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.

Carbon doped oxide dielectrics comprised of Si, C, O, and H (SiCOH) have been prepared by plasma enhanced chemical vapor deposition (PECVD) from mixtures of tetramethylcyclotetrasiloxane (TMCTS) and an organic precursor. The films have been analyzed by determining their elemental composition and by Fourier transform infrared spectroscopy with deconvolution of the absorption peaks. The analysis has shown that PECVD of TMCTS produces a highly crosslinked networked SiCOH film. Dissociation of TMCTS appears to dominate the deposition chemistry as evidenced by the multitude of bonding environments and formation of linear chains and branches. Extensive crosslinking of TMCTS rings occurs through Si–Si, Si–CH2–Si, Si–O–Si, and Si–CH2–O–Si moieties. The films deposited from mixtures of TMCTS and organic precursor incorporate hydrocarbon fragments into the films. This incorporation occurs most probably through the reaction of the organic precursor and the Si–H bonds of TMCTS. Annealing the SiCOH films deposited fro...

Structure of low dielectric constant to extreme low dielectric constant SiCOH films: Fourier transform infrared spectroscopy characterization

We report the bulk preparation of nanocrystalline Si−SiO2 (nc-Si/SiO2) composites via straightforward reductive thermal annealing of a well-defined molecular precursor, hydrogen silsesquioxane. The presented method affords quantitative yields of composite powders in large quantities. Freestanding, hydride-surface-terminated silicon nanocrystals that photoluminesce throughout the visible spectrum are readily liberated from nc-Si/SiO2 composite powders upon etching in ethanol−water solutions of hydrofluoric acid. Composites and freestanding particles were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FT−IR), and thermogravimetric analysis (TGA).

Hydrogen Silsesquioxane: A Molecular Precursor for Nanocrystalline Si−SiO2 Composites and Freestanding Hydride-Surface-Terminated Silicon Nanoparticles

Provided are a novel compound for an organic electronic material and an organic electroluminescent device using the same. The compound for an organic electronic material according to the present invention has high electron transport efficiency, thereby preventing crystallization at the time manufacturing of a device, and allows a layer to be easily formed, thereby improving current characteristics of the device, and thus an OLED device having a lowered driving voltage and improved power efficiency as well as superior luminous efficiency and lifespan characteristics as compared with the existing material can be manufactured.

Novel compounds for organic electronic material and organic electroluminescent device using the same

A novel starlike polyfluorene derivative, PFO-SQ, was synthesized by the Ni(0)-catalyzed reaction of octa(2-(4-bromophenyl)ethyl)octasilsesquioxane (OBPE-SQ) and polydioctylfluoroene (PFO). The incorporation of the silsesquioxane core into polyfluorene could significantly reduce the aggregation as well as enhance the thermal stability. The DSC study showed an elimination of the glass transition and crystallization as well as a significant reduction of the melting enthalpy in PFO-SQ. The UV−vis absorption spectra in a different solvent combination or solid-state film showed an intensity reduction of the aggregation peak for PFO-SQ in comparison with that of PFO. The stability of the photoluminescence spectra of PFO-SQ could be up to 150 °C, while that of PFO showed a significant green emission at 530 nm. A single-layer LED device using PFO-SQ showed a turn on voltage of 6.0 V, a brightness of 5430 cd/m2 (at a drive voltage of 8.8 V), and a current density of 0.844 A/cm2. The maximum luminescence intensity ...

Synthesis and Optoelectronic Properties of Starlike Polyfluorenes with a Silsesquioxane Core

The structures and properties of hydrogen silsesquioxane (HSQ) films produced by curing were studied in the temperature range of 240–340 °C for various curing times. The experimental results show that the transformation of the cage structure to the network structure is the major reaction in the studied temperature range. The cage–network transformation can be explained by two-stage zero order kinetics. The rate constant of the first stage is 10–35 times more than that of the second stage. The activation energy and frequency factor of the cage–network transformation are 64.63 kJ mol−1 and 2.76 × 104 s−1 for the first stage while those of the second stage are 38.59 kJ mol−1 and 4.11 s−1, respectively. The difference is probably because the network structure of the second stage limits the structural transformation and results in a small frequency factor. The
porosity of the cured HSQ films increases rapidly with curing time in the first 10 min and then slowly for the remaining time. The FE-SEM (Field Emission-Scanning Electron Miscroscope) result suggests the formation of nano-pores in the cured film. The evolution of porosity is probably due to the outgassing of the reaction side-product (SiH4), the trapped solvent (4-methylpentan-2-one) or the cage/network transformation. The last two factors contribute significantly as shown by the refractive index results of the cured films. The increasing film thickness with increasing curing time and temperature indicates the evolution of porosity in the HSQ film.

The structures and properties of hydrogen silsesquioxane (HSQ) films produced by thermal curing

In this study, the structural transformation and properties of five commercially available poly(silsesquioxanes) by thermal curing were investigated, including poly(hydrogen silsesquioxanes) (HSQ and T12), and poly(methylsilsesquioxanes) (MSQ, T7 and T9) These materials with a different cage/network ratio and side groups (Si–H and Si–CH3) The FTIR spectra show that the poly(silsesquioxane) films have different contents of the Si–O–Si cage and network structures, which significantly affects the refractive index and dielectric constant The shifting of the Si–O–Si network band in the FTIR spectra can be correlated with their molecular structures The refractive indices and dielectric constants of the studied poly(silsesquioxane) films increase with increasing the Si–O–Si network content The retention of the Si–H or Si–CH3 side group suggests the existence of the cage structures in the poly(silsesquioxane) films The Si–O–Si cage structure results in a larger free volume than the Si–O–Si network structure in the poly(silsesquioxane) films and thus reduces the refractive index and dielectric constant It is supported by the porosity result The order of the refractive index in the studied poly(silsesquioxanes) films is T12>HSQ for the Si–H side group and T7>T9>MSQ with the Si–CH3 side group, which can be correlated with the Si–O–Si network content The poly(silsesquioxane) film with the Si–CH3 side group has a lower refractive index than the Si–H side group at the same Si–O–Si network content, which is probably due to the steric hindrance effect of the CH3 group

The structural transformation and properties of spin-on poly(silsesquioxane) films by thermal curing

http://ntur.lib.ntu.edu.tw/bitstream/246246/87104/1/09.pdf

Low dielectric constant nanoporous poly(methyl silsesquioxane) using poly(styrene-block-2-vinylpyridine) as a template

New alternating copolymers of poly(2,7-(9,9′-dihexylfluorene)-alt-3,9-(5,11-di(2-ethylhexyl)-indolo[3,2-b]carbazole)) (PF-p-In) and poly(2,7-(9,9′-dihexylfluorene)-alt-2,8-(5,11-di(2-ethylhexyl)-indolo[3,2-b]carbazole)) (PF-m-In) were synthesized by palladium-catalyzed Suzuki coupling polymerization and characterized for the applications of light-emitting diodes and field effect transistors (FET). The incorporation of indolocarbazole into polyfluorene could not only enhance hole transporting properties but also thermal properties. The para-linkage, PF-p-In, facilitates π-electron delocalization and thus has a lower optical band gap and a higher emission maximum than those of the meta linkage, PF-m-In. The electroluminescence devices based on PF-p-In and PF-m-In as the emissive layer show a similar maximum luminance but with different emissive colors of green and blue, respectively. The FET hole mobilities of PF-p-In and PF-m-In are 6.73×10−5 and 1.50×10−4 cm2/V·s, respectively, which are significantly higher than that of polyfluorene. The present study demonstrates the electronic and optoelectronic properties of polyfluorene enhanced by incorporating hole transporting indolocarbazole with different linkages.

/pdf/synthesis-of-new-fluorene-indolocarbazole-alternating-4gn3s42veu.pdf

Chang-Chung Yang

Papers

The structures and properties of hydrogen silsesquioxane (HSQ) films produced by thermal curing

The structural transformation and properties of spin-on poly(silsesquioxane) films by thermal curing

Low dielectric constant nanoporous poly(methyl silsesquioxane) using poly(styrene-block-2-vinylpyridine) as a template

Synthesis of New Fluorene-Indolocarbazole Alternating Copolymers for Light-Emitting Diodes and Field Effect Transistors

Effect of alumina on the superconducting properties of BiSrCaCu2Oy