US Patent 10497573 Selective atomic layer etching of semiconductor materials

Precursors, such as interhalogens and/or compounds formed of noble gases and halogens, may be supplied in a gaseous form to a semiconductor processing chamber at a predetermined amount, flow rate, pressure, and/or temperature in a cyclic manner such that atomic layer etching of select semiconductor materials may be achieved in each cycle. In the etching process, the element of the precursor that has a relatively higher electronegativity may react with select semiconductor materials to form volatile etching byproducts. The element of the precursor that has a relatively lower electronegativity may form a gas that may be recycled to re-form an precursor with one or more halogen-containing materials using a plasma process.