Enabling the future of computer chips – Atomic force microscopy for inline metrology of next generation silicon devices (C4-MPS-Hobbs)

The continued growth in computer power that fuels the IT and AI revolutions is enabled by ever shrinking device sizes in silicon chips – Moore’s Law. This has recently led to a switch in the process of device fabrication from purely in-surface-plane material patterning, to layered structures, allowing feature sizes to decrease to the nanometre scale. At the same time in-plane patterning is driven ever smaller, down to 10 nanometres and less requiring control and measurements at sub-nanometre level. Combined, these length scales are testing the capability of existing measurement instruments, while the continuous cycle of measure, adjust, measure is a critical part of the process of constructing top-end devices (such as those required for AI). New technology and improved fundamental understanding is required.

This PhD project is focused on the development of the “measuring” technology, working with the industry leading UK semiconductor metrology company Infinitesima Ltd. Infinitesima has an atomic force microscopy (AFM) based technology that is being used for in-line quality control in cutting edge silicon devices. However, to meet the challenges posed by next-generation devices requires a better understanding of how the microscope actually works, and how it can be adapted to image the most challenging samples. The project will have two aspects, the balance between the two being determined by the preferences of the successful candidate as the PhD progresses.

One aim of the project will be to construct a model of how the very high aspect ratio tips required for imaging these devices, combined with the flexible cantilever that is an integral part of any AFM, behave in the presence of the forces found at the surface of the complex and highly convoluted devices. This will involve a combination of simulation and computation with experiments to test the models that are produced.

A second aim is to develop approaches for determining the structure within the vertical walls of the narrow trenches formed during device fabrication. This is an outstanding problem for chip manufacturers such as Intel, and one where we have the potential to make significant breakthroughs.

The project is jointly supervised by Prof Jamie Hobbs who has expertise in atomic force microscopy instrumentation and application (see Hobbs Lab for further details) and Prof Nigel Clarke who is a leading theoretical physicist. It is supported by Infinitesima Ltd through an EPSRC Collaborative Award. For further details please contact Jamie.Hobbs@sheffield.ac.uk.

Interested candidates are strongly encouraged to contact the project supervisors to discuss your interest in and suitability for the project prior to submitting your application.