聚焦离子束制备透射电子显微镜样品的两种厚度判断方法

透射电镜样品的厚度是透射电镜(TEM)表征中一个重要参数,快速准确地判断样品厚度是制备高质量样品的前提.本文通过使用聚焦离子束(FIB)制备了带有厚度梯度的透射电镜样品(Si、SrTiO3和LaAlO3),并提出两种制样过程中快速判断厚度的方法.第一种通过扫描电子显微镜(SEM)的衬度变化经验地判断样品的厚度;第二种是用FIB在样品边缘切一个斜边,通过SEM测量斜边侧面的宽度用几何方法推断样品的厚度.这两种方法都通过会聚束电子衍射(CBED)和电子能量损失谱(EELS)测量的厚度作为检验标准.对比认为,样品较薄时用SEM衬度测厚比较合适;样品比较厚时用几何方法测量比较直接.

Two methods of estimating sample thickness in FIB-TEM sample fabrication

The sample thickness is an important parameter in the characterization of transmission electron microscope (TEM).It is necessary to estimate the sample thickness quickly for making a high-quality sample.In this article,focused ion beam (FIB) was used to fabricate samples (including Si,SrTiO3 and LaAlO3) with thickness gradient and two methods of estimating sample thickness in FIB-TEM sample preparation were proposed.One method was estimating sample thickness by the contrast of scanning electron microscope (SEM) experientially.The other was cutting the sample's edge into a slope and deducing the thickness from the width of the slope in SEM images geometrically.Both convergent beam electron diffraction (CBED) and electron energy loss spectrometers (EELS) were used as a reference to verify the thickness.By comparison,the method of contrast was preferred to be used when the sample was thinner,while the geometrical method was preferred to be used when the sample was thicker.