Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation
Reference-free total reflection X-ray fluorescence analysis of semiconductor surfaces with synchrotron radiation
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DOI：
10.1021/ac071236p
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发表时间：
2007-10-15
影响因子：
7.4
通讯作者：
Ulm, Gerhard
中科院分区：
文献类型：
--
作者：
Beckhoff, Burkhard;Fliegauf, Rolf;Ulm, Gerhard
全反射x射线荧光（TXRF）分析是监测半导体表面最低水平污染的一种行之有效的方法。在软x射线范围内使用高通量同步辐射可以有效地激发晶圆表面上的轻元素。为了满足当前无损半导体分析的工业要求，德国物理技术协会（PTB）运营专用仪器，用于分析晶圆片以及200和300毫米硅晶圆表面的轻元素污染。该仪器也适用于掠入射x射线荧光分析和传统的能量色散x射线荧光分析，分别用于埋藏和表面纳米层结构。最突出的特点是高真空负载锁与设备前端模块相结合，特高压照射室与安装在八轴机械手上的静电吸盘相结合。在这里，在PTB实验室的电子存储环BESSY II上，通过平面光栅单色光束线提供的波动辐射单色辐射可以扫描200或300毫米晶圆的整个表面。该光束线具有较高的光谱纯度和0.078-1.86 keV范围内的高光子通量。此外，采用绝对校准的光电二极管和Si(U)探测器分别监测激发辐射功率和荧光辐射。此外，由于在BESSY II的特殊操作条件下允许大幅减少电子束电流，CCD记录的光束剖面记录了晶圆表面激发辐射的足迹。因此，完成了TXRF分析完全无参比定量的所有要求，并将在本工作中提出。本文还讨论了使用基于x射线管的桌面TXRF分析安排无参比定量的观点。
Total reflection X-ray fluorescence (TXRF) analysis is a well-established method to monitor lowest level contamination on semiconductor surfaces. Even light elements on a wafer surface can be excited effectively when using high-flux synchrotron radiation in the soft X-ray range. To meet current industrial requirements in nondestructive semiconductor analysis, the Physikalisch-Technische Bundesanstalt (PTB) operates dedicated instrumentation for analyzing light element contamination on wafer pieces as well as on 200- and 300-mm silicon wafer surfaces. This instrumentation is also suited for grazing incidence X-ray fluorescence analysis and conventional energy-dispersive X-ray fluorescence analysis of buried and surface nanolayered structures, respectively. The most prominent features are a high-vacuum load-lock combined with an equipment front end module and a UHV irradiation chamber with an electrostatic chuck mounted on an eight-axis manipulator. Here, the entire surface of a 200- or a 300-mm wafer can be scanned by monochromatized radiation provided by the plane grating monochromator beamline for undulator radiation in the PTB laboratory at the electron storage ring BESSY II. This beamline provides high spectral purity and high photon flux in the range of 0.078-1.86 keV. In addition, absolutely calibrated photodiodes and Si(U) detectors are used to monitor the exciting radiant power respectively the fluorescence radiation. Furthermore, the footprint of the excitation radiation at the wafer surface is wen-known due to beam profile recordings by a CCD during special operation conditions at BESSY II that allow for drastically reduced electron beam currents. Thus, all the requirements of completely reference-free quantitation of TXRF analysis are fulfilled and are to be presented in the present work. The perspectives to arrange for reference-free quantitation using X-ray tube-based, table-top TXRF analysis are also addressed.