We discuss the electrical reliability and the spectral shape of the in
frared absorption in SiO2 and then using the percolation theory presen
t a new theoretical approach to the dielectric breakdown. We show the
significant oxide thickness dependence of oxide deteriorations and a u
niversal temperature dependence of the charge-to-breakdown, irrespecti
ve of the injection polarity or the oxide growth condition. On the oth
er hand, the thickness dependence of IR absorption spectra indicates a
spectral shape broadening into the lower energy near the Si/SiO2 inte
rface. These findings are physically investigated and, using the perco
lation theory, incorporated into a breakdown model of the a-SiO2 with
randomly distributed bond strength.