Integration of porous low dielectric constant materials constitutes a major roadblock in the reliable manufacturing of back end of the line (BEOL) wiring for the advanced technology nodes. The two ...main issues for Ultra low-k (ULK) materials are their low mechanical properties and high sensitivity to plasma induced damage (PID). We have developed a new class of bridged oxycarbosilane (OCS) type materials with unique stiffness, and a novel process to enable their integration. The Post Porosity Plasma Protection (P4) consists of refilling the pores of the fully cured porous ULK with an organic material prior to patterning, integrating the protected ULK and thermally removing the filler at the end of the process. We demonstrate the enormous potential of our integrated solution (materials at k≤2.2 and P4 process) on blanket films and its compatibility with integration of single damascene structures at relaxed ground rules.
A general route to organic-inorganic hybrids with nanophase morphologies has been elaborated with the objective of ultimately generating nanoporosity in organosilicates. Hyperbranched block ...copolymers prepared by either the sequential or concurrent polymerization of an ABC monomer (I3-(Im-caprolactone) 2-bromo-2-dimethylpropionate) with a BCD monomer (2-hydroxyethyl methacrylate) were used as the macromolecular templates. The two monomers, each polymerizing by different chemistries, for example ring-opening polymerization and atom transfer radical polymerization, bear initiating centres that are targeted for the functionality located on the accompanying monomer. Consequentially, a branched polymer is obtained which avoids the traditional multistep procedures. The branching density was altered simply by the addition of the appropriate AB (Im-caprolactone) and/or CD (methyl methacrylate) comonomers. These polymers were readily soluble initially in the organosilicate prepolymer (methyl silsesquioxane).
A few years ago, we developed at the IBM Almaden Research Center, the concept of introducing carbon in low-k materials in the form of bridging units between the silicon atoms and not as a pendant ...methyl group. Since then, this strategy has been widely adopted among the semi-conductor industry and the most advanced spin-on and PECVD ULK materials are now based on this model. This paper addresses the concept of designing ultra low-k bridged materials to achieve the best mechanical properties, to control the pore size and connectivity and to prevent plasma damage.
Integration challenges of porous ultra low-k (ULK) materials resulting from the ULKs' high sensitivity to process damage constitute a major roadblock to their implementation in back-end-of-the-line ...wiring structures for advanced technology nodes. The Post Porosity Plasma Protection strategy, which we introduced last year, enables to shield the ULKs' porosity during key integration steps. We report here on the feasibility of the protection across a wider range of dielectric constants and the advantages offered by our strategy during integration in terms of critical dimension integrity and electrical properties.
Plasma induced modification of porous SiCOH (OSG) ultra low-k (ULK) and extreme ultra low-k (eULK) dielectric materials during "resist" removal is investigated. Angular resolved X-ray photoelectron ...spectroscopy (ARXPS) was applied to specially-designed 200mm test structures exposed to a variety of plasma ash processing conditions. Characterization of the plasma for each of these applied ash conditions was achieved via optical emission spectroscopy/actinometry and modeling. This data was used in conjunction with ARXPS analytical data to propose mechanisms for film modification as a function of critical plasma parameters such as reactive species densities and ion scattering. These trends/mechanisms were electrically tested on 200 and 300mm patterned wafers. These and other results are presented and discussed
The exceptional mechanical properties of polymer nanocomposites are achieved through intimate mixing of the polymer and inorganic phases, which leads to spatial confinement of the polymer phase. In ...this study we probe the mechanical and fracture properties of polymers in the extreme limits of molecular confinement, where a stiff inorganic phase confines the polymer chains to dimensions far smaller than their bulk radius of gyration. We show that polymers confined at molecular length scales dissipate energy through a confinement-induced molecular bridging mechanism that is distinct from existing entanglement-based theories of polymer deformation and fracture. We demonstrate that the toughening is controlled by the molecular size and the degree of confinement, but is ultimately limited by the strength of individual molecules.
Adsorption processes are ubiquitous in nature as well as of great technological importance for gas separation, purification, storage and thermally driven heat pumps. This has led to a strong interest ...in the fundamental mechanisms governing adsorption phenomena and their exploitation to tailor adsorption systems for specific applications. In particular, the adsorption of water on porous silica exhibits remarkable properties due to the strong polarity of the adsorbate and moderate hydrophilicity of the adsorbent. It is generally accepted that the adsorption of water vapor on porous silica depends upon the concentration of surface silanols and the pore size. In fact, materials with ordered mesopores and a well-defined pore size have been used as model systems to demonstrate that water adsorption occurs predominantly through capillary condensation. While the pore surface chemistry is modified to become more hydrophilic after filling of the pores in these materials, the overall shape of the water adsorption isotherm (Type V) is not significantly affected in subsequent adsorption measurements. The present contribution shows that conservation of the isotherm shape is a unique phenomenon related to ordered mesopores but doesn't apply to materials with a more complex pore structure. For materials with wider pore size distributions including micropores, a synergistic effect of surface hydroxylation and pore size leads to a dramatic change in the water adsorption isotherm after the first adsorption/desorption cycle. In fact, we demonstrate that the water cycling capacity at relative pressures below the onset of capillary condensation increases significantly in these systems. These results contribute to a fundamental understanding of water adsorption in complex systems and have important implications in applications such as adsorption heat pumps where a large water cycling capacity in a specific relative pressure window is required.
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•Water adsorption and wettability of micro- and mesoporous silica was investigated.•Micropore filling of silica calcined at 600 °C is suppressed due to its hydrophobic nature.•Instead, micropore and mesopore filling coincide as apparent capillary condensation.•Apparent capillary condensation hydroxylates the surface and increases hydrophilicity.•Isotherm shape is drastically changed for microporous compared to mesoporous silica.
Traumatic penetrating injuries to the back are uncommon in children. This type of injury presents many considerations for airway management to the anesthesiologist, including having to secure the ...airway in a prone position. Although there have been several reports about intubation in the prone position for adult patients in emergency conditions, such studies on pediatric patients are rare. We present the case of a male child with an impaled steel shaft connected to a toy car wheel in his lower back, requiring an emergent operation under general anesthesia. Due to resource limitations, the patient was intubated using an adult-sized video laryngoscope in the prone position. The patient remained stable during the operation and was discharged without complications. A postoperative discussion was held later to review the case and gain insights from the rest of the anesthesiology team. Prone intubation in pediatric patients can be safely accomplished using various techniques, depending on the urgency of the need, the availability of resources, and the knowledge and skills of the provider. The authors hope that their colleagues can learn from sharing this experience.
Polymer confinement is realized in hybrid nanocomposites where individual polymer molecules are confined by a nanoporous matrix to dimensions less than the molecular size of the polymer. Here it is ...shown that by functionalizing the interior pore surfaces of a nanoporous organosilicate matrix, the pores can be filled with polystyrene molecules to achieve extreme levels of molecular confinement not previously possible. This provides opportunities for unique thermal and mechanical properties. It is shown that pore surface functionalization markedly impacts the polymer mobility during polymer infiltration by affecting the polymer–pore surface interaction, addressing the challenge of filling high‐molecular‐weight polymer molecules into nanoscale‐confined spaces. This allows for achieving extreme levels of molecular confinement with the loss of interchain entanglement and extensive polymer elongation along the pore axis. The glass transition temperature of the polymer is suppressed compared to bulk polymer melt, and is significantly affected by the polymer–surface interaction, which changes the polymer segmental mobility. The polymer–surface interaction also affects the interfacial polymer–pore sliding shear stress during polymer pullout from the nanopores, markedly affecting the fracture resistance of the nanocomposite.
Molecular confinement of polymers by a nanoporous matrix is achieved in hybrid nanocomposites. The interaction of the confined polymer with the pore surface can be manipulated by surface chemical functionalization of the pores to significantly influence the polymer mobility and the nanocomposite thermal and mechanical properties, allowing achievement of extreme levels of molecular confinement not previously possible.
Molecularly confined polymer fillers in nanopores were found to give superior mechanical properties of polymer nanocomposites. In this work, we study the thermal conductivity of such nanocomposites ...and unveil the effect of polymer confinement on thermal conductivity. Using the time-domain thermoreflectance method, we measure the cross-plane thermal conductivity of polymer nanocomposites that consist of polystyrene fillers confined within a nanoporous organosilicate matrix. Compared to unconfined bulk polystyrene fillers, we find that pore-confined polystyrene fillers enhance the thermal conductivity of the polymer nanocomposites. This enhancement is attributed to the better aligned and less entangled chains in the confined phase, where chain–chain phonon scatterings are reduced. Our work provides essential insights into the thermal conductivity of polymer nanocomposites for multifunctional thermal and mechanical applications.
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