X-Ray Microbeam Studies of Electromigration

小行星9708003 这项使用X射线微衍射和电子显微镜的电迁移研究建立在为期一年的SGER NSF奖支持的工作期间获得的经验和信心的基础上。 这项工作表明，热和电迁移引起的应变可以成功地测量与10微米的空间分辨率和应变灵敏度的顺序为0.0002的X射线微衍射。 过去的工作已经证实，线性应变梯度发展过程中的电迁移在没有水库的导体线路和突然的应变松弛发生在电迁移的后期阶段的研究中使用的条件下。 该新项目将有限数量的10微米宽、200微米长的纯Al导体线的工作扩展到具有竹子和近竹子微观结构的较窄线宽，扩展到应该能够承受较大应变梯度的较短线，扩展到A1（Cu）线，其中Cu和A1的电迁移可以分别通过X射线显微荧光进行，最后是Cu和Cu（Sn）线，它们应该比Al（Cu）更耐电迁移。 这项工作利用更高的空间分辨率的X射线仪器，以扩大组成，微观结构和应变映射到亚微米尺度，并允许测量多晶导体线内的单个晶粒。 该研究包括透射电子显微镜、扫描电子显微镜（SEM）和基于SEM的晶粒取向映射观察，作为对X射线微束显微结构、组成和应变映射的补充。 采用有限元建模与现实的微观结构和取向差依赖晶界扩散系数。 这项研究将扩展到短范围，微观结构相关的应变梯度，以及脉冲和反向电流对电迁移应变的影响。 本研究的预期意义在于为理解电迁移提供了一个较好的实验基础。 电迁移过程中应变分布的成功直接测量将为这一领域的进一步理论工作提供测试和重点。 ***

9708003 Cargill This study of electromigration using X-ray microdiffraction and electron microscopy builds on the experience and confidence gained during work supported by a one-year SGER NSF award. This work has shown that thermal and electromigration induced strains can be successfully measured with 10 micron spatial resolution and with strain sensitivities on the order of 0.0002 by X-ray microdiffraction. The past work has confirmed that linear strain gradients develop during electromigration in conductor lines with no reservoirs and that abrupt strain relaxation occurs during the later stages of electromigration under the conditions used in the studies. The new project extends the work on a limited number of 10 micron-wide, 200 micron-long pure Al conductor lines to narrower line widths with bamboo and near-bamboo microstructures, to shorter lines which should be able to sustain larger strain gradients, to A1(Cu) lines where electromigration of Cu and of A1 can be separately followed by X-ray microfluorescence, and finally to Cu and Cu(Sn) lines, which should be more resistant to electromigration than A1(Cu). The work utilizes higher spatial resolution X- ray instrumentation to extend composition, microstructure and strain mapping to the submicron scale and to permit measurements on single grains within polycrystalline conductor lines. The study includes transmission electron microscopy, scanning electron microscopy (SEM), and SEM- based grain orientation mapping observations as complements to the X-ray microbeam microstructure, composition, and strain mapping. Finite element modeling is employed with realistic microstructures and misorientation dependent grain- boundary diffusivities. The study will be extended to short range, microstructure related strain gradients, and to effects of pulsed and reversal current on electromigration strains. %%% The expected significance of the research is that it provides a better experimental base for underst anding electromigration. Successful direct measurements of strain distributions during electromigration will provide tests and focus for further theoretical work in this area. ***