Title :
Gold-Aluminum Intermetallic Formation Kinetics
Author :
Blish, Richard C., II ; Li, Susan ; Kinoshita, Hiro ; Morgan, Sheila ; Myers, Alline
Author_Institution :
Adv. Micro Devices, Inc., Sunnyvale, CA
Abstract :
Au-Al intermetallic compounds (IMC) grow laterally (Al-rich phases) in a Fickian fashion with an activation energy of 1.0 eV, but vertical IMC thickness (Au-rich phases) grows functionally as a power law on time with a sub-Fickian exponent of ~frac14, substantially smaller than what would be expected for bulk, lattice diffusion (1/2). We conclude from the IMC thickness time exponent that Au-rich IMC growth process is limited by grain boundary diffusion. The best bond lifetime was seen for an intermediate thickness Al film. The activation energy and lifetime for Au-rich phase growth are each a strong function of wire impurity concentrations. We find that bond lifetime varies roughly as the square root of Pd, Cu, Pt and As concentrations, but lifetime is not a function of Be, Ca, Fe or Cr concentration. We find a mixture of Au 4Al and Au on the Al-rich side of the failing interface
Keywords :
alloying; aluminium alloys; arsenic alloys; beryllium alloys; calcium alloys; chemical interdiffusion; chromium alloys; copper alloys; gold alloys; grain boundary diffusion; iron alloys; metallic thin films; palladium alloys; platinum alloys; reliability; surface chemistry; wires (electric); 1.0 eV; As; Au-Al; Be; Ca; Cr; Cu; Fe; Fickian fashion; Pd; Pt; activation energy; bond lifetime; failing interface; grain boundary diffusion; intermetallic formation kinetics; phase growth; wire impurity concentrations; Bonding; Chromium; Gold; Grain boundaries; Impurities; Intermetallic; Iron; Kinetic theory; Lattices; Wire;
Conference_Titel :
Reliability Physics Symposium Proceedings, 2006. 44th Annual., IEEE International
Conference_Location :
San Jose, CA
Print_ISBN :
0-7803-9498-4
Electronic_ISBN :
0-7803-9499-2
DOI :
10.1109/RELPHY.2006.251222