T. Kane, Z. Song, T. Su, IBM, Hopewell Junction, NY; H. S. Song, Samsung Electronics Co, Seoul, South Korea; J. Yu, Global Foundries Singapore, Singapore, Singapore

Summary: The scanning electron microscope (SEM) is a basic and imperative tool in any failure analysis Lab and it has been used extensively for imaging and analyzing the defects for semiconductor device failure analysis. In most cases, the secondary electron (SE) imaging can provide high quality image of a defect if the defect is on the surface. As the semiconductor device geometry continually shrinks and low K dielectrics was employed, there is an increasing trend of imaging the sample just after parallel polish without any etch to expose the layer of interest. In this case, the backscattered electron imaging, with good atomic number (Z) contrast and deep imaging field, looks better to image the embedded subtle defects during failure analysis in latest process technology than secondary electron imaging. It also has other advantages, such as, it can eliminate the risk of removing the subtle defect by dry or chemical etch to expose the defect for secondary electron imaging, and also keep the defect intact and well wrapped for follow up analysis like XTEM analysis. In this work, BSE imaging was employed to image some embedded subtle defects, which were not seen or not clear in SE image, in 32nm processes.