US Patent 9406523 Highly selective doped oxide removal method

A method of etching doped silicon oxide on patterned heterogeneous structures is described and includes a gas phase etch using partial remote plasma excitation. The remote plasma excites a fluorine-containing precursor and the plasma effluents created are flowed into a substrate processing region. A hydrogen-containing precursor, e.g. water, is concurrently flowed into the substrate processing region without plasma excitation. The plasma effluents are combined with the unexcited hydrogen-containing precursor in the substrate processing region where the combination reacts with the doped silicon oxide. The plasmas effluents react with the patterned heterogeneous structures to selectively remove doped silicon oxide.