Imaging Dopant Interfaces in 5 nm-Node finFETs with STEM EBIC

Abstract

The transmission electron microscope (TEM) provides high-resolution image contrast related to the physical structure and composition of a sample. But, lacking sensitivity to local electronic properties, TEM is blind to device features in which very subtle physical changes give rise to substantial electronic changes, such as selective doping in silicon. Here we use scanning TEM electron beam-induced current (STEM EBIC) imaging to map electric field-related contrast arising from dopant interfaces in commercially available, 5 nm-node finFETs. We present a sample preparation approach in which the component is mechanically polished down to the first few metal layers before cross section extraction, which facilitates connection to multiple fins for STEM EBIC analysis. We also show that the EBIC contrast is consistent with the expected device layout for this component. We will discuss the practical challenges of sample preparation and image acquisition, as well as the prospects for higher throughput STEM EBIC analysis.