Dielectric structure in nonvolatile memory device and method for fabricating the same

A method for fabricating a dielectric structure of a nonvolatile memory device, wherein the nonvolatile memory device includes a floating gate, the dielectric structure and a control gate, the method comprising:

• forming a first oxide layer on the floating gate;
• forming a first high-k dielectric film on the first oxide layer, wherein the first high-k dielectric film includes one selected from materials with a dielectric constant of approximately 9 or higher and a compound of at least two of the materials;
• forming a second oxide layer on the first high-k dielectric film;
• forming a second high-k dielectric film on the second oxide layer by employing a material identical to the first high-k dielectric film;
• and
• forming a third oxide layer on the second high-k dielectric film;
• wherein forming the first and the second high-k dielectric films comprises controlling a dielectric constant of at least one of the first and second high-k dielectric films by adjusting a feeding ratio of metal atoms composing the individual compounds of the at least one of the first and second high-k dielectric films such that the dielectric constant decreases as the feeding ratio increases and the dielectric constant is controlled to have a range of approximately 9 to 20 according to the feeding ratio.