Study of near-surface disorder and surface residues after reactive Ion etching of Silicon

Helium ion channelling, nuclear reaction profiling and x‐ray photoemission measurements of CF4/X%H2 (0≤X≤40) and CCIF3/50%H2 dry etched Si surfaces are reported. It is shown that plasma exposure of a clean Si surface leads to the deposition of a thin (∼30∼50) Å thick C,F‐containing film (or C,F, C1‐containing in the case of CC1F3/H2 etching). A subsurface Si carbide layer is formed during reactive ion etching. The near‐surface region (∼30∼50 Å) of the Si substrate is heavily disordered as found by ion channeling. A modified, less damaged layer containing a high concentration of hydrogen is formed in the case of the H2 containing gases (as shown by nuclear reaction profillin) and extends more than 250 Å from the surface. It is found that heating the plasma exposed substrates to 400°C in dry O2 for 30 min is efficient in recovering good quality Si surfaces.