Semiconductor device having at least two layers of wirings stacked therein and method of manufacturing the same

1 . A semiconductor device having a first wiring formed in a first insulating layer and a second wiring formed in a second insulating layer formed on said first insulating layer and said first wiring,

at least one of said first wiring and said second wiring being a CuAl wiring,

said second wiring being electrically connected to said first wiring at its via-plug portion, with a plurality of barrier layers interposed between said second wiring and said first wiring, and

in said barrier layers, a CuAl-contact barrier layer which is in contact with said CuAl wiring having a nitrogen atom content of less than 10 atomic %.

2 . The semiconductor device according to claim 1 , wherein a first barrier layer which is in contact with said first wiring is selectively formed directly below the via-plug portion of said second wiring.

3 . The semiconductor device according to claim 1 , wherein a first barrier layer which is in contact with said first wiring is selectively formed directly on said first wiring.

4 . The semiconductor device according to claim 1 , having a multilayer wiring structure in which at least three layers of wirings are stacked, wherein said multilayer wiring structure has said first wiring and said second wiring.

5 . The semiconductor device according to claim 4 , wherein said multilayer wiring structure includes a lower-layer wiring layer and an upper-layer wiring layer, and a wiring in said lower-layer wiring layer is a CuAl wiring, and a wiring in said upper-layer wiring layer is a Cu wiring.

6 . The semiconductor device according to claim 1 , wherein at least one of said barrier layers has a nitrogen atom content of at least 10 atomic %.

7 . A method of manufacturing a semiconductor device, comprising the steps of:

preparing a first wiring formed in a first insulating layer;

forming a second insulating layer on said first insulating layer and said first wiring;

forming a trench for wiring and a via-hole which reaches said first wiring in said second insulating layer;

forming a plurality of barrier layers in said trench for wiring and said via-hole; and

forming a second wiring on said barrier layers,

at least one of said first wiring and said second wiring being formed of a CuAl alloy, and

in said barrier layers, a CuAl-contact barrier layer which is in contact with a CuAl wiring formed of said CuAl alloy having a nitrogen atom content of less than 10 atomic %.

8 . The method of manufacturing the semiconductor device according to claim 7 , wherein in the step of forming the plurality of said barrier layers, a first barrier layer which is in contact with said first wiring is selectively formed directly on a bottom surface of said via-hole.

9 . A method of manufacturing a semiconductor device, comprising the steps of:

preparing a first wiring formed in a first insulating layer;

selectively forming a first barrier layer directly on said first wiring;

forming a second insulating layer on said first insulating layer and said first barrier layer;

forming a trench for wiring and a via-hole which reaches said first barrier layer in said second insulating layer;

forming at least one additional barrier layer in said trench for wiring and said via-hole; and

forming a second wiring on said additional barrier layer,

at least one of said first wiring and said second wiring being formed of a CuAl alloy, and

a CuAl-contact barrier layer which is in contact with a CuAl wiring formed of said CuAl alloy having a nitrogen atom content of less than 10 atomic %.