Plastic Deformation in Thin Copper Films Determined by X-Ray Micro-Tensile Tests

Abstract

Plastic deformation in thin copper films has been studied at room temperature. Copper films having a thickness of 1 μm were made by sputtering onto nickel substrates with a Si3N4 underlayer and with or without a Si3N4 caplayer. Deformation experiments were conducted using a special micro-tensile tester built into a θ–θ diffractometer. The problems normally associated with tension tests of free-standing films were avoided by deforming the substrate and film together. In-situ x-ray measurements of the lattice spacings and lattice spacing distributions were used to determine both elastic and plastic strains. The effects of caplayer and annealing temperature on mechanical properties are reported.

Interconnect failure due to cyclic loading

“…Owing to the sample structure, the film stress cannot be determined from the externally applied load. Therefore, the stress-strain behavior of the films is analyzed using in-situ X-ray diffraction during straining of the samples [5,7]. shows the first cycle from such a tensile test on a 1 µm thick Cu film.…”

Mechanical Testing of Thin Films and Small Structures

“…[56,57] Another approach has been introduced by Schadler and Noyan, [58] who used in-situ stress measurement by XRD, as described in the section on thermal cycling, during the tensile test. For these experiments, both plastically deforming substrates of Ni sheets [58,59] and elastic substrate of polyimide foils [60] have been used. Figure 6 shows a typical example from a tensile test of 1.5 lm thick Cu film on a polyimide foil, measured using the sin 2 w-method.…”

Mechanical characterization of nanostructured thin films at different scales

“…Thus, understanding the mechanical behaviour of nanostructured thin films is of utmost importance for ensuring the reliability of systems. Amongst specialized techniques for mechanical characterization of supported thin films, in-situ tensile testing has been proven to be the most suitable method [9][10][11][12][13][14][15][16]. Uniaxial testing commonly used generates a non-equi-biaxial state in the film due to Poisson's ratios mismatch between the substrate and the metallic thin film.…”