ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The interdiffusion of Cu and Sn, and the formation and dissolution of Cu–Sn precipitates have been examined for Cu alloy films. Cu(Sn) films were deposited by electron beam evaporation either as Sn/Cu bilayers or Cu/Sn/Cu trilayers, with overall Sn concentrations from 0.1 to 5 at. %. In situ resistance, calorimetry, electron, and x-ray diffraction measurements indicate that η–Cu6Sn5 forms during film deposition. Upon heating, ε–Cu3Sn forms at 170 °C, then this phase dissolves into the Cu matrix at approximately 350 °C. Finally, ζ–Cu10Sn3 forms and precipitates after thermal cycling to 500 °C. The final resistivity of Cu/Sn/Cu films with more than 2 at. % Sn exceeds 3.5 μΩ cm. However, resistivities from 1.9 to 2.5 μΩ cm after annealing were reached in Cu/Sn/Cu films with less than 2 at. % Sn. Auger and Rutherford backscattering analysis of Cu/Sn bilayers (1 mm thick) showed that the homogenization of Sn in Cu requires annealing in excess of 350 °C for 30 min; after annealing, the Sn concentration at the surface is approximately 20 at. %. The interdiffusion of Sn and Cu is inhibited by contamination at the Sn/Cu interface caused by air exposure. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.366728
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