The ever-ongoing downscaling of semiconductor technology has led to a paradigm shift from planar to 3D devices. Industry has already started moving towards 3D architectures such as FinFETS, nanosheets and nanowires because they offer better electrostatic control and reduced power dissipation . The performance of these devices is now tailored by the structure and chemical composition at the atomic level, i.e. just a few misplaced dopant atoms can make the difference. Device fabrication has therefore never been so dependent on accurate characterization and this will only become more important as tomorrows materials and devices become increasingly complex with the new materials and ingenious fabrication processes that continue to unfold. Thus, having 3D metrology with close to atomic precision is not only a dream - it is a requirement!
Driven by this quest, atom probe tomography (APT) has emerged as the promised solution. In a nutshell, APT is based on the concept of controlled ionization and removal of atoms from the surface of a very sharp needle by applying ultra-short (fsec) voltage or laser pulses. Through the ions’ flight time towards the detection system, we can identify the elements present in the needle. By collecting the ions on a 2D detector, a full 3D reconstruction of the sample/devices composition with sub-nm resolution is expected. All the world’s major semiconductor manufacturers are looking at, and competing, to implement APT to fulfill their need for a 3D metrology. Here at imec we are working with our semiconductor partners to make this happen.
Although APT offers promise, it is still in its infancy for 3D semiconductor metrology. It has been shown to be sensitive to several artefacts in the analysis of complex, heterogenous 3D structures. The challenge is the underlying physics which includes the field evaporation of mixed materials and the tip-laser interaction, all of which may lead to quantification errors and a loss in spatial accuracy. Our goal at imec is to remain at the forefront of metrology research and development. This PhD will therefore allow the candidate to work with imec’s APT experts and its state-of-the-art equipment in conjunction with our semiconductor partners, not only for the development of a 3D metrology revolution (APT), but applying it to the materials and structures of tomorrows 3D devices. In order to enhance our understanding of the fundamental science behind APT, the PhD candidate will have the possibility to explore a vast playground of experimental work (APT sample preparation and data acquisition), data analysis (3D reconstruction...) and physical modelling (theory, simulation...). The limit: how far do you want to push your PhD and this technology. For further and more detailed information please don’t hesitate to contact us on the 3D metrology revolution.