Disclosed is a capacitor with a dielectric layer having a low equivalent oxide thickness compared to a HfO.sub.2 layer and capable of decreasing a level of a leakage current incidence and a method for fabricating the same. Particularly, the capacitor includes: a bottom electrode; a Hf.sub.1-xLa.sub.xO layer on the bottom electrode; and a top electrode on the Hf.sub.1-xLa.sub.xO layer, wherein x is an integer. The method includes the steps of: forming at least one bottom electrode being made of polysilicon doped with impurities; nitriding a surface of the bottom electrode; depositing the amorphous Hf.sub.1-xLa.sub.xO layer on the nitrided surface of the bottom electrode; performing a thermal process for crystallizing the amorphous Hf.sub.1-xLa.sub.xO layer and removing impurities existed within the Hf.sub.1-xLa.sub.xO layer; nitriding a surface of the crystallized Hf.sub.1-xLa.sub.xO layer; and forming the top electrode being made of polysilicon doped with impurities on the nitrided surface of the crystallized Hf.sub.1-xLa.sub.xO layer.