Voids in copper lines are a common failure mechanism in the back end of line (BEOL) of integrated circuits manufacturing, affecting chip yield and reliability. As subsequent process nodes continue to shrink metal line dimensions, monitoring and control of these voids gain more and more importance . Currently, there is no quantitative in-line metrology technique that allows voids to be identified and measured. This work aims to develop a new method to do so, by combining scatterometry (also referred to as Optical Critical Dimension or Optical CD) and low-energy x-ray fluorescence (LE-XRF), as well as machine learning techniques. By combining the inputs from these tools in the form of hybrid metrology, as well as with the incorporation of machine learning methods, we create a new metric, referred to as <i>V<sub>xo</sub></i>, to characterize the quantity of void. Additionally, the results are compared with inline electrical test data, as higher amounts of voids were expected to increase the measured resistivity. This was not found to be the case, as the impact of the voids was much less of a factor than variation in the cross-sectional area of the lines.
Lithography faces an increasing number of challenges as errors in pattern overlay and placement become increasingly significant as scaling continues. The flexibility of removing a lithography step offers a significant advantage in fabrication as it has the potential to mitigate these errors. Furthermore, this strategy also relaxes design rules in semiconductor fabrication enabling concepts like self-alignment. The use of selective area atomic layer deposition with self-assembled monolayers that incorporate different side group functionalities was evaluated in the deposition of a sacrificial etch mask. Monolayers with weak supramolecular interactions between components (e.g. Van der Waals) were found to exhibit significant defectivity when depositing this material at and below 100nm feature sizes. The incorporation stronger supramolecular interacting groups in the monolayer design, such as hydrogen bonding units or pi-pi interactions, did not produce an added benefit over the weaker interacting components. However, incorporation of reactive moieties in the monolayer component enabled the subsequent reaction of a SAM surface generating a polymer at the surface and providing a more effective barrier, greatly reducing the number and types of defects observed in the selectively deposited ALD film. These reactive monolayers enabled the selective deposition of a film with critical dimensions as low as 15nm. The deposited film was then used as an effective barrier for standard isotropic etch chemistries, allowing the selective removal of a metal without degradation to the surrounding surface. This work enables selective area ALD as a technology by (1) the development of a material that dramatically reduces defectivity and (2) the demonstrated use of the selectively deposited film as an etch mask and its subsequent removal under mild conditions.