Pd/Cu(220) interdiffusion under compressive stress

Cheng Yi Liu, Chung Yu Chiu, Erh Ju Lin, Pai Jung Chang, Yue Kai Tang, Kun Hui Yang

Research output: Contribution to journalArticlepeer-review


This work investigates the effect of the external compressive pressure on the interdiffsuion between Pd and Cu. By analyzing ESCA atomic depth profiling without/with the external compressive pressure, two important findings were observed: (1) Pd/Cu(220) interdiffusion was found to be promoted by the external compressive pressure. (2) Under external compressive pressure, Pd atoms diffuse across the interdiffusion interface into the Cu(220) side more than the Cu atoms across the interdiffusion interface into the Pd side. Combining Matano approach and the obtained ESCA atomic profiles, the interdiffusion diffusivities and the activation enthalpy (H) of Pd/Cu(220) interdiffusion can be calculated. The activation enthalpy (0.694 eV) of Pd/Cu(220) interdiffusion is reduced to 0.625 eV and 0.604 eV with applying external pressures of 125 MPa and 250 MPa, respectively. The present calculation of the activation enthalpy implies that the applying compressive stress results in negative changes of the activation enthalpy (δH) and the free energy of activation (δG) for the Pd/Cu(220) interdiffusion. With Gibbs equation, the negative changes of δG and δH can further deduce the relation of the entropy change (δS) and the activation of enthalpy (δH) for the Pd/Cu(220) interdiffusion system under the external compressive stress, which are (1) the change of the entropy has to be positive (δS > 0) or (2) the change of the entropy (δS) has to be smaller than the term of δH/T., i.e., δS< δH/T.

Original languageEnglish
Article number124882
JournalMaterials Chemistry and Physics
StatePublished - 1 Oct 2021


  • Bonding
  • Diffusion
  • Electron spectroscopy for chemical analysis (ESCA)
  • Electronic packaging
  • Electroplating


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