Inert-dominant pulsing in plasma processing systems

A method for processing a substrate in a plasma processing chamber of a plasma processing system, said plasma processing chamber having at least one plasma generating source and at least a gas source for providing a process gas into an interior region of said plasma processing chamber, comprising:

• exciting said plasma generating source with an RF signal having an RF frequency;
• and
• pulsing said gas source, using at least a first gas pulsing frequency, such that a first process gas is flowed into said plasma processing chamber during a first portion of a gas pulsing period associated with said first gas pulsing frequency and a second process gas is flowed into said plasma processing chamber during a second portion of said gas pulsing period associated with said first gas pulsing frequency, said second process gas having a lower reactant-gas-to-inert-gas ratio relative to a reactant-gas-to-inert-gas ratio of said first process gas, wherein said second process gas is formed by removing at least a portion of a reactant gas flow from said first process gas.