Controlling dry etch process characteristics using waferless dry clean optical emission spectroscopy

A method for monitoring and controlling a waferless dry cleaning process performed during processing of a lot of production substrates in a plasma processing system, the method comprising:

• processing a first production substrate of the lot in a plasma processing chamber of the plasma processing system;
• after removing the first production substrate from the plasma processing chamber, flowing a dry cleaning gas into the plasma processing chamber of the plasma processing system;
• igniting a plasma in the plasma processing chamber to initiate a first instance of the waferless dry cleaning process;
• acquiring, during the first instance of the waferless dry cleaning process, optical emission spectra from an optical emission spectroscopy system attached to the plasma processing chamber;
• and
• processing a second production substrate of the lot in the plasma processing chamber of the plasma processing system;
• after removing the second production substrate from the plasma processing chamber, flowing the dry cleaning gas into the plasma processing chamber of the plasma processing system;
• igniting a plasma in the plasma processing chamber to initiate a second instance of the waferless dry cleaning process;
• acquiring, during the second instance of the waferless dry cleaning process, optical emission spectra from the optical emission spectroscopy system attached to the plasma processing chamber;
• adjusting at least one parameter of the second instance of the waferless dry cleaning process based on the acquired optical emission spectra of the first instance of the waferless dry cleaning process to provide a consistent cleanliness level of the plasma processing chamber during processing of the lot of production substrates.