Fraunhofer-Center Nanoelectronic Technologies, 01099 Dresden, Germany.
Ultramicroscopy. 2011 Nov;111(11):1630-5. doi: 10.1016/j.ultramic.2011.08.009. Epub 2011 Sep 16.
The spatial resolution and high sensitivity of tip-enhanced Raman spectroscopy allows the characterization of surface features on a nano-scale. This technique is used to visualize silicon-based structures, which are similar in width to the transistor channels in present leading-edge CMOS devices. The reduction of the intensive far-field background signal is crucial for detecting the weak near-field contributions and requires beside a careful alignment of laser polarization and tip axis also the consideration of the crystalline sample orientation. Despite the chemical identity of the investigated sample surface, the structures can be visualized by the shift of the Raman peak positions due to the patterning induced change of the stress distribution within lines and substrate layer. From the measured peak positions the intrinsic stress within the lines is calculated and compared with results obtained by finite element modeling. The results demonstrate the capability of the tip-enhanced Raman technique for strain analysis on a sub-50nm scale.
尖端增强拉曼光谱具有空间分辨率高和灵敏度高的特点，允许对纳米级表面特征进行表征。这项技术用于可视化基于硅的结构，其宽度与目前领先的 CMOS 器件中的晶体管通道相似。为了检测弱近场贡献，必须减少强远场背景信号，这除了需要仔细调整激光偏振和尖端轴的对准外，还需要考虑晶体样品的取向。尽管研究样品表面的化学性质相同，但通过由于图案化引起的线和衬底层内的应力分布变化导致的拉曼峰位置的移动，可以对结构进行可视化。从测量的峰位置计算线内的固有应力，并将其与有限元建模获得的结果进行比较。结果表明，尖端增强拉曼技术具有在亚 50nm 尺度上进行应变分析的能力。
