Mechanical vibration assisted plasma etching for etch rate and anisotropy improvement

A novel plasma etching principle for etch rate and anisotropy improvement is proposed. A substrate vibration mechanism has been used to increase plasma collision energy and realize a better gas flow in the plasma etching reactor, as well as ultrasonic cleaning effects at the low vacuum. An reactive ion etching (RIE) system with an anode fixed to an ultrasonically vibrating support is used to demonstrate the principle. Two vibration frequencies of 28 and 38 kHz are applied to the substrate by changing vibration units, with vibration amplitudes of 13 and 9.3 μm, respectively. Etching experiments upon silicon substrates are performed by using SF6 gas with and without vibration. Vibration effects on etch rate and anisotropy are examined by SEM micrographs at cleaved cross-section of the etching holes. At present, the system is confirmed to have a maximum etch rate improvement of 78% from its original without vibration.