Quantitative Measurement of Electric Fields in Microelectronics Devices by In-Situ Pixelated STEM

Abstract

The quantitative mapping of fields at nanometer scale is essential to understand the behavior of devices and improve their performance. Historically this has been performed by off-axis electron holography, as this technique is mature and provides robust quantitative measurements [1]. In recent years, improvements in hardware have made possible the recording of diffraction patterns during a scanning transmission electron microscopy (STEM) experiment, generating so-called 4D-STEM datasets. An increasing number of data processing methods, combined with specific acquisition settings, have led to a wide range of pixelated STEM techniques [2]. Here, we explore the differential phase contrast (DPC) technique [3], performed in a pixelated STEM configuration [4]. It allows for the quantitative measurement of electric fields based on the intensity displacements of the transmitted beam in the diffraction plane. We will show how DPC-like pixelated STEM measurements are affected by the configuration of the microscope and by data processing. The results will be compared to electron holography and simulations.

Measuring Spatially‐Resolved Potential Drops at Semiconductor Hetero‐Interfaces Using 4D‐STEM

“…In addition, the electron beam can be precessed before hitting the sample using a precession angle 𝜑, which is deprecessed below, leading to diffraction patterns with a reduced impact of dynamic diffraction. [26,34] Furthermore, by utilizing an energy filter we can improve the signal-to-noise ratio of the diffraction patterns by socalled zero-loss filtering. [35] To prove the applicability of the method, we use a model hetero-interface, namely the abrupt, lattice-matched GaAs/AlAs (001) interface.…”

“…[23] However, modern devices usually consist of more than one material and involve internal interfaces. At such heterointerfaces, the mean inner potential (MIP), which is the volume average of the atomic electrostatic potentials, [24][25][26] also changes across the interface. Therefore, an impinging electron beam feels a potential difference of ∆MIP accross the width of the interface ∆x, corresponding to an apparent electric field.…”