Semiconductor memory device and production method thereof

1. A semiconductor memory device comprising:

a memory cell array, the memory cell array including:

a first conductive layer which is arranged in a first direction above a first semiconductor layer;

a second conductive layer which is arranged in the first direction above the first conductive layer;

a columnar second semiconductor layer which extends in the first direction; and

a contact unit which electrically connects the first semiconductor layer and the second conductive layer,

the contact unit including:

a first film which contains silicide as a first metal, and is in contact with the first semiconductor layer;

a second film which contains the first metal, is in contact with the first film, and is in contact with the first semiconductor layer with the first film interposed therebetween:

a third film; and

a fourth film which is arranged in the first direction side by side with the third film, and extends in the first direction, and

the second film being in contact with an upper surface, a bottom surface, and a side surface of the third film.

2. The semiconductor memory device according to claim 1 , wherein

the first film is arranged from a bottom surface of the contact unit to be equal to or upper than an upper surface of the first semiconductor layer in the first direction, and contains the silicide as the first metal across an entire surface from a bottom surface to an upper surface of the first film.

3. The semiconductor memory device according to claim 1 , wherein the first metal is titanium (Ti).

4. The semiconductor memory device according to claim 1 , wherein the second film contains the first metal which is nitrided.

5. The semiconductor memory device according to claim 1 , wherein

the third film contains polysilicon (Poly-Si), and

the fourth film contains tungsten (W).