Bottom-up superconformal Au filling of trenches as tall as seventeen micrometers, with aspect ratios of 26, is demonstrated. Deposition is conducted in a near-neutral Na 3 Au(SO 3 ) 2 electrolyte containing a micromolar concentration of Bi 3+ , known to accelerate the Au deposition and provide void-free, bottom-up filling of smaller trenches. Electroanalytical and X-ray photoelectron spectroscopy (XPS) measurements show that a Bi surface species is responsible for the accelerated Au deposition. The adsorbed Bi has a profound effect on the morphological evolution of the surface at the concentration and potentials of interests, transitioning from the growth of isolated (111) oriented trigonal pyramidal features in its absence to the growth of smooth epitaxial deposits once the fractional coverage of Bi reaches 0.15 ± 0.02 (1σ). A non-linear dependence of Au deposition rate on Bi coverage gives rise to extended incubation prior to the onset of bottom-up feature filling. For higher transport conditions, shearing of the interface limits Bi coverage to a value of approximately 0.05 or less, which correlates with a small leakage or passive current for Au deposition. The unusual correlation of Bi coverage with hydrodynamics is consistent with the inception and localization of deposition to the most recessed, and thereby quiescent, bottom surface of the patterned trench arrays.

Structural fire engineering (SFE) is a relatively new interdisciplinary subject, which requires a comprehensive knowledge of heat transfer, fire dynamics and structural analysis. It is predominantly the community of structural engineers who currently carry out most of the structural fire engineering research and design work. The structural engineering curriculum in universities and colleges do not usually include courses in heat transfer and fire dynamics. In some institutions of higher education, there are graduate courses for fire resistant design which focus on the design approaches in codes. As a result, structural engineers who are responsible for structural fire safety and are competent to do their jobs by following the rules specified in prescriptive codes may find it difficult to move toward performance-based fire safety design which requires a deep understanding of both fire and heat. Fire safety engineers, on the other hand, are usually focused on fire development and smoke control, and may not be familiar with the heat transfer principles used in structural fire analysis, or structural failure analysis. This paper discusses the fundamental heat transfer principles in thermal calculation of structures in fire, which might serve as an educational guide for students, engineers and researchers. Insights on problems which are commonly ignored in performance based fire safety design are also presented.

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