X-Ray Microbeam Studies of Electromigration

9708003嘉吉公司这项使用x射线微衍射和电子显微镜的电迁移研究建立在一年SGER NSF奖支持下工作期间获得的经验和信心的基础上。该工作表明，热迁移和电迁移引起的应变可以通过x射线微衍射成功地以10微米的空间分辨率和0.0002量级的应变灵敏度进行测量。过去的工作已经证实，在没有储层的导体线路中，电迁移过程中会出现线性应变梯度，并且在研究中使用的条件下，在电迁移的后期阶段会出现突然的应变松弛。新项目扩展了数量有限的工作10 micron-wide, 200微米长的纯Al导体线与竹子和更窄的线宽near-bamboo微观结构,较短的线应该能够维持较大的压力梯度,A1(铜)线,可以分别对铜电迁移和A1 x射线microfluorescence紧随其后,最后铜和铜(Sn)线、抗电迁移应该比A1(铜)。这项工作利用更高空间分辨率的X射线仪器将成分、微观结构和应变映射扩展到亚微米尺度，并允许在多晶导体线内对单个晶粒进行测量。该研究包括透射电子显微镜、扫描电子显微镜（SEM）和基于SEM的晶粒取向图观测，作为x射线微束微观结构、成分和应变图的补充。采用了具有真实微观结构和晶界扩散系数的有限元模型。该研究将扩展到短距离、微观结构相关的应变梯度，以及脉冲电流和反转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更好的实验基础。电迁移过程中应变分布的成功直接测量将为该领域进一步的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. ***