High-κ Metal Gate MOSFETs: Impact of Extrinsic Process Condition on the Gate-Stack Quality—A Mobility Study

The effects of source/drain activation thermal budget and premetallization degas conditions on interfacial regrowth, carrier mobility, and defect densities are examined for SiO₂/HfO₂/TaN stacks. We observe a correlation between the mobility degradation and the interfacial re-growth possible with the thermal budget employed. The mobility degradation arises from an increase of defects, both within the interface layer (IL) and the high-kappa bulk, as detected by both pulsed current-voltage and charge-pumping measurements. Two junction activation processes have been applied: a conventional process (peak temperature of 1000 degC spike for t=1 s) and a Solid Phase Epitaxial Re-growth (SPER) (peak temperature of 650 degC for t=60 s). For 1000 degC spike-annealed films, where the highest SiO₂/IL defect density is observed, the consequent mobility degradation is explained by a transition region between HfO₂ and the IL which increases for high-temperature processing     

NBTI reliability of Ni FUSI/HfSiON gates: Effect of silicide phase

In this work, we investigate the negative bias temperature instability (NBTI), when Ni-rich (Ni₂Si and Ni₃₁Si₁₂) silicides are used as gate electrodes on HfSiON and compare them to Ni mono-silicide (NiSi). The study also investigates the influence of increased pre-metal deposition (PMD) temperature and decreased silicide thickness on NBTI.Our study demonstrates that, when initial threshold voltage differences are taken into account and comparisons are performed at the same oxide electric field, no significant differences in intrinsic NBTI behavior are found for devices with different Ni silicide gate electrodes. In addition, we performed an Arrhenius study showing similar activation energies, indicating that no favorable conditions for dielectric degradation are created by the increased amount of Ni.     

Effects of Al2O3 Dielectric Cap and Nitridation on Device Performance, Scalability, and Reliability for Advanced High- κ/Metal Gate pMOSFET Applications

A pFET threshold-voltage (Vt) reduction of about 200 mV is demonstrated by inserting a thin Al₂O₃ layer between the high-k dielectric and the TiN gate without noticeable degradation of other electrical properties. HfSiO_propcapped with 9 Aring of thin Al₂O₃obtains a low long-channel Vt of -0.37 V (the lowest among those with TiN gate), a high mobility of 59 cm² /V ldr s at 0.8 MV/cm (92% of universal value), a negligible equivalent- oxide-thickness (EOT) increase of 0.1 Aring (compared to the uncapped reference), and a low Vt instability of 4.8 mV at 7 MV/cm. It also passes the ten-year negative-bias-temperature-instability (NBTI) lifetime specification with a gate overdrive of -0.7 V. This indicates that thin Al₂O₃obtains caps are beneficial to the pFET applications. In contrast, nitrogen incorporation in the Al₂O₃-capped HfSiO_prop is not favorable because it increases the Vt by 50-140 mV, degrades the mobility by 10%-22%, increases the EOT by 0.5-0.8 Aring and the Vt instability by 5-13 mV, and reduces the NBTI lifetime by four to five orders of magnitude. Compared to postcap nitridation, high-k nitridation results in more severe degradation of these properties by incorporating nitrogen closer to the Si/SiO₂ interface.     

Second Law of Thermodynamics for Macroscopic Mechanics Coupled to Thermodynamic Degrees of Freedom

Starting from and only using classical Hamiltonian dynamics, we prove the maximum work principle in a system where macroscopic dynamical degrees of freedom are intrinsically coupled to microscopic degrees of freedom. Unlike in many of the standard and recent works on the second law, the macroscopic dynamics is not governed by an external action but undergoes the back reaction of the microscopic degrees of freedom. Our theorems cover such physical situations as impact between macroscopic bodies, thermodynamic machines, and molecular motors. Our work identifies and quantifies the physical limitations on the applicability of the second law for small systems.      

Deriving GENERIC from a Generalized Fluctuation Symmetry

Much of the structure of macroscopic evolution equations for relaxation to equilibrium can be derived from symmetries in the dynamical fluctuations around the most typical trajectory. For example, detailed balance as expressed in terms of the Lagrangian for the path-space action leads to gradient zero-cost flow. We expose a new such fluctuation symmetry that implies GENERIC, an extension of gradient flow where a Hamiltonian part is added to the dissipative term in such a way as to retain the free energy as Lyapunov function.     

Death and Resurrection of a Current by Disorder,Interaction or Periodic Driving

We present several models of biased transport on (random) comb-like structures and on percolating backbones, that allow full mathematical control. We show how power-law corrections in the distribution of trap sizes may lead to a discontinuity in the current-field characteristic: the current jumps to zero when the driving exceeds a threshold. The current may resurrect when the field is modulated in time, also discontinuously: a little shaking enables the current to jump up. Finally, exclusion between particles postpones or even prevents the current from dying, while attraction such as modeled in zero range processes may expedite it.     

The structure of 20 oximo-5α-pregnano-16-eno[3,4-C]-1′,2′,5′-oxadiazole (HS976)

The crystal and the molecular structure of the steroidal oxadiazole 20-oximo-5-pregnano-16-eno[3,4-C]-1,2,5-oxadiazole (C₂₁H₂₈N₂O₃) has been determined by direct methods, and refined to a finalR of 0.086 for 3100 observed reflections. The compound crystallizes in space groupP2₁, with cell dimensionsa=18.284(6),b=13.992(4),c=7.370(3)Å,=96.97(3)°;V=1885 ų,Z=4,D _x =1.27 g cm^–3, =1.5418 Å, (CuK =5.95 cm^–1. The two independent molecules are related by a pseudo twofold axis. Both molecules exhibit similar overall topography, rings A, B, C, and D adopting distorted sofa, chair, chair, and distorted envelope conformations, respectively.     

A Printable Photopolymerizable Thermosensitive p(HPMAm‐lactate)‐PEG Hydrogel for Tissue Engineering

Bioprinting is a new technology in regenerative medicine that allows the engineering of tissues by specific placement of cells in biomaterials. Importantly, the porosity and the relatively small dimensions of the fibers allow rapid diffusion of nutrients and metabolites. This technology requires the availability of hydrogels that ensure viability of encapsulated cells and have adequate mechanical properties for the preparation of structurally stable and well‐defined three‐dimensional constructs. The aim of this study is to evaluate the suitability of a biodegradable, photopolymerizable and thermosensitive A–B–A triblock copolymer hydrogel as a synthetic extracellular matrix for engineering tissues by means of three dimensional fiber deposition. The polymer is composed of poly(N‐(2‐hydroxypropyl)methacrylamide lactate) A‐blocks, partly derivatized with methacrylate groups, and hydrophilic poly(ethylene glycol) B‐blocks of a molecular weight of 10 kDa. Gels are obtained by thermal gelation and stabilized with additional chemical cross‐links by photopolymerization of the methacrylate groups coupled to the polymer. A power law dependence of the storage plateau modulus of the studied hydrogels on polymer concentration is observed for both thermally and chemically cross‐linked hydrogels. The hydrogels demonstrated mechanical characteristics similar to natural semi‐flexible polymers, including collagen. Moreover, the hydrogel shows suitable mechanical properties for bioprinting, allowing subsequent layer‐by‐layer deposition of gel fibers to form stable constructs up to at least 0.6 cm (height) with different patterns and strand spacing. The resulting constructs have reproducible vertical porosity and the ability to maintain separate localization of encapsulated fluorescent microspheres. Moreover, the constructs show an elastic modulus of 119 kPa (25 wt% polymer content) and a degradation time of approximately 190 days. Furthermore, high viability is observed for encapsulated chondrocytes after 1 and 3 days of culture. In summary, we conclude that the evaluated hydrogel is an interesting candidate for bioprinting applications.