Modern computer microprocessor chips are marvels of engineering complexity. For the current 45 nm technology node, there may be nearly a billion transistors on a chip barely 1 cm2 and more than 10 000 m of wiring connecting and powering these devices distributed over 9-10 wiring levels. This represents quite an advance from the first INTEL 4004B microprocessor chip introduced in 1971 with 10 μm minimum dimensions and 2 300 transistors on the chip! It has been disclosed that advanced microprocessor chips at the 32 nm node will have more than 2 billion transistors.1 For instance, Figure 1 shows a sectional 3D image of a 90 nm IBM microprocessor, containing several hundred million integrated devices and 10 levels of interconnect wiring, designated as the back-end-of-the-line (BEOL). Since the invention of microprocessors, the number of active devices on a chip has been exponentially increasing, approximately doubling every two years. This trend was first described in 1965 by Gordon Moore,2 although the original discussion suggested doubling the number of devices every year, and the phenomenon became popularly known as Moore’s Law. This progress has proven remarkably resilient and has persisted for more than 50 years. The enabler that has permitted these advances is known as scaling, that is, the reduction of minimum device dimensions by lithographic advances (photoresists, tooling, and process integration optimization) by ∼30% for each device generation.3 It allowed more active devices to be incorporated in a given area and improved the operating characteristics of the individual transistors. It should be emphasized that the earlier improvements in chip performance were achieved with very few changes in the materials used in the construction of the chips themselves. The increase of performance with scaling * Corresponding author. E-mail: gdubois@us.ibm.com. † IBM Almaden Research Center. ‡ Stanford University. Willi Volksen received his B.S. in Chemistry (magna cum laude) from New Mexico Institute of Mining and Technology in 1972 and his Ph.D. in Chemistry/Polymer Science from the University of Massachusetts, Lowell, in 1975. He then joined the research group of Prof. Harry Gray/Dr. Alan Rembaum at the California Institute of Technology as a postdoctoral fellow and upon completion of the one-year appointment joined Dr. Rembaum at the Jet Propulsion Laboratory as a Senior Chemist in 1976. In 1977 Dr. Volksen joined the IBM Research Division at the IBM Almaden Research Center in San Jose, CA, where he is an active research staff member in the Advanced Materials Group of the Science and Technology function.

Low dielectric constant materials.

Zeolite membranes – Recent developments and progress

Hierarchical zeolites are a class of microporous catalysts and adsorbents that also contain mesopores, which allow for fast transport of bulky molecules and thereby enable improved performance in petrochemical and biomass processing. We used repetitive branching during one-step hydrothermal crystal growth to synthesize a new hierarchical zeolite made of orthogonally connected microporous nanosheets. The nanosheets are 2 nanometers thick and contain a network of 0.5-nanometer micropores. The house-of-cards arrangement of the nanosheets creates a permanent network of 2- to 7-nanometer mesopores, which, along with the high external surface area and reduced micropore diffusion length, account for higher reaction rates for bulky molecules relative to those of other mesoporous and conventional MFI zeolites.

http://science.sciencemag.org/content/sci/336/6089/1684.full.pdf

Synthesis of self-pillared zeolite nanosheets by repetitive branching.

Removal of heavy metals from water sources in the developing world using low-cost materials: A review.

Application of polymeric membranes for the adsorption of hazardous pollutants 
may lead to the development of next-generation reusable and portable water purification appliances. Membranes for membrane adsorption (MA) have the dual function of membrane filtration and adsorption to be very effective to remove trace amounts of pollutants such as cationic heavy metals, anionic phosphates and nitrates. In this review article, recent progresses in the development of MA membranes are surveyed. In addition, recent progresses in the development of advanced adsorbents such as nanoparticles are summarized, since they are potentially useful as fillers in the host membrane to enhance its performance. The future directions of R&D in this field are also shown in the conclusion section.

/pdf/removal-of-heavy-metals-and-pollutants-by-membrane-45fsmdm237.pdf

Removal of heavy metals and pollutants by membrane adsorption techniques

For all of the inorganic porous spin-on low-k films being developed today, a post-spin-on hydrophobic treatment is needed to reduce their moisture sensitivity. In the present work, we demonstrate that, for pure-silica-zeolite MFI spin-on low-k films, this extra hydrophobic treatment step can be potentially eliminated by using organic-functionalized pure-silica-zeolite MFI (OF PSZ MFI) nanoparticle suspension. Specifically, methyltrimethoxysilane was simply added to the synthesis solution for a PSZ MFI nanoparticle suspension that contains tetraethyl orthosilicate, tetrapropylammonium hydroxide, ethanol, and water. This approach takes advantage of the hydrophobic methyl groups in the zeolite nanocrystal framework as well as in amorphous silica in the low-k film. The improvement of the hydrophobicity of the spin-on film from this OF PSZ MFI nanoparticle suspension was demonstrated by the higher water contact angle of the film and less moisture sensitivity of the k value in an ambient atmosphere.

Organic-functionalized pure-silica-zeolite MFI low-k films

Following our previous works on pure-silica-zeolite (PSZ) MFI, in this study we explore PSZ MEL as a new option for low-k dielectric films. Our motivation has been to increase the microporosity of the spin-on films by moving to structures with a framework density (FD) lower than MFI. Nanoparticle PSZ MEL suspensions were synthesized by a two-stage method that allowed the yield of nanocrystals to be significantly enhanced, while the zeolite nanocrystals remain small. For the first time zeolite nanocrystals of about 50 nm were synthesized with a yield as high as 57%. Nanoparticle suspensions with different particle sizes and crystallinities were spun on silicon wafers to prepare continuous thin films. An ultralow-k value as low as 1.5 was obtained with MEL nanoparticle suspension of high relative crystallinity. The surface roughness of the PSZ MEL film with high relative crystallinity is greatly improved (Rrms ∼ 5.6 nm) compared to MFI films with high relative crystallinity (Rrms ∼ 12 nm).

Pure-silica-zeolite MEL low-k films from nanoparticle suspensions.

Nanoadsorbents in focus for the remediation of environmentally-related contaminants with rising toxicity concerns

The presence of heavy metals in water for human use or consumption represents a major risk to human health. It is therefore important to find materials to remove or minimise the concentration of these pollutants. The adsorption process for the removal of heavy metals is favoured by the use of low-cost materials that exhibit a porous structure and a high cation exchange capacity, such as zeolites and clays. On the other hand, chemical treatments, e.g., using acids and bases, can modify the properties of these materials, but more recently the application of surfactants has also shown to be successful for broadening their metal affinity and allowing the removal of diverse organic and inorganic pollutants from water. This paper reviews the application of modified zeolites and clays for the removal of heavy metals from water.

https://www.mdpi.com/2073-4441/9/4/235/pdf

Use of Surfactant-Modified Zeolites and Clays for the Removal of Heavy Metals from Water

The synthesis of organic-functionalized pure-silica-zeolites (PSZs) with MFI- and MEL-type structures for low-k applications prepared through a direct-synthesis method by adding a fluorinated silane to the synthesis solution is reported. The added fluorine functionality increases the hydrophobicity of the zeolites, which are characterized by scanning electron microscopy, X-ray diffraction, 29Si and 19F solid-state NMR spectroscopy, nitrogen adsorption, and thermogravimetric analysis. The functionalized zeolite powders have low water content and calcined spin-on films prepared from the functionalized nanoparticle suspensions exhibit higher water contact angles and lower k values (2.1 and 1.8 for the functionalized MFI- and MEL-type zeolites, respectively) than PSZ films. The use of a direct-synthesis method to decrease the moisture adsorption in the films eliminates the extra post-spin-on silylation steps that are traditionally used to render the zeolite films hydrophobic.

Dora I. Medina

Papers

Organic-functionalized pure-silica-zeolite MFI low-k films

Pure-silica-zeolite MEL low-k films from nanoparticle suspensions.

Nanoadsorbents in focus for the remediation of environmentally-related contaminants with rising toxicity concerns

Use of Surfactant-Modified Zeolites and Clays for the Removal of Heavy Metals from Water

Pure-Silica-Zeolite MFI and MEL Low-Dielectric-Constant Films with Fluoro-Organic Functionalization