Failure analysis studies in pseudomorphic SiGe channel p-MOSFET devices

• Published in: Microscopy of Semiconducting Materials pp. 413 - 416
• Main Authors: Chang, A C K, Ross, I M, Norris, D J, Cullis, A G, Tang, Y T, Cerrina, C, Evans, A G R
• Format: Book Chapter
• Language: English
• Published: Berlin, Heidelberg Springer Berlin Heidelberg
• Series: Springer Proceedings in Physics
• Subjects: Gate Length; High Resolution Transmission Electron Microscopy; High Resolution Transmission Electron Microscopy Image; SiGe Layer; Strained Layer
• ISBN: 354031914X; 9783540319146
• ISSN: 0930-8989
• DOI: 10.1007/3-540-31915-8_88

Two nominally identical series of pseudomorphic Si/Si0.64Ge0.36/Si p-channel MOSFET devices from adjacent locations of the same wafer were found to have radically different gate threshold voltages. Focused ion beam milling and transmission electron microscopy was employed to determine the structural differences between the devices from these two regions. Significant structural anomalies were found in the poorer performing devices consisting of fluctuations in the quality and thickness of the strained SiGe layer. These anomalies are believed to be the result of strain relaxation relating to the thickness of the strained layer relative to the critical thickness combined with temperature non-uniformities across the wafer during layer growth.