Methods for forming low-resistivity interconnect structures comprising ruthenium

A method of forming interconnects in an integrated circuit (IC) device, the method comprising:

• forming a multilayer interconnect film stack on an underlying IC structure, wherein said forming the multilayer interconnect film stack comprises:
• performing a first deposition process to deposit a first conductive film above the underlying IC structure, the first conductive film comprising niobium (Nb);
• performing a second deposition process to deposit a second conductive film above and in contact with the first conductive film, the second conductive film comprising ruthenium (Ru), wherein the first conductive film increases a grain size and/or improves a crystalline orientation of the second conductive film during the second deposition process to decrease a resistivity of the second conductive film;
• etching the multilayer interconnect film stack to form a plurality of interconnects, each comprising the second conductive film formed above and in contact with the first conductive film;
• and
• depositing a dielectric layer on and between the plurality of interconnects.