Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Tungsten offers nano-interconnects a path of least resistance: Crystalline tungsten shows insight and promise in addressing the challenges of electrical interconnects that have high resistivity at the nanoscale

The measured resistivity of epitaxial tungsten layers with (001) and (011) crystal orientation vs thickness d. The tungsten Fermi surface is color coded according to the wave vector dependent Fermi velocity vf. At small thickness, where surface scattering dominates, W(011) is nearly twice as conductive as W(001). Transport simulations indicate that this is due to the anisotropy in the Fermi surface. These results indicate how narrow wires in future computer chips can be made two times more conductive, effectively reducing the required electric power by 50 percent.
CREDIT
Daniel Gall, Rensselaer Polytechnic Institute
The measured resistivity of epitaxial tungsten layers with (001) and (011) crystal orientation vs thickness d. The tungsten Fermi surface is color coded according to the wave vector dependent Fermi velocity vf. At small thickness, where surface scattering dominates, W(011) is nearly twice as conductive as W(001). Transport simulations indicate that this is due to the anisotropy in the Fermi surface. These results indicate how narrow wires in future computer chips can be made two times more conductive, effectively reducing the required electric power by 50 percent. CREDIT Daniel Gall, Rensselaer Polytechnic Institute

Abstract:
As microchips become ever smaller and therefore faster, the shrinking size of their copper interconnects leads to increased electrical resistivity at the nanoscale. Finding a solution to this impending technical bottleneck is a major problem for the semiconductor industry.

Tungsten offers nano-interconnects a path of least resistance: Crystalline tungsten shows insight and promise in addressing the challenges of electrical interconnects that have high resistivity at the nanoscale

Washington, DC | Posted on October 4th, 2017

One promising possibility involves reducing the resistivity size effect by altering the crystalline orientation of interconnect materials. A pair of researchers from Rensselaer Polytechnic Institute conducted electron transport measurements in epitaxial single-crystal layers of tungsten (W) as one such potential interconnect solution. They performed first-principles simulations, finding a definite orientation-dependent effect. The anisotropic resistivity effect they found was most marked between layers with two particular orientations of the lattice structure, namely W(001) and W(110). The work is published this week in the Journal of Applied Physics, from AIP Publishing.

Author Pengyuan Zheng noted that both the 2013 and 2015 International Technology Roadmap for Semiconductors (ITRS) called for new materials to replace copper as interconnect material to limit resistance increase at reduced scale and minimize both power consumption and signal delay.

In their study, Zheng and co-author Daniel Gall chose tungsten because of its asymmetric Fermi surface -- its electron energy structure. This made it a good candidate to demonstrate the anisotropic resistivity effect at the small scales of interest. "The bulk material is completely isotropic, so the resistivity is the same in all directions," Gall said. "But if we have thin films, then the resistivity varies considerably."

To test the most promising orientations, the researchers grew epitaxial W(001) and W(110) films on substrates and conducted resistivity measurements of both while immersed in liquid nitrogen at 77 Kelvin (about -196 degrees Celsius) and at room temperature, or 295 Kelvin. "We had roughly a factor of 2 difference in the resistivity between the 001 oriented tungsten and 110 oriented tungsten," Gall said, but they found considerably smaller resistivity in the W(011) layers.

Although the measured anisotropic resistance effect was in good agreement with what they expected from calculations, the effective mean free path -- the average distance electrons can move before scattering against a boundary -- in the thin film experiments was much larger than the theoretical value for bulk tungsten.

"An electron travels through a wire on a diagonal, it hits a surface, gets scattered, and then continues traveling until it hits something else, maybe the other side of the wire or a lattice vibration," Gall said. "But this model looks wrong for small wires."

The experimenters believe this may be explained by quantum mechanical processes of the electrons that arise at these limited scales. Electrons may be simultaneously touching both sides of the wire or experiencing increased electron-phonon (lattice vibrations) coupling as the layer thickness decreases, phenomena that could affect the search for another metal to replace copper interconnects.

"The envisioned conductivity advantages of rhodium, iridium, and nickel may be smaller than predicted," said Zheng. Findings like these will prove increasingly important as quantum mechanical scales become more commonplace for the demands of interconnects.

The research team is continuing to explore the anisotropic size effect in other metals with nonspherical Fermi surfaces, such as molybdenum. They found that the orientation of the surface relative to the layer orientation and transport direction is vital, as it determines the actual increase in resistivity at these reduced dimensions.

"The results presented in this paper clearly demonstrate that the correct choice of crystalline orientation has the potential to reduce nanowire resistance," said Zheng. The importance of the work extends beyond current nanoelectronics to new and developing technologies, including transparent flexible conductors, thermoelectrics and memristors that can potentially store information. "It's the problem that defines what you can do in the next technology," Gall said.

####

About American Institute of Physics
Journal of Applied Physics features full length reports on significant new findings in applied physics. The journal covers new experimental and theoretical research on applications of physics phenomena related to all branches of science, engineering, and modern technology. See http://jap.aip.org .

For more information, please click here

Contacts:
Julia Majors

301-209-3090

Copyright © American Institute of Physics

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

The article, "The anisotropic size effect of the electrical resistivity of metal thin films: Tungsten," is authored by Pengyuan Zheng and Daniel Gall. The article appeared in Applied Physics Letters Oct. 3, 2017 (DOI: 10.1063/1.5004118) and can be accessed at:

Related News Press

News and information

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Iran World’s Second Largest Producer of Nano-Catalysts October 17th, 2018

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

Fat-Repellent Nanolayers Can Make Oven Cleaning Easier October 17th, 2018

Flexible Electronics

Researchers quickly harvest 2-D materials, bringing them closer to commercialization: Efficient method for making single-atom-thick, wafer-scale materials opens up opportunities in flexible electronics October 12th, 2018

CTI Materials drives nano commercialization with it's patented surfactant free nanoparticle dispersions August 15th, 2018

Physics

Searching for errors in the quantum world September 21st, 2018

How a tetrahedral substance can be more symmetrical than a spherical atom: A new type of symmetry September 14th, 2018

Ultracold atoms used to verify 1963 prediction about 1D electrons: Rice University, University of Geneva study focuses on theory that's increasingly relevant to chipmakers September 5th, 2018

Energy-efficient spin current can be controlled by magnetic field and temperature: SCMR effect simplifies the design of fundamental spintronic components August 20th, 2018

Scientists create antilaser for ultracold atoms condensate August 16th, 2018

Hardware

All wired up: New molecular wires for single-molecule electronic devices August 31st, 2018

Possible Futures

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Iran Unveils Its First Homegrown 3D Nano Printer October 17th, 2018

Rice U. announces $82 million in strategic research initiatives: Faculty, programs will expand in neuroengineering, synthetic biology, physical biology October 16th, 2018

Iranian Firm Offering Nano-Products on Chinese Market October 16th, 2018

Chip Technology

Nanometrics to Announce Third Quarter Financial Results on October 30, 2018 October 10th, 2018

Graphene controls surface magnetism at room temperature October 8th, 2018

UCI scientists push microscopy to sub-molecular resolution: Carbon monoxide used to measure electric forces in single chemical compound October 2nd, 2018

Machine learning helps improving photonic applications September 28th, 2018

Nanoelectronics

Machine learning helps improving photonic applications September 28th, 2018

How a tetrahedral substance can be more symmetrical than a spherical atom: A new type of symmetry September 14th, 2018

Laser sintering optimized for printed electronics: New study sheds (laser) light on the best means of laying down thin-film circuitry September 13th, 2018

September 5th, 2018

Discoveries

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Researchers quickly harvest 2-D materials, bringing them closer to commercialization: Efficient method for making single-atom-thick, wafer-scale materials opens up opportunities in flexible electronics October 12th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

High-performance self-assembled catalyst for SOFC October 12th, 2018

Announcements

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Arrowhead Pharmaceuticals Hosts R&D Day on Pipeline of RNAi Therapeutics October 17th, 2018

Iran Produces Cooling Fabrics Using Nanotechnology October 17th, 2018

Iran World’s Second Largest Producer of Nano-Catalysts October 17th, 2018

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Study provides insight into how nanoparticles interact with biological systems: Findings can help scientists engineer nanoparticles that are ‘benign by design’ October 18th, 2018

Big award enables study of small surfaces: Rice U.'s Matt Jones wins Packard Fellowship to view nanoscale chemical reactions October 15th, 2018

Graphene shows unique potential to exceed bandwidth demands of future telecommunications October 12th, 2018

High-performance self-assembled catalyst for SOFC October 12th, 2018

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project