The dielectric properties, which are highlighted on electrical characteristics, of alpha-Si/CO/SiO2/Si Structure after thermal annealing have been studied. A one-step high temperature (greater-than-or-equal-to 700-degrees-C) annealing process is found to deteriorate considerably the characteristics of the masking oxide. The tetraethylorthosilicate oxide needs a high-temperature preanneal prior to the self-aligned silicided (SALICIDE) process in order to prevent crack and pit formation and severe electrical degradation during silicidation annealing. A two-step annealing process with the first annealing performed at 550-degrees-C for 30 min has proved to be a trustworthy salicide process without affecting the dielectric properties of masking oxide.