Electromigration in Thin Al Films

Abstract

The process of electromigration in thin Al films was studied directly by transmission electron microscopy during passage of current. Due to electromigration, the Al ions migrate along the test strip from cathode to anode, and the actual opening up of holes near the cathode was observed. The rate of hole formation was used to measure an activation energy. For the test strips, a value of 0.7 eV was obtained. In addition, some physical aspects of hole formation, as well as material buildup in the form of hillocks and single-crystal Al whiskers, were observed. Some of the whiskers, which were less than 1 μ in diameter, were seen to grow to unusual lengths, occasionally exceeding 50 μ.

Morphological evolution of Al whiskers grown by high temperature glancing angle deposition

“…Melmed and Gomer 9 and Barber 10 reported Al whisker growth on a hot tungsten wire and on the wall of a ceramic crucible, respectively, from pure Al vapor. However, there are few reports on the vapor growth of Al whiskers on a flat substrate, although it is possible to achieve the solid phase growth of Al whiskers on flat substrates by either electromigration 11,12 or stress-induced migration. 13,14 In these studies, it is reported that the whiskers are not grown on as-deposited films on a hot substrate.…”

Spontaneous growth of whiskers on RE-bearing intermetallic compounds of Sn-RE, In-RE, and Pb-RE

“…The spontaneous growth of metal whiskers from a solid surface is an interesting phenomenon which has been studied for many years [1][2][3][4][5][6], which was reported in many metals or alloys system such as Ag [1], Cd [2,3], Sn [4][5][6][7][8], Zn [9,10], Al [11], In [12], and Pb [13]. Among them, tin whiskers were extensively studied because both the Sn-based plating and solders have been widely used in electronic industry.…”

Real-Time TEM Imaging of the Formation of Crystalline Nanoscale Gaps

“…Figures 3(b) and 3(c) show two stages of the initial ''forward'' FCE, where a faceted nanogap has begun to form at a point on the left (''upstream'') side of the narrow constriction (movie S3 [15]). At this point we reverse the electron flow of the partially electromigrated lead [13]. Reversing the current causes the faceted nanogap region to refill with gold, demonstrating that the movement of the gold atoms during FCE is in the same direction as the electron flow [ Fig.…”