Featured Research

from universities, journals, and other organizations

New Process Coats Computer Hard Drives With Diamond Armor

Date:
October 10, 1997
Source:
Lawrence Berkeley National Laboratory
Summary:
Lawrence Berkeley National Lab researchers have devised a method of magnetically filtering plasmas produced by cathodic-arc deposition, allowing the deposition of 85% diamond-like carbon films less than 10 nanometers thick. This "diamond armor" allows closer contact between computer hard disks and sliders (reader heads), promising greater data density.

BERKELEY, CA -- With help from Ernest Orlando Lawrence BerkeleyNational Laboratory researchers, the storage capacity of your computer'shard drive is about to advance dramatically.

Simone Anders of the Accelerator and Fusion Research Division atBerkeley Lab and her colleagues from IBM and UC Berkeley have found away to shield disks and sliders, or reader heads, with ultra-thin"overcoats" of diamond-like carbon that can survive repeated crashlandings at 3600 rpm. IBM has already brought to market disks that store 2.64 gigabytes ofdata per square inch; densities almost twice that have beendemonstrated, and researchers are aiming for 10 gigabytes per squareinch and more. To read a disk where magnetic domains are packed only 25nanometers apart, disk surface and slider will have to move so close toeach other that it's almost a matter of semantics whether they willactually be touching. Typical high-quality commercial overcoats now in use are made ofsputtered-on, hydrogenated carbon 12 to 15 nanometers thick. Higher datadensities require reduced magnetic spacing between heads and disks --thus disk coatings must be thinner and made of even harder material.Sputtering can't do the job.

"For decades, tool manufacturers have put titanium nitride and otherhard coatings on the cutting edges of their tools using a techniquecalled cathodic arc deposition," says Anders. Unlike sputtering -- inwhich the coating material is knocked off the cathode of the plasmasource by ions, forming a plasma mixed with un-ionized (electricallyneutral) atoms -- cathodic arcs produce a fully ionized plasma ofwhatever material, including carbon, is used for the cathode. "Since the1970s it has been known that carbon deposited this way is almost as hardas diamond," Anders notes. A fully ionized carbon plasma allows electrons and carbon nuclei toreassemble themselves as diamond, in a three-dimensional lattice inwhich each atom is bound to four others by electron pairs -- atetrahedral bond. By contrast, atoms in graphite are bound to only threeother atoms, forming a much less stable configuration. By tuning theenergy of the incoming carbon ions, the tetrahedral-bond content of thedeposited film can be optimized; thus films have been made that, whiletechnically amorphous, are 85 percent diamond.

"Still, the method hasn't been practical for coating disks," saysAnders, "because micron-sized chunks of the cathode boil off andcontaminate the films." A micron-sized macroparticle in a nanometer-scale overcoat is like a mountain in a mud puddle, a thousand timesbigger. For cathodic arc deposition to be useful in coating disks andsliders, a way must be found to completely filter out themacroparticles.

"What our team has done is to devise a filter so good that all ourgoals" -- of thin, flat, hard, macroparticle-free carbon -- "werefulfilled," Anders says. The secret is a magnetic coil that looks muchlike a Slinky toy, placed between the plasma source and the substrate tobe coated. The fully ionized plasma is easily bent through this S-shapedmagnetic field -- effectively two fields at right angles -- but themassive macroparticles of carbon can't turn easily; they fly rightthrough the sides of the coil or pile up on its walls. A coil that hasbeen used for some time is thickly coated with a dust of macroparticlesnear the plasma source, yet dust-free at the substrate end.

After perfecting the filtering method, Anders and her colleaguesperformed a series of brutal endurance tests, pitting disks withcathodic arc-deposited carbon coatings against samples with sputtered,hydrogenated carbon coats.

They found that disks coated with cathodic arc carbon had acoefficient of friction half that of those coated with hydrogenatedcarbon and caused 20 times less wear on the slider. In additionalstudies, when a silicon wafer coated with cathodic arc carbon wasexamined at nanometer scale after repeated loading, it showed virtuallyno scratches. Slider tests were equally dramatic. Weighted sliders were repeatedlyset down on spinning disks coated with hydrogenated carbon. As could beexpected, uncoated sliders failed after only 7500 cycles -- they blew upand dug trenches in the disks -- but sliders coated with cathodic arccarbon were still going strong after 100,000 cycles, with no visiblewear on the disk. The team announced these spectacular results in July, "and we'vereceived lots of requests for information," says Anders. "We are quitehopeful that cathodic arc-deposited carbon will find wide use inindustry."

Details and results of the cathodic-arc carbon deposition andfiltering system will be published in the October edition of DataStorage magazine. Berkeley Lab is a U.S. Department of Energy national laboratorylocated in Berkeley, California. It conducts unclassified scientificresearch and is managed by the University of California.


Story Source:

The above story is based on materials provided by Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Lawrence Berkeley National Laboratory. "New Process Coats Computer Hard Drives With Diamond Armor." ScienceDaily. ScienceDaily, 10 October 1997. <www.sciencedaily.com/releases/1997/10/971005124230.htm>.
Lawrence Berkeley National Laboratory. (1997, October 10). New Process Coats Computer Hard Drives With Diamond Armor. ScienceDaily. Retrieved July 25, 2014 from www.sciencedaily.com/releases/1997/10/971005124230.htm
Lawrence Berkeley National Laboratory. "New Process Coats Computer Hard Drives With Diamond Armor." ScienceDaily. www.sciencedaily.com/releases/1997/10/971005124230.htm (accessed July 25, 2014).

Share This




More Computers & Math News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Bill Gates: Health, Agriculture Key to Africa's Development

Bill Gates: Health, Agriculture Key to Africa's Development

AFP (July 24, 2014) Health and agriculture development are key if African countries are to overcome poverty and grow, US software billionaire Bill Gates said Thursday, as he received an honourary degree in Ethiopia. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Facebook Earnings Put Smile on Investors Faces

Facebook Earnings Put Smile on Investors Faces

Reuters - Business Video Online (July 23, 2014) Facebook earnings beat forecasts- with revenue climbing 61 percent. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

    Health News

      Environment News

        Technology News



          Save/Print:
          Share:

          Free Subscriptions


          Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

          Get Social & Mobile


          Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

          Have Feedback?


          Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
          Mobile: iPhone Android Web
          Follow: Facebook Twitter Google+
          Subscribe: RSS Feeds Email Newsletters
          Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins