:

• forming a first dielectric layer overlying a substrate;
• forming a superconducting interconnect element in a first dielectric layer, the interconnect element having a top surface aligned with a top surface of the first dielectric layer to form a first interconnect layer comprises forming openings in the first dielectric layer;
• performing a contact material fill to fill the formed openings;
• performing a chemical mechanical polish (CMP) to align a top surface of the superconducting interconnect element with a top surface of the first dielectric layer;
• performing a cleaning process on a top surface of the first interconnect layer, wherein the cleaning process is a tetrafluoromethane (CF4) based plasma clean etch process that removes oxidation on a top surface of the superconducting interconnect element caused by the CMP;
• and
• depositing a second dielectric over the first interconnect layer.