Low-Energy STEM of Multilayers and Dopant Profiles
Low-Energy STEM of Multilayers and Dopant Profiles
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多层膜和掺杂剂分布的低能 STEM
DOI：
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发表时间：
2005
影响因子：
2.8
通讯作者：
V. Morandi
中科院分区：
文献类型：
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作者：
P. Merli;V. Morandi
一个传统的扫描电子显微镜配备了一个LaB 6源已被修改为在扫描透射模式下操作。已经考虑了两种检测策略，一种基于直接收集透射电子，另一种基于收集由透射电子的转换产生的二次电子。主要研究了两种类型的样品：半导体多层膜和注入As的Si中的掺杂分布。结果表明，对比度服从质量-厚度对比度规则，而分辨率总是由探头尺寸决定，与样品厚度和光束展宽无关。检测策略可能会影响图像的亮场（亮区域看起来更亮）或暗场（重区域看起来更亮）外观。使用透射电子的直接收集，可以从透射电子的角分布及其收集角推导出对比度。当收集二次电子来解释图像对比度时，还需要考虑二次产率对透射电子入射角的依赖性。
A conventional scanning electron microscope equipped with a LaB6 source has been modified to operate in a scanning transmission mode. Two detection strategies have been considered, one based on the direct collection of transmitted electrons, the other on the collection of secondary electrons resulting from the conversion of the transmitted ones. Two types of specimens have been mainly investigated: semiconductor multilayers and dopant profiles in As-implanted Si. The results show that the contrast obeys the rules of mass–thickness contrast whereas the resolution is always defined by the probe size independently of specimen thickness and beam broadening. The detection strategy may affect the bright field (light regions look brighter) or dark field (heavy regions look brighter) appearance of the image. Using a direct collection of the transmitted electrons, the contrast can be deduced from the angular distribution of transmitted electrons and their collection angles. When collecting the secondary electrons to explain the image contrast, it is also necessary to take into account the secondary yield dependence on the incidence angle of the transmitted electrons.