Highly Selective Si3N4/SiOC Etching Using Dual Frequency Superimposed RF Capacitively Coupled Plasma

概要

論文の詳細を見る
Highly selective etching of Si3N4 to SiOC film has been studied, using dual frequency superimposed (DFS) rf capacitively coupled plasma, which controlled the self-bias voltage ($-V_{\text{dc}}$) independently of electron density ($N_{\text{e}}$). The SiOC etch rate was effectively suppressed by fluorocarbon polymer deposition, which was controlled by the additive H2 gas flow rate ratio and carbon-to-silicon ratio of the SiOC film, without reduction in Si3N4 etching rate. Infinitely highly selective etching could be realized with a H2 gas flow rate ratio of above 50%. Stringent $V_{\text{dc}}$ control was required for line-and-space pattern etching in order to suppress the erosion of the SiOC pattern edge, even when a highly selective etching condition was used. The $V_{\text{dc}}$ range that was available for selective etching of Si3N4 to SiOC was as small as 150 V, which was approximately 50 V lower than that for selective etching of SiOC to Si3N. However, a much lower $-V_{\text{dc}}$, such as 100 V, caused excess deposition and taper etching. It was also found that lower $N_{\text{e}}$, which was controlled by a 100 MHz rf power, was required to suppress the excess deposition.
2006-07-15