The present invention provides an apparatus and process for plasma cleaning the interior surfaces of semiconductor processing chambers. The method is directed to the dry etching of accumulated contaminant residues attached to the inner surfaces of the plasma processing chamber and includes introducing a cleaning gas mixture of a halogen-containing gas; activating a plasma in an environment substantially free of oxygen species; contacting the contaminant residues with the activated cleaning gas to volatilize the residues; and removing the gaseous by-products from the chamber. The etchant gaseous mixture comprises an even or greater amount of at least one fluorine-containing gas and an even or lesser amount of at least one chlorine-containing gas. The instant invention enables the intermittent use of the cleaning steps in an ongoing plasma processing of semiconductor wafers without chamber downtime and significant loss of wafer production.