difficult to electrically connect the first interconnection 18 and the second interconnection 28 as shown in fig5 f cu is buried in the second interconnection recess 24 using sputtering method or cvd method then the cu is polished until the second sio2 film 22 surface is exposed a second interconnection 28 which is made up of the cu as a second main interconnection the second tin film 26 and the second ti film 27 are formed in the second interconnection recess 24 thus the second interconnection 28 is connected to the first tin film 16 a and the first ti film 17 a fig6 is a plan view showing a damascene interconnection structure according to a third preferred embodiment of the invention fig7 is a cross sectional view showing a damascene interconnection structure according to a third preferred embodiment of the invention as shown in fig6 and fig7 a first interconnection 38 is preferably made up of a tin film 16 as a barrier layer a ti film 17 as a conductive layer and a first main interconnection 19 comprising cu the first interconnection 38 is formed in a first sio2 film 12 a second interconnection 48 is preferably made up of a tin film 26 as a barrier layer ti film 27 as a conductive layer and a.