Dry surface cleaning in integrated vacuum reactive ion etching processes

A study on dry cleaning in reactive ion etching (RIE) is conducted on a multichamber system consisting of several etch reactors. Particularly, the effects of a thin oxide residual layer on etch micromasking of selective silicon RIE are examined. An unintentionally grown oxide can be introduced, for example, during a resist removal process as well as an air exposure. To quantitatively evaluate surface cleanliness, a method for analyzing the formation of thin surface oxide is developed. The technique utilizes the selectivity property of a chlorine plasma to oxide. A criterion for a clean surface is defined based on the chlorine emission line intensity during a plasma exposure of a silicon surface. The effectiveness of a cleaning process, and its impact on the surface roughness following a selective silicon RIE process, are evaluated. © 1992, American Vacuum Society. All rights reserved.