N-channel field inversion has been investigated in large scale integrated chips fabricated by 0.65 mu m complementary metal oxide semiconductor double metal process in which spin-on-glass (SOG) is not etched back. Three kinds of organic SOG and two kinds of inorganic SOG were compared. Though n-channel field inversion is never observed in all structures at wafer completion, contrary to previous investigations, the inversion is observed only in organic SOG after storage under 140 degrees C/85% RH. H2O permeates the field oxide through organic SOG from chip sidewalls without sealing rings. Strained Si-O-Si bonds in the field oxide are most likely broken there by H2O yielding positive charges. The H2O also causes threshold voltage (V-t) shift of active transistors. Further, the H2O enhances transconductance degradation rather than H+ in inorganic SOG.