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

Engineering piezoelectricity and strain sensitivity in CdS to promote piezocatalytic hydrogen evolution May 13th, 2022

New nanomechanical oscillators with record-low loss May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Study finds nanomedicine targeting lymph nodes key to triple negative breast cancer treatment: In mice, nanomedicine can remodel the immune microenvironment in lymph node and tumor tissue for long-term remission and lung tumor elimination in this form of metastasized breast cance May 13th, 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

Lightening up the nanoscale long-wavelength optoelectronics May 13th, 2022

On-Chip Photodetection: Two-dimensional material heterojunctions hetero-integration May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

The future of desalination? A fast, efficient, selective membrane for purifying saltwater May 13th, 2022

Possible Futures

Engineering piezoelectricity and strain sensitivity in CdS to promote piezocatalytic hydrogen evolution May 13th, 2022

New nanomechanical oscillators with record-low loss May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Study finds nanomedicine targeting lymph nodes key to triple negative breast cancer treatment: In mice, nanomedicine can remodel the immune microenvironment in lymph node and tumor tissue for long-term remission and lung tumor elimination in this form of metastasized breast cance May 13th, 2022

Chip Technology

Going gentle on mechanical quantum systems: New experimental work establishes how quantum properties of mechanical quantum systems can be measured without destroying the quantum state May 13th, 2022

On-Chip Photodetection: Two-dimensional material heterojunctions hetero-integration May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Rice ‘metalens’ could disrupt vacuum UV market: Solid-state nanophotonic technology could potentially replace cabinets of equipment May 6th, 2022

Discoveries

Going gentle on mechanical quantum systems: New experimental work establishes how quantum properties of mechanical quantum systems can be measured without destroying the quantum state May 13th, 2022

New nanomechanical oscillators with record-low loss May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Study finds nanomedicine targeting lymph nodes key to triple negative breast cancer treatment: In mice, nanomedicine can remodel the immune microenvironment in lymph node and tumor tissue for long-term remission and lung tumor elimination in this form of metastasized breast cance May 13th, 2022

Materials/Metamaterials

When a band falls flat: Searching for flatness in materials: International collaboration, led by DIPC and Princeton, creates a catalogue of materials that could impact quantum technologies April 1st, 2022

Studying atomic structure of aluminum alloys for manufacturing modern aircraft March 25th, 2022

Unexplored dimensions of porous metamaterials: Researchers unlock hidden potential in a long-studied group of materials March 18th, 2022

Copper doping enables safer, cost-effective hydrogen peroxide production February 11th, 2022

Announcements

Engineering piezoelectricity and strain sensitivity in CdS to promote piezocatalytic hydrogen evolution May 13th, 2022

New nanomechanical oscillators with record-low loss May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Study finds nanomedicine targeting lymph nodes key to triple negative breast cancer treatment: In mice, nanomedicine can remodel the immune microenvironment in lymph node and tumor tissue for long-term remission and lung tumor elimination in this form of metastasized breast cance May 13th, 2022

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

Lightening up the nanoscale long-wavelength optoelectronics May 13th, 2022

On-Chip Photodetection: Two-dimensional material heterojunctions hetero-integration May 13th, 2022

Small microring array enables large complex-valued matrix multiplication May 13th, 2022

Study finds nanomedicine targeting lymph nodes key to triple negative breast cancer treatment: In mice, nanomedicine can remodel the immune microenvironment in lymph node and tumor tissue for long-term remission and lung tumor elimination in this form of metastasized breast cance May 13th, 2022

Research partnerships

University of Strathclyde and National University of Singapore to co-ordinate satellite quantum communications May 13th, 2022

Rice ‘metalens’ could disrupt vacuum UV market: Solid-state nanophotonic technology could potentially replace cabinets of equipment May 6th, 2022

New quantum network shares information at a scale practical for future real-world applications: Researchers enable real-time adjustments to communication among three remote nodes in a quantum network April 22nd, 2022

Nanoclusters self-organize into centimeter-scale hierarchical assemblies April 22nd, 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