| 摘要 |
PURPOSE:To enable the high anisotropy, rapidity and pollution resistance to be simultaneously attained in silicon trench etching step. CONSTITUTION:The trench etching step is performed in the state wherein a silicon substrate is cooled down at the temperature below 0 deg.C using an etchant gas of S2F2 added S2Cl2. At this time, the etching reaction is anisotropically advanced mainly by ion assist reaction using ions such as Cl<->, etc., but the radical reaction is also advanced by a bit of F existing in the reaction system thereby enabling the rapid etching step to be performed. On the other hand, S produced in plasma by the discharge dissociation of said gas is deposited on the pattern sidewall part on the cooled down wafer surface thus contributing to the enhancement of the anisotropy. Furthermore, the deposited S can easily be removed by the temperature rise of the wafer or the oxygen plasma processing step so that the particles may not be polluted at all.
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