In a thin film transistor, each of an upper electrode and a lower electrode is formed of at least one material selected from the group consisting of a metal and a metal nitride, represented by TiN, Ti, W, WN, Pt, Ir, Ru. A capacitor dielectric film is formed of at least one material selected from the group consisting of ZrO2, HfO2, (Zrx, Hf1-x)O2 (0<x<1), (Zry, Ti1-y)O2 (0<y<1), (Hfz, Ti1-z)O2 (O<z<l), (Zrk, Til, Hfm)O2 (0<k, l, m<1, k+l+m=1), by an atomic layer deposition process. The thin film transistor thus formed has a minimized leakage current and an increased capacitance.