Nano-Scale Analysis Using Synchrotron-Radiation: Applications in the Semiconductor Industry
In semiconductor industry, process control and physical failure analysis were dominated by light and electron microscopy as well as surface analysis techniques including X-ray photoelectron spectroscopy (XPS) until the end of the last century. During the past decade, X-ray diffraction (XRD) and X-ray reflectivity (XRR) have been successfully applied in out-of-fab analytical labs. In addition to XRF and TXRF, some additional X-ray techniques – e.g. XRD, XRR and XPS - have been moved or are in the process to be moved from lab-based studies to in-line applications, using cleanroom compatible thin film characterization tools in wafer fabs. Lab-based smallangle X-ray scattering (SAXS) tools are applicable for pore size characterization in porous thin films. Advanced transmission X-ray microscopy (TXM) and X-ray computed tomography (XCT) systems with sub-100 nm resolution are currently being evaluated for their use in out-of-fab analytical labs. Apart from the on-site use of laboratory X-ray sources, synchrotron-radiation sources have been used in all fields of X-ray techniques: diffraction (SR-XRD), spectroscopy (SR-XPS, XAFS) and microscopy (SR-TXM/XCT). The high brightness and collimation of SR beams provide unique possibilities, e.g. for in-situ X-ray microdiffraction, photoelectron emission microscopy (PEEM) and in-situ TXM/XCT. In this paper, we demonstrate the high potential of the X-ray techniques for semiconductor industry, we describe potential implementations of these techniques for current and future applications, particularly for advanced process development and process monitoring, and we provide an outlook showing that we are living in a decade which is characterized by a breakthrough in the industrial application of Xray techniques. The application focus of this review is on the study of two types of nanostructures with typical dimensions less than 100 nm: artificial nanolayers and nanostructures caused by thin film deposition and patterning (litho/etch) processes as well as nanostructured materials, i. e. thin film materials with a “sub-structure” on sub-100 nm length scale.
Keywords: Synchrotron-Radiation, Semiconductor Industry, Nano-Scale, surface analysis techniques, X-ray photoelectron spectroscopy (XPS), thin film, X-ray computed tomography (XCT) systems
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