Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Stress-free path to stress-free metallic films paves the way for next-gen circuitry: Optimized sputtering technique helps minimize stress in tungsten thin films

(top left) An illustration of the HiPIMS process (top right) The energy distribution of tungsten ions arriving at the substrate over time. At short times, there are a large proportion of ions with high energy. (bottom) Stress-free tungsten films created with the selective pulsed bias technique. (a) Plan view transmission electron microscopy (TEM) image of the film; (b) a higher resolution image; (c) reconstructions of the selected area in (b) based on inverse Fourier transforms, with two regions magnified.

CREDIT
Tokyo Metropolitan University
(top left) An illustration of the HiPIMS process (top right) The energy distribution of tungsten ions arriving at the substrate over time. At short times, there are a large proportion of ions with high energy. (bottom) Stress-free tungsten films created with the selective pulsed bias technique. (a) Plan view transmission electron microscopy (TEM) image of the film; (b) a higher resolution image; (c) reconstructions of the selected area in (b) based on inverse Fourier transforms, with two regions magnified. CREDIT Tokyo Metropolitan University

Abstract:
Researchers from Tokyo Metropolitan University have used high power impulse magnetron scattering (HiPIMS) to create thin films of tungsten with unprecedentedly low levels of film stress. By optimizing the timing of a "substrate bias pulse" with microsecond precision, they minimized impurities and defects to form crystalline films with stresses as low as 0.03 GPa, similar to those achieved through annealing. Their work promises efficient pathways for creating metallic films for the electronics industry.

Stress-free path to stress-free metallic films paves the way for next-gen circuitry: Optimized sputtering technique helps minimize stress in tungsten thin films

Tokyo, Japan | Posted on July 4th, 2021

Modern electronics relies on the intricate, nanoscale deposition of thin metallic films onto surfaces. This is easier said than done; unless done right, "film stresses" arising from the microscopic internal structure of the film can cause buckling and curving over time. Getting rid of these stresses usually requires heating or "annealing". Unfortunately, many of the best metals for the job e.g. tungsten have high melting points, meaning that the film needs to be heated to over 1000 degrees Celsius. Not only is this energy intensive, but it severely limits which substrate materials can be used. The race is on to create films out of high melting point metals without these stresses in the first place.

A team led by Associate Professor Tetsuhide Shimizu of Tokyo Metropolitan University have been working with a technique known as high power impulse magnetron scattering (HiPIMS), a sputtering technique. Sputtering involves applying a high voltage across a metallic "target" and a substrate, creating a plasma of charged gas atoms which bombards the metallic target and forms a charged metal vapor; these metal ions fly towards the substrate where they form a film. In the case of HiPIMS, the voltage is pulsed in short, powerful bursts. After each pulse, it is known that there is some separation between the arrival of metal and gas ions at the substrate; a synchronized "substrate bias" pulse can help selectively accelerate the metal ions, creating denser films. Yet despite many efforts, the issue of residual stress remained.

Now, using argon gas and a tungsten target, the team looked at how ions with different energies arrived at the substrate over time in unprecedented detail. Instead of using a bias pulse set off at the same time as the HiPIMS pulse, they used their knowledge of when different ions arrived and introduced a tiny delay, 60 microseconds, to precisely select for the arrival of high energy metal ions. They found that this minimized the amount of gas ending up in the film and efficiently delivered high levels of kinetic energy. The result was a dense crystalline film with large grains and low film stress. By making the bias stronger, the films became more and more stress-free. The efficient delivery of energy to the film meant that they had, in fact, achieved a similar effect to annealing while they deposited the film. By further swapping out argon for krypton, the team realized films with a stress as low as 0.03 GPa, comparable to what can be made with post-annealing.

An efficient pathway to stress-free films will have a significant impact on metallization processes and the manufacture of next-generation circuitry. The technology may be applied to other metals and promises big gains for the electronics industry.

###

This work was supported by the Fund for the Promotion of Joint International Research (No.17KK0136) of the Japan Society for the Promotion of Science (JSPS), the Swedish Research Council (No. VR 2018-04139), and the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No. 2009-00971).

####

For more information, please click here

Contacts:
Go Totsukawa

81-426-772-728

@TMU_PR

Copyright © Tokyo Metropolitan University

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

RELATED JOURNAL ARTICLE:

Related News Press

News and information

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Thin films

Thin-film, high-frequency antenna array offers new flexibility for wireless communications November 5th, 2021

Leibniz Prize winner Professor Dr. Oliver G. Schmidt moves to Chemnitz University of Technology: President Professor Dr. Gerd Strohmeier refers to an 'absolute top transfer' September 10th, 2021

Thin is now in to turn terahertz polarization: Rice lab’s discovery of ‘magic angle’ builds on its ultrathin, highly aligned nanotube films May 20th, 2021

FEFU scientists are paving way for future tiny electronics and gadgets August 28th, 2020

Govt.-Legislation/Regulation/Funding/Policy

UNC Charlotte-led team invents new anticoagulant platform, offering hope for advances for heart surgery, dialysis, other procedures July 15th, 2022

Strain-sensing smart skin ready to deploy: Nanotube-embedded coating detects threats from wear and tear in large structures July 15th, 2022

Rensselaer researchers learn to control electron spin at room temperature to make devices more efficient and faster: Electron spin, rather than charge, holds the key July 15th, 2022

Crystal phase engineering offers glimpse of future potential, researchers say July 15th, 2022

Possible Futures

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Chip Technology

The best semiconductor of them all? Researchers have found a material that can perform much better than silicon. The next step is finding practical and economic ways to make it July 22nd, 2022

Buckyballs on gold are less exotic than graphene July 22nd, 2022

Quantum computer works with more than zero and one: Quantum digits unlock more computational power with fewer quantum particles July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Discoveries

HKU physicists found signatures of highly entangled quantum matter July 22nd, 2022

How different cancer cells respond to drug-delivering nanoparticles: The findings of a large-scale screen could help researchers design nanoparticles that target specific types of cancer July 22nd, 2022

The best semiconductor of them all? Researchers have found a material that can perform much better than silicon. The next step is finding practical and economic ways to make it July 22nd, 2022

Buckyballs on gold are less exotic than graphene July 22nd, 2022

Materials/Metamaterials

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Strain-sensing smart skin ready to deploy: Nanotube-embedded coating detects threats from wear and tear in large structures July 15th, 2022

New protocol for assessing the safety of nanomaterials July 1st, 2022

Nanotubes: a promising solution for advanced rubber cables with 60% less conductive filler June 1st, 2022

Announcements

Quantum computer works with more than zero and one: Quantum digits unlock more computational power with fewer quantum particles July 22nd, 2022

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

UNC Charlotte-led team invents new anticoagulant platform, offering hope for advances for heart surgery, dialysis, other procedures July 15th, 2022

Photoinduced large polaron transport and dynamics in organic-inorganic hybrid lead halide perovskite with terahertz probes July 8th, 2022

Luisier wins SNSF Advanced Grant to develop simulation tools for nanoscale devices July 8th, 2022

Solving the solar energy storage problem with rechargeable batteries that can convert and store energy at once June 24th, 2022

Research partnerships

Crystal phase engineering offers glimpse of future potential, researchers say July 15th, 2022

New technology helps reveal inner workings of human genome June 24th, 2022

Boron nitride nanotube fibers get real: Rice lab creates first heat-tolerant, stable fibers from wet-spinning process June 24th, 2022

Undergrads begin summer quantum research with support from Moore Foundation, Chicago region universities, national labs: Inaugural cohort of students join quantum research labs around the Midwest, planting the seeds for a diverse and inclusive quantum workforce June 17th, 2022

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