In this work, we have designed copper chemical mechanical planarization (CMP) experiments to investigate the effect of slurry components on the planarization performance of copper wafer in the ...presence of two different surfactants including ammonium dodecyl sulfate (ADS) and fatty alcohol polyoxyethylene ether (AEO). Copper CMP was performed at pH10.5 using hydrogen peroxide (H2O2), silica, benzotriazole (BTA), and FA/O II (a unique alkaline macromolecular organic chelating agent with high activation energy) as an oxidizer, an abrasive, a corrosion inhibitor and a complexing agent, respectively. As hydrogen peroxide is added in the copper slurry, the material removal rate (MRR) increases rapidly and then decreases slowly as a function of the concentration of H2O2. The within-wafer non-uniformity (WIWNU) declines and the surface roughness decreases first and then ascends with the increase of the H2O2 concentration. The addition of BTA has a large effect on the MRR, WIWNU and copper surface roughness. The MRR decreases to approach a minimum as a function of the BTA concentration. While the copper surface WIWNU fluctuates and the surface roughness increases with increasing the amount of BTA. As FA/O II is chosen to be a complexing agent, the MRR increases prominently and the WIWNU decreases with the increase of the FA/O II concentration. The surface roughness also decreases indicating that the addition of FA/O II can effectively improve the surface planarization performance in the present copper CMP experiments. The mechanism of the corresponding experimental results is also elucidated and discussed. All the results show that the copper surface planarization performance could be strictly controlled by proper configuration of the slurry components and an optimal choice of the concentrations of the constituents can obtain a high removal rate, low WIWNU and small surface roughness of the copper wafer in alkaline slurries.
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•Influence of slurry components on Cu CMP performance is studied in alkaline media.•The H2O2 concentration has a large effect on the copper surface planarity in CMP.•BTA combined with AEO and ADS is good for improving the surface planarization.•MRR increases with improved WIWNU and surface roughness as FA/O II increases.•Good surface planarity is obtained by proper configuration of slurry components.
Bio-macromolecules have potential applications in cancer treatment due to their high selectivity and efficiency in hitting therapeutic targets. However, poor cell membrane permeability has limited ...their broad-spectrum application in cancer treatment. The current study developed highly internalizable anti-c-MET antibody Fab fusion proteins with intracellular epitope peptide chimera to achieve the dual intervention from the extracellular to intracellular targets in tumor therapy. In vitro experiments demonstrated that the fusion proteins could interfere with the disease-associated intracellular signaling pathways and inhibit the uncontrolled proliferation of tumor cells. Importantly, investigation of the underlying mechanism revealed that these protein chimeras could induce vacuolation in treated cells, thus interfering with the normal extension and arrangement of microtubules as well as the mitosis, leading to the induction of methuosis-mediated cell death. Furthermore, in vivo tumor models indicated that certain doses of fusion proteins could inhibit the A549 xenograft tumors in NOD SCID mice. This study thus provides new ideas for the intracellular delivery of bio-macromolecules and the dual intervention against tumor cell signaling pathways.
We present a density functional theory approach to investigate the thermodynamics of ice nucleation in supercooled water. Within the theoretical framework, the free-energy functional is constructed ...by the direct correlation function of oxygen-oxygen of the equilibrium water, and the function is derived from the reference interaction site model in consideration of the interactions of hydrogen-hydrogen, hydrogen-oxygen, and oxygen-oxygen. The equilibrium properties, including vapor-liquid and liquid-solid phase equilibria, local structure of hexagonal ice crystal, and interfacial structure and tension of water-ice are calculated in advance to examine the basis for the theory. The predicted phase equilibria and the water-ice surface tension are in good agreement with the experimental data. In particular, the critical nucleus radius and free-energy barrier during ice nucleation are predicted. The critical radius is similar to the simulation value, suggesting that the current theoretical approach is suitable in describing the thermodynamic properties of ice crystallization.
The role of non-ionic surfactant concentration in the planarization performance of copper wafer is investigated. The basic components of the slurry contain H
2
O
2
, a mixture of benzotriazole (BTA) ...and ammonium dodecyl sulfate (ADS), FA/O II (macromolecular organic complexing agent), and silica. The static performance of the alkaline slurry including the surface tension, viscosity, particle size distribution and zeta potentials is analyzed. The effect of AEO on material removal rate (MRR) profiles, within-wafer non-uniformity (WIWNU) and surface roughness is also discussed. The AEO in combination with a small amount of BTA and ADS has a large effect on the stability of abrasives, MRR, WIWNU and surface roughness. A new MRR model is proposed to elucidate the polishing mechanism, revealing that the inhibition properties of AEO can be characterized through the corrosion inhibition efficiency and adsorption behavior. An optimal choice of the AEO concentration can achieve a good stability of the slurry, high MRR, low WIWNU and planar surface. The surfactant concentration ranging from 0.1 wt% to 0.5 wt% would contribute to acquiring a good surface planarization performance. Therefore, this work provides a comprehensive understanding of the effect of AEO concentration on the surface planarity of copper CMP in alkaline slurries.
In this work, a new feature-scale model is proposed for investigating the interaction between the wafer pattern and individual pad asperities in the process of chemical mechanical planarization ...(CMP). Based on the contact mechanics equation and the modified Greenwood–Williamson (GW) model which captures the evolution of feature curvature and the modification of the pad asperity height distribution, the discrete convolution and fast Fourier transform (DC-FFT) technique is adopted and combined with the Picard iteration method to calculate the direct contact pressure distribution between the wafer surface and the polishing pad. The computed pressure is then used to determine the local removal rate of the underlying patterns and predict the evolution of the wafer surface profile. Furthermore, the method is extended to capture the metal dishing as the feature size changes. It is shown that the present model can avoid the false simulated results produced by directly applying the original GW model for CMP when the feature size approaches zero. Otherwise, the calculated surface profile and dishing values of pattern geometries are in good agreement with the experimental data. Therefore, this model can not only be used to simulate the evolution of the wafer surface for global planarization at lower technology nodes, but can also be applied to provide some basic design rules for improving the process parameters and reducing the time and cost for developing new architectures.
Hematoporphyrin monomethyl ether (HMME) is a novel and promising porphyrin-related photosensitizer for photodynamic therapy (PDT). HMME-PDT-induced cell death and its mechanisms were investigated in ...HeLa cells. We demonstrated that HMME-PDT could induce cell death through both necrosis and apoptosis. Sodium azide (the singlet oxygen quencher) or
d-mannitol (the hydroxyl radical scavenger) could protect HeLa cells from the apoptosis and necrosis induced by HMME-PDT, showing that reactive oxygen species (ROS), such as singlet oxygen and hydroxyl radical, played a decisive role in HMME-PDT-induced HeLa cells death. Sodium azide or
d-mannitol also inhibited HMME-PDT-mediated Ca
2+
i elevation. Cytochrome C (Cyto C) release from mitochondria into cytosol and Caspase-3 activation after HMME-PDT were inhibited by BAPTA/AM (an intracellular calcium chelator). These results demonstrated that ROS generated in HeLa cells by HMME-PDT-induced apoptosis may be through Ca
2+
i elevation which mediates Cyto C release and Caspase-3 activition and initiates the subsequent late stages of apoptosis.
In this work, the inhomogeneous polymer reference interaction site model (PRISM) integral equation theory is extended to investigate the microscopic structure of a new system of nanocomposites with ...polymer-grafted nanoparticles near solid surface. The chemical and morphologic details of polymers are described by a semiflexible chain model, which can be utilized to capture the intramolecular interactions between different segments. Based on the novel bridge functionals of different segments constructed from the corresponding chemical potentials, the modified hypernetted chain approximation is combined with the inhomogeneous PRISM equation to obtain the detailed density distributions of nanoparticle-polymer blends near substrate. The effects of particle volume fraction, nanoparticle size, attractive interaction strength between different segments and chain stiffness on the density profiles of single tethered polymer nanocomposites (PNCs) near surface are systematically investigated to capture the contribution of the packing and configurational entropies. The end effects of polymer chains and effects of solid wall confinement are also considered. It is found that the particle size and particle volume fraction play the most significant roles in the density profiles of the single tethered PNCs among the present investigated model parameters. The increase of the particle volume fraction leads to a monotonic increasing variation behavior of the density profiles of single tethered nanoparticles as the particle diameter is relatively small. With increasing the nanoparticle size, the intensity of the density profiles of nanoparticles decreases prominently. The detailed packing structure of polymer-nanoparticle blends is also influenced by the polymer chain stiffness and particle-monomer interactions, where these parameters of structure and chemistry can enable the density profiles of the single tethered PNCs to show similar variation trends. The present inhomogeneous PRISM theory can provide a detailed description of packing and conformational entropies on the density profiles of different segments in nanocomposites with polymer-grafted nanoparticles. It could also be easily extended to some real systems with more complicated architecture of polymer-grafted nanoparticles under confinement and anticipated to assist in developing some predictive approaches for design control of PNCs near substrate.
The inhomogeneous PRISM theory is extended to capture the structure of nanocomposites with polymer-grafted nanoparticles near solid surface. Display omitted
•Structure of PNCs with grafts near substrate is investigated by PRISM theory.•Increasing particle size decrease density profiles of PNCs near substrate.•Particle volume fraction plays a significant role in the structure of PNCs.•Increasing chain stiffness and attractive interaction decrease density profiles.•PRISM theory can describe the structure of PNCs with grafts near substrate.
•A new highly efficient 3-D transient thermal analysis model is constructed.•A new boundary treatment method is proposed to accelerate the efficiency.•A universal equivalent thermal model is proposed ...to enhance the flexibility.•The FOA is 3.74 times faster than Douglas-Gunn approach for matrix assignment.•The FOA-based solver is highly efficient and reliable for thermal analysis of CHI.
Thermal issue has significant effect on the reliability and performance of integrated circuits with the increase of integrated density, especially for 2.5-D and 3-D heterogeneous integration packaging systems. In this paper, a new highly efficient 3-D transient thermal distribution model has been constructed to capture the heat conduction behavior of multiple heat sources for chiplet heterogeneous integration (CHI) by improving the alternating direction implicit finite difference method (ADI-FDM). Firstly, a new floating optimization algorithm (FOA) of coefficient matrix assignment of heat conduction equation and a new boundary treatment utilizing virtual points are proposed to modify the ADI-FDM and improve the model efficiency of thermal analysis. Furthermore, a universal equivalent thermal conductivity model is also built up to describe the design features of through silicon via (TSV), bump and redistribution layer structures, which can enhance the flexibility of FDM-based thermal simulator. Compared with previous finite element analysis results, the present FOA-accelerated thermal model can not only obtain an accurate simulation result of temperature profile, but also give a simulation efficiency of 3.74 times faster than Douglas-Gunn approach for the coefficient matrix assignment. Finally, the effect of power consumption variation and the floorplaning effects of chiplets, TSVs and bumps on the temperature distribution are investigated in detail by utilizing the present FOA-based thermal solver. The simulated results of the present work demonstrate the viability and computational efficiency for temperature field optimization and indicate that the new proposed simulator is helpful in thermal analysis of packaging structures and can be adopted to assist in physical design optimization of 2.5-D CHI or 3-D heterogeneous stacked chips.
