The fabrication of future interconnects in integrated circuits requires insulators with decreasing dielectric constants in order to maintain or improve the electrical performance of such devices. ...This is achieved through the introduction of air in the form of porosity. However, such porous materials suffer from two major drawbacks: lower mechanical properties and decreasing plasma resistance. In this paper we discuss the design of novel low-k materials, the structure/porosity effect on plasma damage and emerging solutions envisioned to mitigate these issues.
Mechanical properties of organic/ inorganic thin‐films prepared from bridged silicon precursors have been investigated. The Young's modulus follows a linear decay when porosity is introduced, a ...unique observation as compared to traditional organosilicates. Remarkably, in the dense state, fracture energies of 15–17 J.m–2 were measured, values that are larger than those for dense SiO2 (10 J.m–2), dispelling the common belief that all organosilicates are fragile and prone to fracture.
The intermolecular self‐crosslinking of functionalized macromolecules under ultra‐dilute conditions (see Figure) provides a versatile approach to the preparation of nanoparticles with very small ...sizes. The size and the chemical nature of the particles are easily controlled and the use of particles produced in this way in the generation of nanoporous thin films where the particles act as sacrificial porogens has been demonstrated.
Multilayer nanoporous films generated by a layer‐by‐layer spin‐on method are presented (see Figure). Precise control of the porosity of the individual layers that comprise the multilayer structure is ...demonstrated. Due to the simplicity of this fabrication method a wide range of potential applications in the areas of separation science, biotechnology, optics etc. are envisaged.
Nanoporous precursor structures (see Figure) created by unimicellular star polymers in organosilicate thermosets produce morphologically controlled porous materials for semiconductor chip ...applications.
The increasing sensitivity of porous low dielectric constant materials to process damage constitutes a major roadblock to their implementation in back-end-of-the-line (BEOL) wiring structures for ...advanced technology nodes. In the early 2000s and in anticipation to future low-k related integration challenges, the semiconductor industry started to investigate the possibility to repair or prevent this damage. It is remarkable that the most disruptive solutions proposed today are inspired from the work initiated more than 10 years ago. In this review we first describe the accepted mechanisms for plasma damage, followed by a quick summary of the methods used to quantify its extent on both blanket films and patterned structures. We then report on the past and current strategies developed to mitigate the plasma damage of porous, low-k materials during damascene integration processes.
A novel and general route to high Tg nanoporous organic thin films (see Figure) is described. The addition of reactive diluents to the thermosetting polyarylene resin creates a situation where the Tg ...exceeds the highest cure temperature. Hence, the sacrificial polymer used to generate the porosity can be decomposed in the glassy state, mitigating pore collapse.
The distinctive features of well‐defined, three‐dimensional macromolecules with topologies designed to enhance solubility and amplify end‐group functionality facilitated nanophase morphologies in ...mixtures with organosilicates and ultimately nanoporous organosilicate networks. Novel macromolecular architectures including dendritic and star‐shaped polymers and organic nanoparticles were prepared by a modular approach from several libraries of building blocks including various generations of dendritic initiators and dendrons, selectively placed to amplify functionality and/or arm number, coupled with living polymerization techniques. Mixtures of an organosilicate and the macromolecular template were deposited, cured, and the phase separation of the organic component, organized the vitrifying organosilicate into nanostructures. Removal of the sacrificial macromolecular template, also denoted as porogen, by thermolysis, yielded the desired nanoporous organosilicate, and the size scale of phase separation was strongly dependent on the chain topology. These materials were designed for use as interlayer, ultra‐low dielectric insulators for on‐chip applications with dielectric constant values as low as 1.5. The porogen design, chemistry and role of polymer architecture on hybrid and pore morphology will be emphasized.
Novel macromolecular architectures including dendritic and star‐shaped polymers and organic nanoparticles are synthesized based on a modular approach from several libraries of building blocks including functional dendrimers (see picture) and dendrons. One of the distinctive features of these well‐defined three‐dimensional macromolecules is to facilitate nanophase morphologies in mixtures with organosilicates and ultimately, upon thermolysis of the organic component, nanoporous organosilicate networks.
A unimolecular templating star‐shaped polymer with a compatibilizing outer corona, prepared by tandem ROP/ATRP procedures, was dispersed into a thermosetting organosilicate. The organic polymer was ...thermalized to leave behind its latent image in the matrix with a pore size that reflected the size of the polymer molecule, and provided the expected reduction in dielectric constant.
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