NOVELTY - Processing a solar cell substrate (160) having a native oxide layer (170), involves: disposing the solar cell substrate in a processing chamber having walls; exposing the native oxide layer to a reactive fluorine containing gas mixture while maintaining a temperature of the substrate below a temperature of the walls; removing the native oxide layer; and depositing hydrogen, fluorine, or both on the substrate surface.    USE - For processing a solar cell substrate having a native oxide layer (claimed); for manufacturing solar cells; or for cleaning layers of solar cell substrates.    ADVANTAGE - In the solar cell manufacturing process, substrates are cleaned from time to time to remove oxidation and other impurities. The process is more efficient, and integrates well with an efficient overall production system. The method is beneficial for removing oxides from a silicon substrate prior to forming at least one layer on it, such as an amorphous silicon layer, a crystalline silicon layer, a high quality passivation layer or an anti-reflection coating layer; and improves passivation of a solar cell by improving the crystal structure of the solar cell at the interface with the passivation layer.    DETAILED DESCRIPTION - Processing a solar cell substrate (160) having a native oxide layer (170), involves: disposing the solar cell substrate in a processing chamber having walls; exposing the native oxide layer to a reactive fluorine containing gas mixture while maintaining a temperature of the substrate below a temperature of the walls; removing the native oxide layer; and depositing hydrogen, fluorine, or both on the substrate surface. The reactive fluorine containing gas mixture is an etchant gas mixture. The reactive fluorine containing gas mixture comprises hydrogen, nitrogen and active species. The active species comprise radicals. INDEPENDENT CLAIMS are included for the following:    (1) a method of processing a photovoltaic substrate, involving: in a first processing chamber of a cluster tool, exposing the substrate to a dry cleaning process comprising a deposition process, an etch process, and an anneal process to form a cleaned surface of the substrate; in a second processing chamber of the cluster tool, depositing a doped semiconductor layer on the cleaned surface of the substrate; and    (2) a method of forming a photovoltaic device, involving: forming a first silicon containing layer on a substrate; performing a dry cleaning process that removes impurities from a surface of the first silicon containing layer and deposits fluorine and/or hydrogen on the first silicon containing layer; and then forming a second silicon containing layer on the first silicon containing layer.    DESCRIPTION OF DRAWING(S) - The figure shows schematic side-views of a substrate.    Solar cell substrate (160)    Layer (170)    Hydrogen-terminated layer (190)