Provided is a semiconductor device comprising: an HSQ layer formed on a Cu
wiring line and having properties that Cu is unlikely to enter the HSQ
layer; a plug formed in the HSQ layer and connected to the Cu wiring
line; and a Cu wiring line inserted inside the HSQ layer and connected to
the plug. A W layer which allows the plug and the HSQ layer to adhere to
each other is formed between the plug and the HSQ layer, and another W
layer which allows the Cu wiring line and the HSQ layer to adhere to each
other and which is formed of tungsten is formed between the Cu wiring
line and the HSQ layer.