Semiconductor device

Abstract

The present invention makes it possible to lower the on resistance of a semiconductor element without hindering the function of a diffusion prevention film in a semiconductor device having the semiconductor element that uses a wire in a wiring layer as a gate electrode and has a gate insulation film in an identical layer to the diffusion prevention film. A first wire and a gate electrode are embedded into the surface layer of an insulation layer comprising a first wiring layer. A diffusion prevention film is formed between the first wiring layer and a second wiring layer. A gate insulation film is formed by: forming a recess over the upper face of the diffusion prevention film in the region overlapping with the gate electrode and around the region; and thinning the part.

What is claimed is: 
     
         1 . A semiconductor device, comprising:
 a first wiring layer including first wirings embedded into a first interlayer insulating film;   a second wiring layer formed over the first wiring layer including second wirings and via electrodes embedded into a second interlayer insulating film;   a gate electrode comprised one of the first wirings;   a first gate insulating film formed between the first wiring layer and the second wiring layer and located over the gate electrode;   a second gate insulating over the first gate insulating film;   a diffusion prevention film covering the first wirings except the gate electrode and formed between the first wiring layer and the second wiring layer; and   a semiconductor film formed between the first wiring layer and the second wiring layer and located over the second gate insulating film;   wherein the second wirings are coupled to the semiconductor film through the via electrodes.   
     
     
         2 . The semiconductor device according to  claim 1 ,
 wherein the material for the second gate insulating film has a higher permittivity than the material for the first insulating film.   
     
     
         3 . The semiconductor device according to  claim 2 ,
 wherein the diffusion prevention film comprises SiN, SiCN, or SiC.   
     
     
         4 . The semiconductor device according to  claim 2 ,
 wherein the second gate insulating film includes an SiN layer, a composite metallic oxide layer having a perovskite structure, or a layer of oxide of one or more kinds of metals selected from the group consisting of Si, Al, Hf, Zr, Ta, and Ti.   
     
     
         5 . The semiconductor device according to  claim 1 ,
 wherein the first gate insulating film is formed by thinning a part of the diffusion prevention film located over the gate electrode.   
     
     
         6 . The semiconductor device according to  claim 1 ,
 wherein the gate electrode is Cu.   
     
     
         7 . The semiconductor device according to  claim 1 ,
 wherein source and drain are formed in the semiconductor film,   
       wherein the semiconductor film includes an oxide semiconductor film of InGaZnO layer, an InZnO layer, a ZnO layer, a ZnAlO layer, a ZnCuO layer, NiO, SnO, or CuO.