【正文】 obtained even from specimens of simple structure. In stereo observation, after a field of interest is photographed, the same field is photographed again with the specimen tilted from 5186。 彈性背散射電子：一般樣品表面原子核反彈回來可達數(shù)千至數(shù)萬 ev。 Retractable BSE detector in chamber Objective lens Secondary detector (ETD) BSE paths and detector locations Objective lens BSE from adjacent regions on flat sample SEM Compositional image Backscattered SEM image of an PbSn alloy showing contrast based on the atomic number. The brighter areas are Pbrich. 1 背散射電子的襯度原理及應用 背散射電子用于： 1）形貌分析 —— 來自樣品表層幾百 nm范圍 2）成分分析 —— 產(chǎn)額與原子序數(shù)有關 3）晶體結構分析 —— 基于通道花樣襯度 1． BE形貌襯度特點 1）用 BE進行形貌分析時，其分辨率遠比 SE像低。 E40， η 對 E十分敏感。 2）既進行成分分析又要進行形貌分析時，可采用對稱分布的檢測器收集信號（同一部位的 BE），然后計算機處理分別得到形貌信號和成分信號。 The generation region of backscattered electrons is larger than that of secondary electrons, namely, several tens of nm. Therefore, backscattered electrons give poorer spatial resolution than secondary electrons. But because they have a larger energy than secondary electrons, they are less influenced by chargeup and specimen contamination. Use of backscattered electron signals TOPO Xray (Si) Xray (Al) BEI SEI COMPO Specimen: Slug 20kV x1,100 The backscattered electron image is important also as a supplementary means for xray analysis. Influence of chargeup on image quality Specimen: Resist. Chargeup can be prevented by properly selecting the accelerating voltage. (a) kV x3,200 (a) 4 kV (b) 10 kV (b) kV x3,200 Specimen: Foreleg of vinegar fly. Chargeup can be reduced by using low accelerating voltage. Specimen damage by electron beam Specimen: Compound eye of fly. 5 kV x1,00 When a specimen area is irradiated with an electron probe for a long time at high magnification, it may be damaged as shown in (b). (b) (a) Contamination When the electron probe is irradiated on a specimen portion for a long time, its image may lose sharpness and bee dark. This is caused by the residual gas in the vicinity of the specimen being struck by the electron probe. This phenomenon is called specimen contamination. The conceivable residual gases in the specimen chamber, which cause contamination are: 1) Gas caused from the instrument itself. 2) Gas that specimens bring into the instrument 3) Gas that the specimen itself gives off. Specimen: ITO. A x18,000 photo taken after a longtime electron probe scanning at x36,000. As pared with the clear image of peripheral region, the middle region shows reduced contrast and lacks image sharpness. 5 kV x18,000 電子探針顯微分析 Xray Microanalysis Comparison of Energy Dispersive Spectroscopy [EDS]能譜儀 and Wavelength Dispersive Spectroscopy spectra [WDS]波譜儀 能譜儀成分分析的特點 : 優(yōu)點 : 1, 探測 X射線的效率高， ( 探頭與樣品近 ,不必通過分光晶體衍射 )能譜儀的靈敏度比波譜儀高一個數(shù)量級。 缺點 : 1，分辨率低于波譜儀。它是在電子光學和 X射線光譜學原理的基礎上發(fā)展起來的一種高效率分析儀器。 2, 可在同一時間內(nèi)對分析點內(nèi)所有元素 x射線光子的能量進行測定和計數(shù)，幾分鐘內(nèi)可得到定性分析結果 ,而波譜儀只能逐個逐個測量每種元素的特征波長。 EDS: 160eV WDS:5~10eV 2，只能測試 Z大于 11的元素 ,而波譜儀可測 Z從 4到 92間的所有元素。由此，可將樣品作用體積內(nèi)不同波長的 X射線分散并展示出來。 X射線聚焦方式有兩種： 1) Johann 型聚焦法：彎曲單晶的衍射晶面的曲率半徑為 2R。 定性分析 點分析 線分析 面分析 SEM Xray Maps of W, Ni and Cr 20 micron Maps