Triple Junction Engineering: the Distribution of Triple Junctions in Polycrystalline Gold Thin Films
- PDF / 933,027 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 115 Downloads / 170 Views
1
and ALEXANDER H. KING 2
1. Department of Materials Science and Engineering, SUNY Stony Brook, NY 11794-2275. 2. School of Materials Engineering, Purdue University, West Lafayette, IN 47907-1289. ABSTRACT We have investigated compliance with the I-product rule at triple junctions with a common [I ll ] axis using computer simulations and in real thin films, using electron microscopy. Large discrepancies exist between the simulations, which assume randomly distributed misorientations, and the experiments. Although for both cases the rule fails at most triple junctions, the real material shows a much higher than expected occurrences of compliance. This result can be explained in two distinct ways: first, there might be a preference for triple junctions that obey the rule (implying a distinct influence of the triple junction itself). Alternatively, the misorientations in the real crystal might not be randomly distributed: if there is a preference for boundaries that have only small deviations from coincidence, there will be an increase in the compliance with the rule. INTRODUCTION Grain boundaries are interfaces between identical crystals (or grains) that have different orientations. They cannot terminate inside a specimen and in polycrystalline materials, three boundaries meet in a line to form a triplejunction. The properties of these junctions have been studied with increasing intensity in recent years. Metal thin films that are commonly used in the electronic industries as interconnects in integrated circuits exhibit a strong texture with one of the low index directions (100), (110) and (111) perpendicular to the film surface [I]. The grain boundaries of these films are usually perpendicular to the surface and the rotation axis is parallel to the boundary plane and also parallel to the common film normal [2,3]. Triple junctions are important defects in these films since they are associated, for example, with electromigration damage. Thin film specimens conversely provide a convenient medium for the investigation of triple junctions, since they provide a large variety of junctions which embody grain boundaries that have the same axes of rotation, providing a convenient subset of all possible triple junctions that is more tractable than the global set of all triple junctions which might be expected in a three-dimensional polycrystal exhibiting a random misorientation distribution function. In this work, we have used a computer program to catalog all the possible special triple junctions with a common [111 ] axis, corresponding to a well-annealed fcc metal thin film, and tested the validity of the X-product rule (described below) for each and every junction. We have also compared the results of the validity test with the results of an investigation conducted using real polycrystalline gold thin films. Distribution of Coincidence Boundaries for (111) Textured Films In (11l) textured films, Brandon's criterion, allows almost every grain boundary to be classified as a coincidence-related boundary [3, 4]. Polycrystalli
Data Loading...
