Dry etching results in the permeation of silicon by etching species; it also results in the better understood residue layer formation and near‐surface lattice damage layer formation. The principal species permeating silicon during dry etching exposures is found to be hydrogen. Using doping deactivation as a marker, we study this permeation and show that hydrogen can permeate as much as 10 μ during etching, thereby modifying the electrical properties of Si to that depth. We further demonstrate that this hydrogen permeation, at least in the case of pmaterial, exhibits two distinct regions of behavior and two apparent diffusion coefficients. It is also shown that the doping deactivation anneals out differently in these two permeation regions.