PhD - Leuven | More than two weeks ago
Metrology and materials characterization are critical components in the development of advanced nanoelectronics structures for both CMOS and more exotic applications. Within the family of characterization techniques, Raman spectroscopy is of particular interest due to its non-destructive character and exceptionally fast time-to-result. The technique is uniquely sensitive to mechanical stress, chemical composition, doping and crystallographic structure. However, regardless of the concept, state-of-the-art semiconductor devices are defined on length scales that are far beyond the optical diffraction limit. This prevents the applicability of classical Raman spectroscopy for nanoelectronics applications, as it relies on the scattering of light at visible wavelengths and hence is limited to spatial resolutions of the order of 1 µm. Through plasmonic coupling with ultra-sharp Scanning Probe Microscopy (SPM) tips, the strengths of both techniques are combined in what is known as Tip-Enhanced Raman Spectroscopy (TERS), translating the versatility of Raman spectroscopy into the SPM nanoscale resolution. This opens the path toward answering key questions for materials’ research like how currents and strain behave at nanoscale dimensions and how these parameters affect device performance. The technique has the potential to reveal non-uniformities in the material on nanometer length scales and elucidate on how these defects correlate with the electrical properties of the eventual device.
Despite the availability of a best-in-class setup, TERS remains an expert technique requiring extensive insight in both the SPM and Raman component, which the student will have the opportunity to develop. The objective is to come to a deep understanding of the laser-tip interaction, which will enable us to extract critical material parameters like mechanical stress, composition and doping from this non-standard Raman scattering configuration. The combination of the localized nature of the TERS experiment and the complexity of the advanced structures to be investigated (2D materials, scaled devices,...) sets a great metrology challenge. The ultimate goal is to cross-correlate the Raman results with information from the other available SPM modes (KPFM, MFM, SCM,...). Building on extensive in-house know-how on both the spectroscopy and SPM aspects of the technique, the PhD candidate will develop and optimize TERS measurement approaches and explore their interpretation for deep-subwavelength semiconductor structures. The unique and stimulating imec research environment and the availability of flagship metrology equipment will enable breakthrough scientific results.
Required background: Physics, Engineering
Type of work: 70% experimental, 30% interpretation and modelling
Supervisor: Ingrid De Wolf
Co-supervisor: Claudia Fleischmann
Daily advisor: Thomas Nuytten
The reference code for this position is 2021-005. Mention this reference code on your application form.