Jai Ganesh Kameswaran: The Development and Implementation of a Novel Electron Diffraction Technique

Jai Ganesh Kameswaran is a fourth-year Ph.D. student working on a new electron diffraction technique under the supervision of Dr. Paulo Ferreira.

The scaling required to accommodate faster chip performance in electronic devices has necessitated the simultaneous reduction in the dimensions of copper interconnects (CIs) at the back end of the line. Such downscaling significantly affects the microstructure, thereby impacting resistivity, electromigration and stress migration reliability of CIs.

The focus of this research is on the development and implementation of a novel electron diffraction technique called precessed D-STEM, which will be used to investigate the evolution of texture and grain boundaries in downscaling nano-CIs and correlate local thermal stresses (arising during chip fabrication) with grain misorientations using finite element modeling. This technique allows for automated acquisition and indexing of diffraction data from grains as small as three nanometers and represents a major leap in the characterization of CIs for texture analysis, since Electron Back Scatter Diffraction (EBSD), currently the best available method for obtaining grain orientations in an automated fashion, is limited to approximately 30 nanometer grain size. When compared to existing electron diffraction techniques with similar spatial resolution, the precessed D-STEM technique also provides orders of magnitude improvement in time for pattern acquisition and analysis. In broad terms, this research is expected to provide crucial insight into microstructural dependence of reliability in CIs, thus allowing improved designs and processes for future interconnect technology.

Color coded orientation map from 120nm wide Cu lines.

Color codes for orientations are represented in the standard stereographic triangle.