Title :
Microstructure evolution of tin under electromigration studied by synchrotron X-ray micro-diffraction
Author :
Wu, Albert T. ; Lloyd, J.R. ; Tamura, N. ; Tu, K.N.
Author_Institution :
Dept. of Mater. Sci. & Eng., UCLA, Los Angeles, CA, USA
Abstract :
Under constant current electromigration, white tin (P-Sn) exhibited a resistance drop of up to 10%. It has a body-center tetragonal (BCT) structure, and the resistivity along the a and b axes is 35% smaller than that along the c axis. Microstructure evolution under electromigration could be responsible for the resistance drop. Synchrotron radiation white beam X-ray microdiffraction was used to study this evolution. Both stress and grain orientation was studied. Grain-by-grain analysis was obtained from the diffracted Laue patterns about the changes of grain orientation during electromigration testing in ex-situ and in-situ samples. We observed that high resistance grains re-orient with respect to the neighboring low resistance grains, most likely by grain rotation of the latter. A different mechanism of microstructure evolution under electromigration from the normal grain growth is proposed and discussed.
Keywords :
X-ray diffraction; crystal microstructure; electric resistance; electromigration; electronics packaging; grain growth; granular structure; integrated circuit interconnections; synchrotron radiation; tin; Sn; body-center tetragonal structure; diffracted Laue pattern; electromigration; grain analysis; grain growth; grain orientation; grain rotation; resistance drop; resistivity; stress orientation; synchrotron X-ray microdiffraction; tin microstructure evolution; white tin; Conductivity; Electromigration; Immune system; Light sources; Microstructure; Strips; Synchrotron radiation; Tensile stress; Tin; Very large scale integration;
Conference_Titel :
Advanced Packaging Materials: Processes, Properties and Interfaces, 2005. Proceedings. International Symposium on
Print_ISBN :
0-7803-9085-7
Electronic_ISBN :
1550-5723
DOI :
10.1109/ISAPM.2005.1432073