Through-focus scanning optical microscopy (TSOM) is a new metrology method that achieves 3D nanoscale measurement sensitivity using conventional optical microscopes; measurement sensitivities are comparable to what is typical when using scatterometry, scanning electron microscopy (SEM), and atomic force microscopy (AFM). TSOM can be used in both reflection and transmission modes and is applicable to a variety of target materials and shapes. Nanometrology applications that have been demonstrated by experiments or simulations include defect analysis, inspection and process control; critical dimension, photomask, overlay, nanoparticle, thin film, and 3D interconnect metrologies; line-edge roughness measurements; and nanoscale movements of parts in MEMS/NEMS. Industries that could benefit include semiconductor, data storage, photonics, biotechnology, and nanomanufacturing. TSOM is relatively simple and inexpensive, has a high throughput, and provides nanoscale sensitivity for 3D measurements with potentially significant savings and yield improvements in manufacturing.

Fabricating through-silicon vias (TSVs) is challenging, especially for conformally filled TSVs, often hampered by the seam line and void inside the TSVs. Stress-assisted void growth in TSVs has been studied by finite element stress modeling and x-ray computed tomography (XCT). Because x-ray imaging does not require TSVs to be physically cross-sectioned, the same TSV can be imaged before and after annealing. Using 8 keV laboratory-based XCT, voids formed during copper electroplating are observed in as-deposited samples and void growth is observed at the void location after annealing. We hypothesize that the mechanism generating voids is hydrostatic stress-assisted void growth. Stresses in a copper-filled TSV with a pre-existing void were simulated by finite element methods. The peaks of the hydrostatic stress and its gradient are shown to be around the edge of the void. Comparing simulated results and experimental data shows that void growth in TSVs is stress-assisted: v acancies diffuse and coalesce at the void as a result of the hydrostatic stress gradient

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This article is the third and final article in a series dedicated to reviewing each process step in crystalline silicon (c-Si) photovoltaic (PV) module manufacturing process: feedstock, crystallization and wafering, cell fabrication, and module manufacturing. The goal of these papers is to identify relevant metrology techniques that can be utilized to improve the quality and durability of the final product. The focus of this article is on the module manufacturing process. The c-Si PV module fabrication process can be divided into three primary areas; (1) stringing and tabbing, (2) lamination, and (3) integration of junction box and bypass diode(s). Each of these processing steps can impact the reliability and durability of PV modules in the field. The ultimate goal of this article is to identify appropriate metrology techniques and characterization methods that can be utilized within a module manufacturing facility to improve the reliability and durability of the final product. Additionally, a gap analysis is carried out to identify areas in need of further research and a discussion is provided that addresses new challenges for advanced materials and emerging technologies.