Monitoring the void formation in a process Damascence

Method for monitoring the void formation in a damascene interconnect process, the method comprising: Forming a test structure containing a first and a second series of multilevel damascene interconnect structures, said first and second series of multilevel damascene interconnect structures having a lower metal trench (110) and an upper metal trench (140), wherein the lower metal trench (110) and the upper metal trench (140) are interconnected by at least one passage (120), and wherein the first series of multilevel damascene interconnect structures having a varying width of the upper metal trenches (140) and a same width of the lower metal trenches (110), and the second series of multilevel damascene interconnect structures having a varying width of the lower metal trenches (110) and a same width of the upper metal trenches (140), said first and second series are formed in a one-dimensional array to provide the multilevel damascene interconnect structures on an intersection line; Cutting the test structure at the section line to show a cross-sectional view of the multilevel damascene interconnect structures; Observing the cross-sectional view; and Examine the void formation ...