Loading Effect and Temperature Dependence of Etch Rate in CF₄Plasma

Abstract

Plasma etching of silicon, silicon dioxide, and silicon nitride in CF4 and CF4+O2 (up to 20%) was evaluated concerning exposed area dependence and temperature dependence of the etch rate with a modified barrel type plasma reactor having a temperature-controlled sample holder which enabled samples to be etched one by one. Experimental results related to the exposed area dependence of the etch rate showed that the etching mode was divided into two regions; the loading effect region, and the intrinsic region. The behavior of the etch rate, the activation energy for the etch rate, and the etch rate ratio for silicon and silicon nitride over silicon dioxide were obtained. The pattern undercut with excess etch time was also examined, and it became evident that suppression of the loading effect and improvement of the pattern undercut could be achieved by lowering the sample temperature.