Inverse RIE Lag during Silicon Etching in SF6 + O2 Plasma

R. Knizikevičius Department of Physics, Kaunas University of Technology, 73 K. Donelaičio Str., LT-44249 Kaunas, Lithuania

Received: July 4, 2019; in final form December 29, 2019

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The reactive ion etching of silicon in SF6+O2 plasma is considered. The etched trench profiles are calculated as a function of mask dimensions, flux of reactive plasma species, and ion bombardment parameters. It is found that with the increase in O2 content aspect ratio and etching anisotropy initially decrease. 30% O2 in the feed is required to suppress chemical etching of side walls, and to restore the values of aspect ratio and etching anisotropy downgraded by the increased chemical etching. With further increase in O2 content aspect ratio and etching anisotropy increase. Later, the aspect ratio starts to decrease due to the accumulation of SiO2 molecules in the trench bottom and inverse reactive ion etching lag takes place.

DOI:10.12693/APhysPolA.137.313 topics: SF6\, +\, O2 plasma, silicon, inverse RIE lag