Effect of interface layer on the microstructure and electromigration resistance of Al-Si-Cu alloy on TiN/Ti substrates

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Abstract
Al‐Si‐Cu alloy films sputter‐deposited on reactively ion‐sputtered TiN/Ti/SiO2 substrates were characterized and evaluated for interconnect reliability. Using x‐ray diffraction techniques, both TiN and Al microstructures were analyzed and the (111) intensities of the latter correlated with the electromigration median time to fail (MTTF). The values of the MTTF increased with the Al(111) intensities for the TiN/Ti/SiO2 substrates annealed below 400 °C. A progressive decrease in both the Al(111) texture and MTTF was observed for substrates annealed above this temperature. While the improved Al(111) texture has been attributed to an improved TiN barrier textured in the (111) crystal plane (anneals below 400 °C), a TiO2 layer over the TiN barrier has been found responsible for the degradation of the Al(111) texture and the MTTF for barrier anneals above 400 °C.