Super-Resolution Optical Microscopy for Investigations of Defects in Semiconductor Device

Ripples scattering of sidewall in pattern devices is efficient and necessary for monitoring the semiconductor fabrication process. As a step towards improving the imaging quality in terms of scattering, an attempt has been made to use our recently reported method called Parametric Indirect Microscopic Imaging (PIMI) for the thin layer of pattern devices. The present study demonstrates that the resolving power of PIMI imaging for the sidewall of the pattern devices is better than that of the conventional microscopy techniques. The better resolving power of the present PIMI technique for imaging the sidewalls paves the (new) way for its industrial application for the inspection of the integrated semiconductor circuits. For the demonstration, PIMI images have been compared with AFM, which are very close agreement.

Fermi-level pinning-free WSe2 transistors via 2D van der Waals metal contacts and their complementary logic gate circuits

Precise control over the polarity of transistors is a key necessity for the construction of complementary metal–oxide–semiconductor circuits. However, the polarity control of two-dimensional (2D) transistors remains a challenge because of Fermi-level pinning resulting from disorders at metal–semiconductor interfaces. Here, we propose a strategy for clean van der Waals contacts, wherein a metallic 2D material, chlorine-doped SnSe2 (Cl–SnSe2), is used as the contact to provide an interface that is free of defects and Fermi-level pinning. Such clean contacts created via van der Waals integration of a 2D metal possess nearly ideal Schottky barrier heights, thus permitting polarity-controllable transistors. With the integration of 2D metallic Cl–SnSe2 as contacts, WSe2 transistors exhibit pronounced p-type characteristics, which are distinctly different from those of the devices with evaporated metal contacts, where n-type transport is observed. Finally, this ability to control the polarity enables the fabrication of functional logic gates and circuits, including inverter, NAND, and NOR.

Synthesis of crystalline and amorphous, particle-agglomerated 3-D nanostructures of Al and Si oxides by femtosecond laser and the prediction of these particle sizes

We report a single step technique of synthesizing particle-agglomerated, amorphous 3-D nanostructures of Al and Si oxides on powder-fused aluminosilicate ceramic plates and a simple novel method of wafer-foil ablation to fabricate crystalline nanostructures of Al and Si oxides at ambient conditions. We also propose a particle size prediction mechanism to regulate the size of vapor-condensed agglomerated nanoparticles in these structures. Size characterization studies performed on the agglomerated nanoparticles of fabricated 3-D structures showed that the size distributions vary with the fluence-to-threshold ratio. The variation in laser parameters leads to varying plume temperature, pressure, amount of supersaturation, nucleation rate, and the growth rate of particles in the plume. The novel wafer-foil ablation technique could promote the possibilities of fabricating oxide nanostructures with varying Al/Si ratio, and the crystallinity of these structures enhances possible applications. The fabricated nanostructures of Al and Si oxides could have great potentials to be used in the fabrication of low power-consuming complementary metal-oxide-semiconductor circuits and in Mn catalysts to enhance the efficiency of oxidation on ethylbenzene to acetophenone in the super-critical carbon dioxide.

Synthesis of crystalline and amorphous, particle-agglomerated 3-D nanostructures of Al and Si oxides by femtosecond laser and the prediction of these particle sizes

We report a single step technique of synthesizing particle-agglomerated, amorphous 3-D nanostructures of Al and Si oxides on powder-fused aluminosilicate ceramic plates and a simple novel method of wafer-foil ablation to fabricate crystalline nanostructures of Al and Si oxides at ambient conditions. We also propose a particle size prediction mechanism to regulate the size of vapor-condensed agglomerated nanoparticles in these structures. Size characterization studies performed on the agglomerated nanoparticles of fabricated 3-D structures showed that the size distributions vary with the fluence-to-threshold ratio. The variation in laser parameters leads to varying plume temperature, pressure, amount of supersaturation, nucleation rate, and the growth rate of particles in the plume. The novel wafer-foil ablation technique could promote the possibilities of fabricating oxide nanostructures with varying Al/Si ratio, and the crystallinity of these structures enhances possible applications. The fabricated nanostructures of Al and Si oxides could have great potentials to be used in the fabrication of low power-consuming complementary metal-oxide-semiconductor circuits and in Mn catalysts to enhance the efficiency of oxidation on ethylbenzene to acetophenone in the super-critical carbon dioxide.

Power-Delay Trade-Offs in Complementary Metal-Oxide Semiconductor Circuits Using Self and Optimum Bulk Control

Power dissipation and delay are the challenging issues in the design of VLSI circuits. This manuscript explores joint effect of Self-Bias transistors (SBTs) and Optimum Bulk Bias Technique (OBBT) on CMOS circuits. Earlier investigations on SBTs shows decrease in power dissipation of combinational as well as sequential circuits. We extend the analysis by studying the effect of OBBT on the static and dynamic power of CMOS circuits with SBTs coupled amid the pull-up/down network and the supply bars. Extensive SPICE simulations have been carried out in 0.18 μm technology. Results demonstrate that, a 73% drop in power in case of combinational circuits and 43% in case of sequential circuits can be accomplished by engaging OBBT in digital circuits. Trade-off between power and delay is also been presented.

Control of local stress in semiconductor silicon structures

Residual stress distribution in multilayer semiconductor structure is complicated and has a significant impact on device characteristics and yield, therefore their study is one of the actual tasks of modern device engineering. Purpose of the present work was to develop methods of estimation of actual residual stress distribution at the whole area of semiconductor structure and its elements as well.The estimation of residual stress distribution at the area of semiconductor structure was carried out on the basis of determining of local deformation of some areas of the structure by Makyoh topography. This method is based on consequent measurements of intensity of Makyoh image elements of the structure along the chosen direction followed by calculation of micro-geometrical profile and curvature radius.The estimation of residual stress of topological elements Si–SiO system was carried out by means of calculation of interference pictures obtained in a film-substrate gap after separating of film edge from substrate along open window perimeter.Analytical expressions relating semiconductor structure image characteristics with their deformation were developed by means of finite elements method. The expressions allow determining of local residual stress of chosen area of the structure. The examples of stress calculations in real structures are given.Proposed residual stress calculation methods allow to take into consideration character and curvature form of substrate, and also to estimate their magnitude in real topological elements of semiconductor circuits.

Electrochemical Probes of Microbial Community Behavior

Advances in next-generation sequencing technology along with decreasing costs now allow the microbial population, or microbiome, of a location to be determined relatively quickly. This research reveals that microbial communities are more diverse and complex than ever imagined. New and specialized instrumentation is required to investigate, with high spatial and temporal resolution, the dynamic biochemical environment that is created by microbes, which allows them to exist in every corner of the Earth. This review describes how electrochemical probes and techniques are being used and optimized to learn about microbial communities. Described approaches include voltammetry, electrochemical impedance spectroscopy, scanning electrochemical microscopy, separation techniques coupled with electrochemical detection, and arrays of complementary metal-oxide-semiconductor circuits. Microbial communities also interact with and influence their surroundings; therefore, the review also includes a discussion of how electrochemical probes optimized for microbial analysis are utilized in healthcare diagnostics and environmental monitoring applications.