Applications of Automated High Resolution Strain Mapping in TEM on the Study of Strain Distribution in MOSFETs
Applications of Automated High Resolution Strain Mapping in TEM on the Study of Strain Distribution in MOSFETs
复制标题
TEM 中自动高分辨率应变映射在 MOSFET 应变分布研究中的应用
DOI：
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发表时间：
2014
期刊：
影响因子：
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通讯作者：
J. K. Weiss
中科院分区：
文献类型：
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作者：
A. Darbal;Raman D. Narayan;C. Vartuli;T. Aoki;J. Mardinly;S. Nicolopoulos;J. K. Weiss
通道中的工程应变是提高器件性能的一种具有成本效益的方法[1]。通过在硅中故意引入应变，改变带隙，这反过来又可以用来提高电子迁移率。可靠的沟道应变测量工具对于工艺开发至关重要。鉴于现代半导体器件的规模，透射电子显微镜（TEM）中的电子衍射非常适合此目的。特别是，纳米束衍射（NBD）是有趣的，因为它可以在高空间分辨率下获得NBD图案，并且在大多数现代TEM中相对容易设置[2]。然而，在传统的NBD模式的存在下，很难获得可靠的应变数据，因为光斑强度分布强烈依赖于局部试样的厚度和方向。这可以通过在获取衍射图案时旋进光束来克服[3]。随着旋进，入射光束围绕光轴倾斜和旋转（通常以100 Hz），使得动态效应被平均，并且在准运动学条件下获得衍射图案。此外，旋进电子衍射（PED）图案具有更好的高阶反射采样，这对晶格参数的微小变化更敏感。
Engineered strain in the channel is a cost effective means of improving the performance of devices [1]. Through deliberately introducing strain in silicon, the band gap is altered, which in turn can be used to enhance the electron mobility. A metrology tool for reliable channel strain determination is crucial for process development. Given the scale of modern semiconductor devices, electron diffraction in the transmission electron microscope (TEM) is well suited for this purpose. In particular, nanobeam diffraction (NBD) is interesting as it is possible to acquire NBD patterns at high spatial resolution and is relatively easy to set up in most modern TEMs [2]. However, the presence of strong dynamical effects in conventional NBD patterns makes it difficult to obtain reliable strain data as the spot intensity distributions are strongly dependent on local specimen thickness and orientation. This is overcome by precessing the beam as the diffraction patterns are acquired [3]. With precession the incident beam is tilted and rotated (typically at 100 Hz) about the optic axis so that the dynamical effects are averaged out and the diffraction patterns are acquired under quasi-kinematical conditions. In addition, precession electron diffraction (PED) patterns have better sampling of higher order reflections, which are more sensitive to small changes in lattice parameters.