Selective ruthenium removal by microwave oxidation plasma

A method of forming a film on a semiconductor substrate, comprising:

• a cyclic deposition-etch process, comprising:
• depositing a ruthenium layer over a bottom surface and sidewall surfaces that define an opening of a feature, wherein depositing the ruthenium layer comprises sequential exposure of the semiconductor substrate to an iodine-containing reactant, a purge gas, an organometallic precursor, and the purge gas;
• and
• trimming the ruthenium layer by exposing the ruthenium layer to a microwave plasma to remove at least a first portion of the ruthenium layer formed over the sidewall surfaces;
• and
• bottom-up growth of ruthenium from the ruthenium layer formed over the bottom surface.

A processing system, comprising:

• a first processing region;
• a second processing region;
• and
• a system controller, comprising:
• a memory for storing computer readable instructions;
• and
• a processor coupled to the memory, the processor configured by the computer readable instructions that when executed by the processor perform a plurality of operations, comprising:
• a cyclic deposition-etch process, comprising:
• depositing a ruthenium layer over a bottom surface and sidewall surfaces that define an opening of a feature on a semiconductor substrate in the first processing region;
• transferring the semiconductor substrate from the first processing region to the second processing region;
• and
• trimming the ruthenium layer by exposing the ruthenium layer to microwave radiation to remove at least a first portion of the ruthenium layer formed over the sidewall surfaces;
• and
• bottom-up growth of ruthenium from the ruthenium layer formed over the bottom surface.