Embodiments of the disclosure include methods for in-situ chamber cleaning a plasma processing chamber utilized for photomask plasma fabrication process. In one embodiment, a method for in-situ chamber cleaning after a plasma process includes supplying a cleaning gas mixture including at least an oxygen containing gas and a hydrogen containing gas into the plasma processing chamber, controlling the processing pressure at less than 2 millitorr, applying a RF source power to the processing chamber to form a plasma from the cleaning gas mixture, and cleaning the processing chamber in the presence of the plasma.