ZrO2 buffer layer and SrBi2Ta2O9 (SBT) thin films were deposited on the P-type Si(111) substrates by the R.F. magnetron-sputtering method. We studied the effect of the post-annealing of the ZrO2 buffer layer on the MFIS structure. We could conclude that the elements of Zr, Sr, Bi, and Ta etc. were diffused by the post-annealing, and according to the process with and without the post-annealing of the ZrO2 layer, the diffusion amount of Sr, Bi, Ta elements shows slight difference through the glow discharge spectrometer (GDS) analysis. From the results of the XPS analysis, we can confirm that a small amount of SiO2 and metallic Zr exist at the interface, and ZrO2 exists as the amorphous state with the weak binding energy before the post-annealing process. Contrarily, after the post-annealing of the ZrO2/Si structure, SiO2 and metallic Zr are observed at the wide range, but the bonding state of ZrO2 is strengthened.