Rapid mapping of digital integrated circuit logic gates via multi-spectral backside imaging

Modern semiconductor integrated circuits are increasingly fabricated at untrusted third party foundries. There now exist myriad security threats of malicious tampering at the hardware level and hence a clear and pressing need for new tools that enable rapid, robust and low-cost validation of circuit layouts. Optical backside imaging offers an attractive platform, but its limited resolution and throughput cannot cope with the nanoscale sizes of modern circuitry and the need to image over a large area. We propose and demonstrate a multi-spectral imaging approach to overcome these obstacles by identifying key circuit elements on the basis of their spectral response. This obviates the need to directly image the nanoscale components that define them, thereby relaxing resolution and spatial sampling requirements by 1 and 2 - 4 orders of magnitude respectively. Our results directly address critical security needs in the integrated circuit supply chain and highlight the potential of spectroscopic techniques to address fundamental resolution obstacles caused by the need to image ever shrinking feature sizes in semiconductor integrated circuits

Mid-infrared plasmonics for ultra-sensitive spectroscopy of biomolecular interactions

Thesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at [email protected]. Thank you.Mid-infrared (IR) absorption spectroscopy contrasts with numerous other biosensing methods in that it can directly probe molecular structure via bond specific vibrational modes and monitor structural changes even in the absence of any mass transfer. The technique is therefore a valuable tool for a wide range of applications critical for understanding basic biological function and important aspects of e.g. disease progression and treatment. Despite these attractive features, IR absorption spectroscopy is limited as its acquired signal depends on a molecular bonds intrinsic absorption cross-section and path length (via Beers Law). Sensitivity issues therefore restrict applications to a limited set of strong bands and/or relatively thick samples. Additionally, due to the strong absorption of water in theIR, measurements in fluid are cumbersome, requiring specialized equipment and extremely high analyte concentrations. Plasmonic nano-structures supporting resonances at mid-IR wavelengths offer an attractive means with which to overcome many of these limitations. In particular, plasmonic resonances result in strongly enhanced near-field intensities confined to the surface of metallic particles, which allow one to dramatically increase the absorption signal of molecules. This concept is termed SEIRA (Surface Enhanced Infrared Absorption Spectroscopy). This thesis focuses on leveraging IR-resonant plasmonic nanostructures to enable sensitive SEIRA measurements of molecular monolayers, even in aqueous solutions. In achieving this capability, we first develop methods for utilizing nano-particle interactions in engineered arrays and demonstrate their application to the optimal enhancement of protein absorption bands. We then demonstrate multi-band antennas, capable of simultaneously probing several vibrational bands. Thirdly, we present the first demonstrated use of engineered IR antennas for real-time, in-situ IR spectroscopy measurements on a series of protein and nano-particle binding interactions. By leveraging the far-field scattering properties of plasmonic nano-antennas in addition to the associated near-field enhancement and localization, our method enables a unique chip-based spectroscopy technology that is highly compatible with modern sample preparation and handling techniques. Finally, we present a theoretical treatment of the interaction between our engineered resonances and the natural molecular ones. Our general model correctly predicts detailed absorption spectra and a number of effects dependent the experimental setup and plasmonic antenna design

Infrared absorption spectroscopy

The present invention relates to an infrared absorption spectroscopy apparatus including an infrared transparent substrate comprising a first and second surface, an array of plasmonic nano-antennas arranged on the first surface of the infrared transparent substrate, a flow cell for holding a liquid to allow spectroscopy measurements in a liquid environment, the array of plasmonic nano-antennas being located inside the flow cell, an optical source providing an incident light probe signal incident on at least a part of the array of plasmonic nano-antennas via the second surface of the infrared transparent substrate, and an optical element to collect reflected light signal reflected by said part of the array of plasmonic nano-antennas

In-situ ultra-sensitive infrared absorption spectroscopy of biomolecule interactions in real time with plasmonic nanoantennas

Infrared absorption spectroscopy is a powerful biochemical analysis tool as it extracts detailed molecular structural information in a label-free fashion. Its molecular specificity renders the technique sensitive to the subtle conformational changes exhibited by proteins in response to a variety of stimuli. Yet, sensitivity limitations and the extremely strong absorption bands of liquid water severely limit infrared spectroscopy in performing kinetic measurements in biomolecules' native, aqueous environments. Here we demonstrate a plasmonic chip-based technology that overcomes these challenges, enabling the in-situ monitoring of protein and nanoparticle interactions at high sensitivity in real time, even allowing the observation of minute volumes of water displacement during binding events. Our approach leverages the plasmonic enhancement of absorption bands in conjunction with a non-classical form of internal reflection. These features not only expand the reach of infrared spectroscopy to a new class of biological interactions but also additionally enable a unique chip-based technology

Multi-Band Surface Enhanced Infrared Absorption Spectroscopy of Molecular Monolayers

We develop concepts for engineering multi-resonant infrared plasmonic antennas. We utilize these antennas in conjunction with a perfect absorber geometry to simultaneously enhance mid-infrared vibrational resonances separated by 3 mu m in in monolayer polymer and biomolecule samples. (C) 2013 Optical Society of Americ

Engineering mid-infrared nanoantennas for surface enhanced infrared absorption spectroscopy

Mid-infrared absorption spectroscopy is a powerful tool for optically probing the molecular structure of biological samples. However, using conventional approaches, IR measurements on small quantities of molecules are extremely challenging due to sensitivity limitations. The strong IR absorption of liquid water presents additional obstacles to performing measurements in biomolecules' native, aqueous environments. In this review we discuss the application of engineered plasmonic nanoantennas to overcoming these challenges. We provide overviews and highlight the key concepts of our recent work in designing infrared antennas and applying them to enhance the absorption of minute quantities of biomolecules as well as new fabrication methods for their high throughput and low-cost manufacturing

Dual-Band Perfect Absorber for Multispectral Plasmon-Enhanced Infrared Spectroscopy

Metamaterial-based perfect absorbers utilize intrinsic loss, with the aid of appropriate structural design, to achieve near unity absorption at a certain wavelength. For most of the reported absorbers, the absorption occurs only at a single wavelength where plasmon resonances are excited in the nanostructures. Here we introduce a dual-band perfect absorber based on a gold nanocross structure. Two bands of maximum absorption of 94% are experimentally accomplished by breaking the symmetry of the cross structure. Furthermore, we demonstrate the two bands can be readily tuned throughout the mid-infrared with their associated resonances giving rise to large near-field enhancements. These features are ideal for multiband surface-enhanced infrared spectroscopy applications. We experimentally demonstrate this application by simultaneously detecting two molecular vibrational modes of a 4 nm thick polymer film utilizing our proposed absorber. Furthermore, in response to variations in the interaction strength between the plasmonic and molecular dipoles, we observe an anticrossing behavior and modification in the spectral line shape of the molecular absorption peak, which are characteristic of the coupling between the two modes

Surface Excitation of Hybridized Plasmons In Metallic Nanocavities

We experimentally demonstrate surface excitation of hybridized plasmons in metallic nanocavities. We developed a quasi-static model connecting this observation to plasmonic antenna behavior for extraordinary light transmission effect