Characterization of reactive ion etching of benzocyclobutente in SF 6/O 2 plasmas

Abstract

This paper reports the reactive ion etching (RIE) characteristics of benzocyclobutene (BCB) in sulfur hexafluoride/oxygen (SF 6/O 2) plasmas. The dependence of etching rate and etch anisotropy on the processing parameters, including RF power, chamber pressure, and SF 6 concentration, are investigated comprehensively ranging from 50 to 200 W, 22.5 to 270 mTorr, and 0% to 80%, respectively. The BCB etching rate increases with chamber pressure and RF power in spite of nonlinearity, but decreases with the increase in SF 6 concentration. Anisotropic etching can be achieved using low chamber pressure, large RF power, and high SF 6 concentration. To avoid grass-like residue that happens at low pressure and large power fluorine-poor conditions, processing parameters with respect to residue-free etching are recommended. The etching mechanisms of the dependence of the etching characteristics on the processing parameters are discussed. Optimal processing parameters are presented as a guideline for isotropic etching of BCB as sacrificial layers to release structures and for anisotropic etching of BCB to precisely control etching dimensions and profiles.