| AVS 58th Annual International Symposium and Exhibition | |
| Applied Surface Science Division | Tuesday Sessions |
| Session AS-TuA |
| Session: | Imaging and 3D Chemical Analysis - Part II |
| Presenter: | Wilfried Vandervorst, IMEC, Belgium |
| Correspondent: | Click to Email |
The trends in advanced semiconductor devices and technologies call for the ability to probe compositional and impurity distributions with a depth resolution approaching near-atomic resolution. At same time, quantitative interpretation is of utmost importance in particular in multilayer structures and at interfaces such as local silicide composition and phase, interfacial interactions high k metal gate, etc.. At the same time one must admit that the advent of nanoscale devices and three-dimensional structures like Finfets, nanowires necessitates techniques which provide 3D-resolution. In this paper we will discuss recent approaches in extracting local 2D, 3D information on dopant distributions, carrier distribution, defects in thin dielectrics, phase and composition analysis, detection of small voids in ultra narrow interconnect lines (> 15 nm) as well as in (large, > 50 micron!) Cu-interconnects (TSV’s).
For nanosale 1D and 2D characterization we presently rely on concepts such as EXLE-SIMS for ultra high depth resolution dopant profiling, SSRM for 2D- carrier analysis, C-AFM for dielectrics, (S)TEM (+ELNES, EDX, HAADF) for quantitative composition analysis. 3D-characterization represents a serious challenge and one must rely on concepts like the tomographic Atom Probe to extract 3D-composition analysis on the nm-scale or Tomographic TEM. We will show examples for both cases and address the issues of Atom Probe in particular as the latter, although very appealing, does contain many artifacts as well. The latter are linked to sample preparation, laser-tip interaction, and reconstruction artifacts as well as issues inherently linked to instrument performance (mass resolution, sensitivity,..) and underlying physics (linked to sample heterogeneity). For analysing 3D-dopant distributions in Finfets, this can be complemented with tomographic SSRM and SIMS through Fins.
For back-end applications, the detection voids in narrow Cu-lines (15-30 nm) can be done using EDX whereas their analysis in the very large Cu TSV’s requires sophisticated ion milling approaches (plasma based FIB, slcie and view) as excessive milling times and surface topography evolution (curtaining) can hide the required information.