Semiconductor device and method of manufacturing semiconductor device

1. A semiconductor device, comprising:

a semiconductor substrate;

a first interconnect layer formed over the semiconductor substrate;

a gate electrode formed in the first interconnect layer;

a gate insulating film formed over the gate electrode;

a second interconnect layer formed over the gate insulating film;

an oxide semiconductor layer formed in the second interconnect layer; and

a via formed in the second interconnect layer and connected to the oxide semiconductor layer;

wherein the gate electrode, the gate insulating film and the oxide semiconductor layer overlap in a plan view;

wherein said oxide semiconductor layer includes a channel region formed in said oxide semiconductor layer;

wherein a trapping film is positioned over said oxide semiconductor layer; and

wherein a back-gate electrode is positioned over said trapping film, and overlaps with said channel region in a plan view.

2. The semiconductor device as claimed in claim 1 , wherein

said first interconnect comprises a copper interconnect,

said gate insulating film functions as a diffusion blocking film, and

said oxide semiconductor layer is formed over said diffusion blocking film.

3. The semiconductor device as claimed in claim 1 ,

wherein said oxide semiconductor layer, said gate insulating film, said gate electrode, said trapping film, and said back-gate electrode configure a memory element.

4. The semiconductor device as claimed in claim 1 , wherein said oxide semiconductor layer comprises at least one of an InGaZnO layer and a ZnO layer.

5. The semiconductor device as claimed in claim 1 , further comprising a MOS (metal-oxide-semiconductor) transistor-type element formed over said semiconductor substrate.

6. The semiconductor device as claimed in claim 5 , wherein at least a part of said MOS transistor-type element overlaps with said oxide semiconductor layer in a plan view.