Navigation Links
NIST 'stress tests' probe nanoscale strains in materials

Researchers at the National Institute of Standards and Technology (NIST) have demonstrated their ability to measure relatively low levels of stress or strain in regions of a semiconductor device as small as 10 nanometers across. Their recent results* not only will impact the design of future generations of integrated circuits but also lay to rest a long-standing disagreement in results between two different methods for measuring stress in semiconductors.

Mechanical stress and strain in semiconductors and other devices is caused by atoms in the crystal lattice being compressed or stretched out of their preferred positions, a complexand not always harmfulphenomenon. Stress in the underlying structure of light-emitting diodes and lasers can shift output colors and lower the devices lifetime. Stress in microelectromechanical systems can lead to fracture and buckling that also truncates their lifespan. On the other hand, stress is deliberately built into state-of-the-art microcircuits because properly applied it can increase the speed of transistors without making any other changes to the design. Stress engineering has allowed the semiconductor industry to increase the performance of devices well beyond what was expected with the current materials set, said NIST research physicist Robert Cook, thus avoiding the significant engineering problems and expense associated with changing materials.

Both the good and the bad stresses need to be measured, however, if theyre to be controlled by device designers. As the component size of microcircuits has become smaller and smaller, this has become more difficultparticularly since two different and widely used methods of stress measurement have been returning disparate results. One, electron back scattered diffraction (EBSD), deduces underlying stress by observing the patterns of electrons scattered back from the crystal planes. The other, confocal Raman microscopy (CRM), measures minute shifts in the frequency of photons that interact with the atomic bonds in the crystalshifts that change depending on the amount of stress on the bond. The NIST team used customized, highly sensitive versions of both instruments in a series of comparison measurements to resolve the discrepancies.

The key issue, they found, was depth of penetration of the two techniques. Electron beams sample only the top 20 or 30 nanometers of the material, Cook explained, while the laser-generated photons used in CRM might penetrate as deep as a micrometer or more. The NIST researchers found that by varying the wavelength of the Raman photons and positioning the focus of the microscope they could select the depth of the features measured by the Raman techniqueand when the CRM was tuned for the topmost layers of the crystal, the results were in close agreement with EBSD measurements.

The NIST instruments also demonstrate the potential for using the two techniques in combination to make reliable, nanoscale measurements of stress in silicon, which enables device developers to optimize materials and processes. EBSD, although confined to near-surface stress, can make measurements with resolutions as small as 10 nanometers. CRM resolution is about 10 times coarser, but it can return depth profiles of stress.


Contact: Michael Baum
National Institute of Standards and Technology (NIST)

Related biology technology :

1. BSP Signs Agreement With CMP Trading for Distribution of HyperQ(TM) Stress System, for Early Detection of Ischemic Heart Disease, in South Korea
2. StollerUSA Launches to Offer Solutions for Crops Under Stress
3. Astellas Launches Lexiscan(TM) (Regadenoson) Injection for Use as a Pharmacologic Stress Agent in Radionuclide Myocardial Perfusion Imaging (MPI)
4. World Debut for BSPs HyperQ Stress System: 57th Annual American College of Cardiology Meeting 2008
5. Nanomaterials show unexpected strength under stress
6. BASF Podcast - Better Harvest in Spite of Climate Stress
7. PCI Guideline Update Stresses Long-Term Anticoagulant Therapy After Treatment With Drug-Eluting Stents
8. Job-related stress: NIST demonstrates fatigue effects in silicon
9. New Web Site Tools Help Alleviate Stress Associated with Caring for Children with Diabetes During the Holidays
10. Gene Signal Enters Phase III Clinical Tests for the Prevention of Corneal Graft Rejection
11. Data Presented at Cancer Molecular Markers Meeting Suggests Clinical Benefit for Integrating New Molecular Tests
Post Your Comments:
Related Image:
NIST 'stress tests' probe nanoscale strains in materials
(Date:11/25/2015)... and HOLLISTON, Mass. , Nov. ... (Nasdaq: HART ), a biotechnology company developing bioengineered ... Jim McGorry will present at the LD ... 2015 at 2:30 p.m. PT. The presentation will be ... 30 days. Management will also be available at the ...
(Date:11/25/2015)... Nov. 25, 2015 /PRNewswire/ - Aeterna Zentaris Inc. (NASDAQ: ... business and prospects remain fundamentally strong and highlights ... doxorubicin) recently received DSMB recommendation to continue the ... review of the final interim efficacy and safety ... Endpoint in men with heavily pretreated castration- and ...
(Date:11/25/2015)... -- Orexigen® Therapeutics, Inc. (Nasdaq: OREX ) today ... discussion at the Piper Jaffray 27th Annual Healthcare Conference ... is scheduled for Wednesday, December 2, at 8:00 a.m. ... will be available for 14 days after the event.  ... Corporate Communications and Business Development , BrewLife(858) 875-8629 ...
(Date:11/25/2015)... , ... November 25, 2015 , ... ... uBiome, were featured on AngelList early in their initial angel funding process. Now, ... syndicate for individuals looking to make early stage investments in the microbiome space. ...
Breaking Biology Technology:
(Date:11/18/2015)...  As new scientific discoveries deepen our understanding of ... providers face challenges in better using that knowledge to ... as more children continue to survive pediatric cancer, that ... age. John M. Maris, M.D ., a ... (CHOP) . --> John M. Maris, ...
(Date:11/17/2015)... Mass. , Nov. 17, 2015 Pressure ... leader in the development and sale of broadly enabling, ... worldwide life sciences industry, today announced it has received ... its $5 million Private Placement (the "Offering"), increasing the ... $4,025,000.  One or more additional closings are expected in ...
(Date:11/11/2015)... Minn. , Nov. 11, 2015   MedNet Solutions ... entire spectrum of clinical research, is pleased to announce that ... in Clinical Trials (PCT) event, to be held November ... be able to view live demonstrations of iMedNet ... and learn how iMedNet has been able to ...
Breaking Biology News(10 mins):