Navigation Links
Job-related stress: NIST demonstrates fatigue effects in silicon
Date:11/27/2007

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated a mechanical fatigue process that eventually leads to cracks and breakdown in bulk silicon crystalsa phenomenon thats particularly interesting because it long has been thought not to exist. Their recently published* results have important implications for the design of new silicon-based micro-electromechanical system (MEMS) devices that have been proposed for a wide variety of uses.

Siliconthe backbone of the semiconductor industryis one the worlds most heavily studied materials, and it has long been believed to be immune to fatigue from cyclic stresses because of the nature of its crystal structure and chemical bonds. And indeed, conventional tests have validated this. Recent research into silicon MEMS devices, however, has revealed that these microscopic systems that incorporate tiny gears, vibrating reeds and other mechanical features do seem to develop stress-induced cracks that can lead to failure. Why this happens at the microscopic scale is a matter of debate. One school of thought holds that the effect is purely mechanical, due to friction, and the other argues that it essentially is caused by corrosiona chemical effect. Because the effect has only been noticed at submicrometer scales, it has been difficult to determine which theory is correct.

A materials resistance to crackingreferred to as toughness by materials scientistsis measured customarily by taking a sample of the material, slightly notching one edge, and pulling on the ends repetitively to see if the tensile stress causes the notch to grow into a crack. Bulk silicon always has passed this test. But, argued the NIST team, in real-world MEMS devices the stresses are likely to be much more complicated.

To test this, they used an alternate method: pressing the top of test crystals with tiny tungsten-carbide spheres about 3 mm in diameter at pressures below the silicons breaking point. Simply pressing down hard on the crystal for days at a time caused no detectable cracksarguing against the corrosion theory. On the other hand, using half the pressure but cycling the test hundreds of thousands of times revealed a gradually increasing pattern of surface damage at the indentation siteclear indication of mechanical fatigue. The NIST team, which included a researcher from the University of Extremadura in Spain, theorizes that the critical element in their experiments is the addition of shear stress (causing the crystal planes to slide against each other), a component missing in conventional tensile strength tests but not uncommon in real-world applications.

The NIST experiments demonstrated fatigue effects in silicon at the comparatively large scale of hundred of micrometers. The next step is to determine if the same mechanisms operate at the submicrometer level.


'/>"/>

Contact: Michael Baum
michael.baum@nist.gov
301-975-2763
National Institute of Standards and Technology (NIST)  
Source:Eurekalert

Related biology technology :

1. Elekta Demonstrates Commitment to Stereotactic Innovation at EANS
2. ChemoCentryx Demonstrates Recently Discovered Chemokine Receptor CXCR7 is Essential in Tumor Growth
3. Recent Study Confirms Alimentary Healths Bifantis(R) Demonstrates Efficacy in the Treatment of Irritable Bowel Syndrome
4. Organons Asenapine Further Demonstrates Efficacy in Reducing Mania Symptoms for the Treatment of Bipolar I Disorder
5. ARRIVE Registry Analysis Demonstrates Continued Safety and Efficacy of TAXUS(R) Stent in Complex Real-World Patients
6. Magnifi Group Demonstrates Industrys First Interactive Educational Program (IEP) for Spine Fellows
7. Brostallicin Trial Data Demonstrates Encouraging Anti-tumor Activity in Patients With Chemotherapy-Resistant Cancers
8. Circulation Publishes MERLIN TIMI-36 Data Showing Safety and Anti-Arrhythmic Effects of Ranexa(R)
9. Panel to Discuss the Far-Ranging Effects and Consequences of Heart Disease, Which is the Leading Killer in Both Men and Women in the United States
10. Nanotube forests grown on silicon chips for future computers, electronics
11. Worlds most complex silicon phased-array chip developed at UC-San Diego
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Job-related stress: NIST demonstrates fatigue effects in silicon
(Date:2/21/2017)... ... February 21, 2017 , ... ... Liquid Biopsy System , a fully automated benchtop system for collecting intact circulating ... is being launched at the Molecular Medicine Tri Conference (Tri-Con) Annual Meeting 2017 ...
(Date:2/21/2017)... ... February 21, 2017 , ... Cancer diagnostics workflow solution ... its executive team to lead the development and commercialization of its Cancer Information ... the diagnosis and treatment of cancer. The CIDT addresses the need for curated ...
(Date:2/21/2017)... IL (PRWEB) , ... February ... ... of the Life -Sciences division, Treximo will pair its $200M operational capacity ... results-based consulting and project management in areas affecting quality and operational management. ...
(Date:2/21/2017)... (PRWEB) , ... February 21, 2017 , ... ... creating transformative design and manufacturing solutions for original equipment manufacturers (OEMs) , today ... 2017 marks Creation Technologies’ third consecutive year winning in its category of electronics ...
Breaking Biology Technology:
(Date:2/6/2017)... , Feb. 6, 2017 According ... security are driving border authorities to continue to ... reports there are 2143 Automated Border Control (ABC) ... currently deployed at more than 163 ports of ... 2013 to 2016 achieving a combined CAGR of ...
(Date:2/2/2017)... Feb. 2, 2017  EyeLock LLC, a market leader ... white paper " What You Should Know About Biometrics ... ensuring user authenticity is a growing concern. In traditional ... users. However, traditional authentication schemes such as username/password suffer ... Biometric authentication offers an elegant solution to the problem ...
(Date:1/30/2017)... 30, 2017   Invitae Corporation (NYSE: ... information companies, today announced that it will report its ... 2017 guidance on Monday, February 13, 2017, and Invitae,s ... at 4:45 p.m. Eastern / 1:45 p.m. Pacific. ... briefly review financial results, guidance, and recent developments and ...
Breaking Biology News(10 mins):