Plasma etching method

Abstract

Abstract A method of plasma etching a gate stack on silicon with a chlorine-containing plasma precursor gas in a vacuum chamber fitted with an electrically conductive planar coil disposed outside the chamber and adjacent to a dielectric window mounted in a wall of the chamber, the conductive planar coil coupled to a first radiofrequency source that matches the impedance of the source to the coil, and a second radiofrequency source coupled to a substrate support mounted in the chamber in a direction parallel to the planar coil which comprises limiting the power during etching to 0-200 watts from the first radiofrequency source and to 50-200 watts from the second radiofrequency source. The resultant etch is anisotropic, and avoids charging of the substrate to be etched. When the gate stack comprises conductive polysilicon, the preferred plasma precursor etch gas is a mixture of hydrogen chloride and chlorine, when a highly selective etch is obtained.

Inventors

• 👤 Virinder S. Grewal

Bibliographic Details