Semiconductor device having barrier layer comprised of dissimilar materials, and method for fabricating the same

1. A semiconductor device, comprising:

a semiconductor substrate;

a capacitor having a lower electrode formed on said semiconductor substrate, a capacity insulating film formed on said lower electrode, and an upper electrode formed on said capacity insulating film;

contact holes formed on said upper electrode and said lower electrode;

a barrier layer containing oxygen, formed inside said contact holes, said barrier layer being a laminated structure of a plurality of layers, including a first barrier layer located on an electrode side, a third barrier layer formed on the first barrier layer, and a second barrier layer sandwiched between said first and third barrier layers, said first and third barrier layers being made of the same material, and said second barrier layer being made of a material different from said first and third barrier layer, said first and third barrier layers being made of TiN, and said second barrier layer being made of TiAlN; and

a conductive layer which fills said contact holes in which said barrier layer is formed on the inside.

2. A semiconductor device according to claim 1 , wherein said conductive layer is made of Al or an Al alloy.

3. A semiconductor device according to claim 1 , wherein said upper electrode and lower electrode are made of Pt.

4. A semiconductor device according to claim 1 , wherein said second barrier layer is in direct contact with said first barrier layer and said third barrier layer.