Samarium influence on current induced atomic displacement in Aluminium and Copper combinatorial thin film alloys

Gallium-Enhanced Aluminum and Copper Electromigration Performance for Flexible Electronics

“…Studying Al–Cu thin film libraries, maximum current density ( j max ) values up to 0.9 MA cm –2 were found on similar test wire designs. 32 In the present work, both Al–Ga and Cu–Ga have showed better performances with j max values above 1 and 1.5 MA cm –2 , respectively. However, the values obtained from the Al–Cu–Ga ternary library screening reached only a maximum of 0.7 MA cm –2 .…”

“…These values are of no real interest for actual high current applications because a current density as high as 1.3 MA cm –2 could be achieved on pure Al test wires. 32 However, diagonally across this region, values of j max exceeding 1.1 MA cm –2 are observable in the mapping. The Al–Ga alloy with the highest ability to withstand electromigration was identified as Al-8 at.…”

“…This accumulation may be responsible for the noted increase in electromigration resistance since the presence of Ga may inhibit the continuous grain growth under high electron fluxes, as previously imaged in pure Al films. 32 …”

“…The same behavior is observed during electromigration in pure Al. 32 The combined influence of these two forces changes the growth direction of the grain boundaries as schematically described in Figure 7 . However, unlike the case of pure Al, the presence of Ga triggers a fragmentation of the grain boundaries leading to the currently modeled grain behavior.…”

“…Species with large atomic sizes (such as rare earths) may be considered in an attempt to increase the entropy of Al or Cu thin film alloys, decreasing the total grain boundary area on the surface and thus restricting void formation. 32 Gallium can also be such an alloying element. Pure Ga has a very low melting temperature of 29.8 °C and is highly soluble in Al, up to 20 wt % (9 at.…”