Slit morphology of electromigration induced open circuit failures in fine line conductors

Abstract

Detailed transmission and scanning electron microscopic images of electromigration-induced open circuit failures are presented for fine line aluminum alloy thin film interconnects. A characteristic slit open circuit, similar to stress migration open circuits in narrow interconnects, is shown for various film compositions, processing, and deposition conditions. It is suggested that slit failure morphology is more generally observed for low (≊1) ratios of conductor line width to film grain size. The slit failures observed often occur near copper rich precipitates. The morphology of several slit voids suggests that they are transgranular across the linewidth, consistent with other recent reports of electromigration induced damage in single crystal interconnects.

Resistance behaviour and morphological changes during electromigration in gold wires

“…The breakdown of the wire finally occurs in a slit-like manner at the position of the highest current density (see figure 2(f)) with a gap of approximately 10 nm. Failure in a slit-like manner has been observed previously for polycrystalline, near-bamboo and single-crystalline aluminium wires [17,25,28,29]. In the case of the bamboo and single-crystalline wires, failure occurs often in a transgranular manner, indicating that stress migration might play a dominant role [30].…”

Hopf bifurcation, bistability, and onset of current-induced surface wave propagation on void surfaces in metallic thin films

“…Both experimental [3][4][5][6][7][8][9] and theoretical [10][11][12][13][14][15][16][17][18][19] studies have led to significant progress in understanding electromigration-driven void morphological evolution. Special emphasis has been placed on film failure due to electromigration instabilities leading to features, such as slits, emanating from the void surface [13][14][15][16][17][18][19].…”

A simulation of electromigration-induced transgranular slits

“…In addition to rounded voids, slits have been observed both in bamboolike and single-crystalline interconnects. [3][4][5] A void often nucleates at a junction of grain boundaries, or a junction of a grain boundary and an aluminum passivation interface. 6 The void may enlarge, migrate in a grain, penetrate grain boundaries, change shape, collapse to a slit, and finally sever the interconnect.…”