Measurement of Local Strain in Thin Aluminium Interconnects Using Convergent Beam Electron Diffraction (CBED)

Energy filtered convergent beam electron diffraction (CBED) was used to investigate localized strain in aluminium interconnects. An analysis of the higher order Laue zone (HOLZ) line positions in CBED patterns makes it possible to measure the lattice strain with high accuracy (∼10−4) and high spatial resolution (10 to 100 nm). The strain development in a single grain was measured during thermal cycling between −170°C and + 100°C. The grain showed reversible, elastic behaviour over the whole temperature range building up large strains at low temperatures. By comparing with finite element simulations, a detailed understanding of the tri-axial strain state could be achieved.