PhD - Leuven | More than two weeks ago
The shrinking dimensions of nanoelectronic structures towards the sub-10 nm domain increasingly complicates the detection and visualization of failures and defects in fabricated devices. As even subtle defects can have a major impact on the functionality and reliability of devices and interconnections, the detection and analysis of these defects and their root cause is of high importance for the development of reliable manufacturing processes of such nano devices.
For current technology nodes, this analysis is commonly done in industry by visual inspection using a dual (electron/ion) beam system. Many defects, especially electrical defects, remain however invisible because the defect dimensions are beyond the imaging resolution of the involved high-resolution scanning electron microscope (SEM).
An attractive solution for this is to add in-situ electrical nanoprobing to such a system. This allows to apply failure analysis techniques such as electron beam induced current (EBIC), electron beam absorbed current (EBAC), resistive current imaging (RCI), active voltage contrast (aVC), etc. These techniques can be used to detect and visualize grain boundaries and defects such as dislocations, and are also able to pinpoint open and short connections, resistive defects, junction issues, etc.
Although these techniques are well known to work on 100 nm sized devices and larger, applying them to sub-10 nm node devices is becoming increasingly difficult because of nanoprobing integration issues affecting the obtainable resolution, low probe tip sharpness, drift/stability problems, etc.
The aim of his PhD is to study the applicability of nanoprobing on sub-10 nm devices and exploit new applications of this combined electrical probing and dual-beam inspection/preparation.
Several major obstacles must be overcome to enable nanoprobing on such small devices inside a SEM system: The probe tips must be positioned with (sub)nanometer accuracy while remaining in this position stable over time and being vibration insensitive. High electrically conductive, hard and ultra-sharp (≤1 nm) probe tips are needed to establish a reliable electrical contact between probe and device. Innovative inspections and probing concepts are required to achieve high SEM resolution while actively probing the device under investigation. Therefore, these factors will be studied in detail during this PhD research by performing dedicated experiments on sub-10 nm node structures and devices in different SEM systems and developing solutions (nanomanipulator, probe tips, measurements) to overcome the limitations of the prior art.
The main focus of this PhD is to fundamentally explore and perform nanoprobing analysis of novel nanoscale devices (e.g. 3D-NAND, forksheet transistor, nanowire transistors) and materials (SiGe stacks, 2D materials, metal nanowires), to adapt the existing approaches for EBIC, RCI, EBAC, and aVC for sub-10 nm modes and to establish new probing concepts and develop new know-how by combining a high-end dual-beam system with a state-of-the-art nanoprobe system.
Required background: Engineering Science or Physics
Type of work: 20% literature and technological study, 80% experimental
Supervisor: Ingrid De Wolf
Daily advisor: Kristof J.P. Jacobs
The reference code for this position is 2021-003. Mention this reference code on your application form.