| CPC H01L 21/3065 (2013.01) [H01L 21/02236 (2013.01)] | 20 Claims |

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1. An semiconductor processing method comprising:
providing an oxygen-containing precursor to a processing region of a semiconductor processing chamber, wherein a substrate is housed within the processing region, and wherein a first layer of silicon-and-germanium-containing material, a second layer of silicon-and-germanium-containing material, and a layer of silicon-containing material are disposed on the substrate;
contacting the substrate with the oxygen-containing precursor, wherein the contacting oxidizes at least a portion of the second layer of silicon-and-germanium-containing material;
providing a first etchant precursor to the processing region;
contacting the substrate with the first etchant precursor, wherein the contacting selectively etches the first layer of silicon-and-germanium-containing material;
providing a second etchant precursor to the processing region; and
contacting the substrate with the second etchant precursor, wherein the contacting etches a portion of the layer of silicon-containing material.
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