Low dielectric constant polymers for microelectronics

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.

A high performance interconnection network on a chip is essential to match the ever improving performance of the semiconductor devices they interconnect. This issue reviews the need, some fundamental background justifying the need, approaches one can take in trying to satisfy the need, and associated issues related to the concept of multilevel interconnection (MLI) technology for the ULSI/GSI era of the silicon integrated circuits, with emphasis on materials and the processes that will lead to an acceptable MLI scheme. Thus besides discussing the MLI concepts and implementation issues, properties of metals and their alloys (especially those of Cu and Al), diffusion barrier/adhesion promoter, interlayer dielectrics, deposition and etching of mateials, planarization issues, reliability issues, and new materials concepts are presented. Emphasis is obviously placed on the presently focused research on replacing aluminum with copper based interconnections. The author's viewpoint on gradual changes in replacing current materials with newer mateials as they become available is also presented. A synergism between the materials sets for on-chip and off-chip interconnections has been pointed out.

Multilevel interconnections for ULSI and GSI era

https://www.seas.ucla.edu/%7Epilon/Publications/Thin%20Solid%20Films2006.pdf

Effective optical properties of non-absorbing nanoporous thin films

Luft, Luft, Luft … und wenig festes Gerust, das ist die Grundlage fur eine interessante Materialklasse – die Aerogele (rechts schematisch gezeigt). Doch kann man deshalb von einer „leichten” Chemie reden? Das Design eines so filigranes Netzwerks bedarf einer auserst genauen Kontrolle und Einstellung der chemischen Parameter. Dank der Reichhaltigkeit der Variationsmoglichkeiten wird man dann aber mit einer Vielfalt von unterschiedlichen Eigenschaftsprofilen belohnt.

Aerogele – luftige Materialien: Chemie, Struktur und Eigenschaften

Low density silica xerogels have many properties which suggest their use as a low dielectric constant material. Recent process improvements to control capillary pressure and strength by employing aging and pore chemistry modification, such that shrinkage is minimal during ambient pressure drying, have eliminated the need for supercritical drying. Although xerogels offer advantages for intermetal dielectric (IMD) applications because of their low dielectric constant (<2), high temperature limit, and compatibility with existing microelectronics precursors and processes, they suffer from unanswered questions. These include: 1) are all pores smaller than microelectronics features, 2) what are their mechanical properties (for processing and particle generation), and 3) what is their thermal stability. We have produced bulk xerogels under similar conditions to those used for films and studied the effect of density on the pore size distribution and bulk modulus.

Preparation Of Low-Density Xerogels At Ambient Pressure For Low K Dielectrics

Low dielectric-constant insulators for electronics applications

Using molecular beam epitaxy (MBE), we have grown high quality, low stress, single crystal Al on Si( 111) and CaF2(111). Xs-ray diffraction was used to characterize the crystalline quality, stress, and epitaxial relations of the films. AI(lll) was grown at a substrate temperature as low as 25°C on ass-deposited CaF2(111) and Si(111) cleaned by either wet etching or high temperature annealing. Aluminum Film stresses, derived from deformation of the Al atomic planes, are compressive when the films are grown at low temperatures. The stress becomes tensile and increases as the growth temperature increases. Consequently, films of low stress can be achieved by choosing the appropriate growth temperature. Epitaxial relations are dependent on the growth temperature and Si substrate preparation methods. Aluminum films with crystalline orientations identical to the substrates (A type), rotated 180° about the surface normal of the substrates (B type), and mixed A and B types have been observed.

Low Temperature Epitaxial Growth of Al on Si( 111) and CaF2(111) Using Molecular Beam Epitaxy

By thermally evaporating CaF2 and NdF3, we have grown Nd-doped CaF2 films on Si(III), Al/Si(III) and quarter-wavelength Ta2O5/SiO2 multilayer Bragg reflectors. The optical and structural properties of the CaF2:Nd films are characterized by photoluminescence spectroscopy (PL) and x-ray diffraction. The effects of different Nd concentration, growth temperatures and post-annealing were studied. Regardless of the substrates, the as-grown films show emission lines at wavelengths similar to bulk CaF2:Nd. Annealing the films at 700°C in forming gas results in a new emission pattern. Little difference between the PL spectra of polycrystalline and single crystal CaF2:Nd films is observed, indicating that the luminescence efficiency is insensitive to the crystalline quality of the films.

Optical and structural properties of CaF2: Nd films on Si-based substrates

When preparing singles-crystal films of CaF2 on (111) oriented silicon by molecular beam epitaxy (MBE), we found that these dielectric films grew into either A or B type depending on the substrate temperature during growth. As-type films follow the same orientation as that of the substrate silicon, while Bs-type films rotate 180° about the surface normal with respect to the substrates. p]Xs-ray diffraction (XRD) confirms the single crystallinity and identifies the epitaxial relationships between the film and the substrate. Epitaxial CaF2 films were obtained at growth temperatures ranging from 200°C to 800°C. Employing the asymmetric xs-ray diffraction of atomic planes inclined to the sample surface, we found that As-type CaF2 grows at lower substrate temperatures, while Bs-type films dominate at higher temperatures.

A Study of Epitaxial Relations of CaF2 Films Grown on (111) Silicon by Molecular Beam Epitaxy

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

C.-C. Cho

Author Tools

Chat about Author