Tomographic metrology of 3D semiconductor nano-devices

Leuven - PhD
More than two weeks ago

You will develop new tomographic metrology concepts for the most advanced 3D nano-devices using state-of-the-art analysis systems.


Advanced semiconductor technology heavily relies on 3D nano-scale concepts such as finfets, nanosheets, nanowires – you name it. The performance of these devices is a tight interplay between its structure and chemical composition at the atomic level, i.e. a few misplaced dopant atoms can render a full device useless. Clearly, device fabrication and characterization, two processes that must go hand-in-hand, become increasingly complex and call for clever fabrication and 3D metrology solutions with close to atomic precision. Driven by this quest, two important microscopy concepts have emerged over the last years as key players, i.e. atom probe tomography (APT) and scanning transmission electron microscopy/tomography (STEM), enabling a scientist to visualize and count individual atoms in complex 3-dimensional nano-structures. APT provides high elemental selectivity and sensitivity but its quantitative and spatial accuracy is strongly degraded in heterogeneous systems. On the other end, STEM and X-ray (EDS) tomography have better spatial accuracy but lower elemental sensitivity. Ultimately, the hybridization of both concepts shows great potential for real, atomic-scale tomography as it would overcome these limitations. Both APT and STEM/EDS-tomography require similar sample preparation so that in principle samples can easily be transferred between the analysis systems. Merging the information deduced by the different techniques from the same sample then allows to combine their benefits and strengths, and hence boost the insight on the structural/chemical properties of the analyzed device.

You will have the opportunity to work with imec's state-of-the-art analysis equipment for atom probe tomography and transmission electron microscopy on materials and structures for the development of the future semiconductor 3D device technologies.  The research plan will concentrate on :

  • Further optimizing the hybrid STEM-EDS-APT analysis work flow and the sample preparation involved.
  • Analyzing 3D device structures after different process steps with a combination of STEM and EDS tomography and correlating with APT.
  • Developing procedures for merging the structural and chemical information obtained by the different techniques acquired on these samples.
  • Understanding the physics that lead to artifacts in the APT spatial reconstruction and optimizing the reconstruction procedures.
  • Improving the chemical quantification by APT by cross-correlation with EDS.

Internal and external reporting, and publishing of results in leading scientific journals and conferences.

Required background: Master physics/chemistry/materials science/nanotechnology

Type of work: 75% Experimental, 25% Theory

Supervisor: Wilfried Vandervorst

Daily advisor: Claudia Fleischmann

The reference code for this position is 1812-04. Mention this reference code on your application form.


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