S. Tobe et al., EQUILIBRIUM-CONSTANT OF SEGREGATION-INDUCED FE GETTERED BY HEAVY BORON DOPING IN SI, Journal of applied physics, 84(3), 1998, pp. 1279-1283
The equilibrium constant of segregation-induced Fe gettering by heavy
boron (B) doping in Si is obtained by experimental determination of th
e activation energy and the site density parameter of the gettering re
action. The activation energy is determined to be 0.68+/-0.03 eV by an
alyzing the temperature dependence of the equilibrium constant of the
reaction. This result indicates that the Fe gettering is strongly rela
ted to formation of the Fe-B complex whose binding energy is very clos
e to the value determined for the activation energy. Furthermore, the
gettering site density is found to be proportional to the doped B conc
entration in the substrate crystal. It is understood from the activati
on energy value that the Fe gettering ability of each reaction site fo
r heavy B doping is less than that for thin polycrystalline Si film on
the back surface of a substrate. The well known high overall getterin
g capability of the heavily B-doped substrate is not simply due to the
activation energy effect it is predominantly due to a large number of
gettering sites in the overall region of the substrates and the close
ness of the impurity Fe to the gettering sites. (C) 1998 American Inst
itute of Physics.