Method for removing native oxide and associated residue from a substrate

A method of processing a substrate disposed in a processing chamber, the method comprising:

• adjusting a substrate positioned in the processing chamber at a first temperature that prevents unwanted sublimation of solid byproducts;
• introducing a first gas mixture comprising nitrogen trifluoride (NF3) and ammonia (NH3) into a plasma chamber by flowing nitrogen trifluoride into the plasma chamber at a first flow rate and ammonia into the chamber at a second flow rate;
• generating a first cleaning plasma in the plasma chamber;
• condensing products of the first cleaning plasma onto the substrate while maintaining the substrate at the first temperature, thereby forming a thin film during a plasma clean process, wherein the thin film comprises ammonium hexafluorosilicate ((NH4)2SiF6) formed in part from a silicon oxide (SiOx) layer disposed on a surface of the substrate;
• heating the substrate to a second temperature greater than the first temperature within the processing chamber to remove the thin film from the substrate;
• and
• introducing a second gas mixture comprising nitrogen trifluoride into the plasma chamber by flowing nitrogen trifluoride into the plasma chamber at a third flow rate that is greater than the first flow rate;
• generating a second cleaning plasma from a second gas mixture using a second RF power, the second RF power being greater than the first RF power;
• and
• exposing the surface to products of the second cleaning plasma while maintaining the substrate at the second temperature.

A method of processing a substrate in a multi-chamber processing system, the method comprising the steps of:

• controlling a substrate positioned in a first chamber of the multi-chamber processing system to a first temperature that prevents unwanted sublimation of solid byproducts;
• generating a first cleaning plasma from a first gas mixture with a first plasma-generating power, the first gas mixture comprising nitrogen trifluoride (NF3) and ammonia (NH3);
• condensing products of the first cleaning plasma onto the substrate to form a thin film during a plasma clean process while controlling the temperature of the substrate at the first temperature, wherein the thin film comprises ammonium hexafluorosilicate ((NH4)2SiF6) formed in part from a silicon oxide (SiOx) layer disposed on a surface of the substrate;
• heating the substrate within the first processing chamber to a second temperature greater than the first temperature to remove the thin film from the surface;
• generating a second cleaning plasma from a second gas mixture with a second plasma-generating power, the second RF plasma-generating power being greater than the first plasma-generating power and the second gas mixture comprising nitrogen trifluoride;
• exposing the surface to products of the second cleaning plasma while the substrate is positioned in the first processing chamber and maintained at the second temperature;
• after the step of exposing the surface to products of the second cleaning plasma, transferring the substrate under vacuum from the first chamber to a second chamber of the multi-chamber processing system;
• and
• after the step of transferring the substrate, depositing a metal film on the surface.