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:6/23/2016)... (PRWEB) , ... June 23, 2016 , ... ... is exhibiting at the Pennsylvania Convention Center and will showcase its product’s latest ... ClinCapture will also be presenting a scientific poster on Disrupting Clinical Trials in ...
(Date:6/23/2016)... , ... June 23, 2016 , ... ... new line of intelligent tools designed, tuned and optimized exclusively for Okuma CNC ... in Chicago. The result of a collaboration among several companies with expertise in ...
(Date:6/23/2016)... 2016 ReportsnReports.com adds 2016 ... its pharmaceuticals section with historic and forecast data ... more. Complete report on the Cell ... 15 companies and supported with 261 tables and ... . The Global Cell Culture Media ...
(Date:6/22/2016)... 22, 2016 Research and Markets has announced ... report to their offering. ... from $29.3 billion in 2013. The market is expected to grow ... 2015 to 2020, increasing from $50.6 billion in 2015 to $96.6 ... during the forecast period (2015 to 2020) are discussed. As well, ...
Breaking Biology Technology:
(Date:4/28/2016)... First quarter 2016:   , Revenues amounted ... quarter of 2015 The gross margin was 49% (27) ... the operating margin was 40% (-13) Earnings per share ... operations was SEK 249.9 M (21.2) , Outlook   ... M. The operating margin for 2016 is estimated to ...
(Date:4/19/2016)... , UAE, April 20, 2016 ... implemented as a compact web-based "all-in-one" system solution for ... biometric fingerprint reader or the door interface with integration ... modern access control systems. The minimal dimensions of the ... readers into the building installations offer considerable freedom of ...
(Date:4/14/2016)... 2016 BioCatch ™, the ... announced the appointment of Eyal Goldwerger as ... Goldwerger,s leadership appointment comes at a time of ... deployment of its platform at several of the world,s ... discerns unique cognitive and physiological factors, is a winner ...
Breaking Biology News(10 mins):