This paper evaluates various optical metrology techniques for in-line control of the uniformity of 3D stacked structures. Advanced packaging technologies are rapidly evolving and 3D architectures require very well controlled process steps. Optical metrology techniques are now used for TSV but also for interconnect processing. In engineering mode, at the process implementation step, these techniques must be evaluated and then used to get uniform and repeatable processes. Among the 3D TSV Via middle process flow, the temporary bonding, wafer thinning and TSV reveal are key 3D process steps to get a uniform backside copper nail signature. High aspect ratio TSV are etched in Front End of the line and deep reactive ion etching systems generates radial non uniformities signatures. The wafer backside processing challenge consists in compensating this issue among the entire wafer surface. In this paper, all these process steps were characterized in order to quantify their specific intra-wafer dispersion signature .of the related key parameters. Cross correlation between the various intra-wafer process step signatures was then analyzed to verify the data set consistency and several process parameters analyzed to get a simple model. This model was then used to get a very uniform copper nail signature. For small diameter TSV and corresponding copper nails, a comparison has been done between full field OCT and confocal chromatic techniques.

Mueller matrix ellipsometry (MME) is a powerful metrology tool for nanomanufacturing. The application of MME necessitates electromagnetic computations for inverse problems of metrology determination in both the conventional optimization process and the recent neutral network approach. In this study, we present an efficient, rigorous coupled-wave analysis (RCWA) simulation of multilayer nanostructures to quantify reflected waves, enabling the fast simulation of the corresponding Mueller matrix. Wave propagations in the component layers are characterized by local scattering matrices (s-matrices), which are efficiently computed and integrated into the global s-matrix of the structures to describe the optical responses. The performance of our work is demonstrated through three-dimensional (3D) multilayer nanohole structures in the practical case of industrial Muller matrix measurements of optical diffusers. Another case of plasmonic biosensing is also used to validate our work in simulating full optical responses. The results show significant numerical improvements for the examples, demonstrating the gain in using the RCWA method to address the metrological studies of multilayer nanodevices.

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Critical Dimension (CD) control is essential in the semiconductor industry and becomes more challenging as photolithography limits keep getting pushed to reach technological nodes smaller than 10 nm. To ensure quality and control of the processes, it becomes necessary to explore new metrology techniques. In this sense, Critical Dimension Small-Angle X-ray Scattering (CDSAXS) has been identified as a potential candidate to determine the average shape of a line grating with a sub-nanometric precision. In this paper we benchmark the CDSAXS results to Optical Critical Dimension (OCD), Critical Dimension Scanning Electron Microscopy (CDSEM) and Transmission Electron Microscopy (TEM) measurements previously collected from industrial metrology tools at manufacturing line and in characterization laboratory. Emphasis is placed on the model used for CDSAXS and how to improve it. We discuss the differences between all these multi-scale and multi-physics techniques, and question our capacity to compare them.