Plasma oxidation of the c-Si substrate through a very thin gate oxide layer can be observed during HBr/O(2)/Ar based plasma overetch steps of gate etch processes. This phenomenon generates the so-called silicon recess in the channel and source/drain regions of the transistors. In this work, the authors compare the silicon recess generated by continuous wave HBr/O(2)/Ar plasmas and synchronous pulsed HBr/O(2)/Ar plasmas. Thin SiO(2) layers are exposed to continuous and pulsed HBr/O(2)/Ar plasmas, reproducing the overetch process conditions of a typical gate etch process. Using in situ ellipsometry and angle resolved X-ray photoelectron spectroscopy, the authors demonstrate that the oxidized layer which leads to silicon recess can be reduced from 4 to 0.8 nm by pulsing the plasma in synchronous mode. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3483165]