High-Rate Reactive Ion Etching of SiO2 Using a Magnetron Discharge

Abstract

A magnetron discharge has been used for high-rate reactive ion etching. A SiO₂ wafer situated on the cathode was etched by scanning a rectangular permanent magnet under the cathode coupled with a power of 13.56 MHz which generated an intense plasma loop over the cathode. The SiO₂ etch rate of 1.1 µm/min and the SiO₂/Si selective ratio of 9.5 was achieved by employing CHF₃ under a magnetic field of 1 k Gauss and an input rf power of 1.6 W/cm². This condition lowers the ion bombarding voltage of 80 Å on the Si surface. The plasma scanning and an electrostatic chacking of the wafer to the wafer-cooled cathode produces an anisotropic etched feature without photoresist degradation.