The new technique could help improve the reliability and manufacturability of ICs and, better yet, it’s one that state-of-the-art microelectronics manufacturers can use with equipment they already own.
At issue is the mechanical strength of so-called “low-k” dielectric layers—electrically insulating films only a couple of micrometers thick that are interleaved between layers of conductors and components in microprocessor chips and other high-performance semiconductor devices. As IC features like transistors have gotten ever smaller and crammed more closely together, designers are preventing electrical interference or “cross-talk” by making the insulating films more and more porous with nanoscale voids—but this has made them more fragile. Brittle fracture failure of low-k insulating films remains a problem for the industry, affecting both manufacturing yields and device reliability. To date, there has been no accurate method to measure the fracture resistance of such films, which makes it difficult to design improved dielectrics.
NIST researchers believe they have found an answer to the measurement problem in a new adaptation of a materials test technique called nanoindentation. Nanoindentation works by pressing a sharp, hard object—a diamond tip—and observing how much pressure it takes to deform the material. For roughly 20 years, researchers have known how to measure elasticity and plasticity—the forces needed to bend a material either temporarily or permanently—of materials at very small scales with nanoindenters. But toughness, the force needed to actually break the material, has been, well, tougher. Thin films were particularly problematic because they necessarily must be layered on top of another stronger material, such as a silicon wafer.
The new NIST technique requires a slight modification of the nanoindentation equipment—the probe has to have a sharper, more acute point than normally used—and a hefty dose of theory. Pressing carefully on the dielectric film generates cracks as small as 300 nanometers, which are measured by electron microscopy. Just how the cracks form depends on a complex interaction involving indentation force, film thickness, film stress and the elastic properties of the film and the silicon substrate. These variables are plugged into a new fracture mechanics model that predicts not only the fracture toughness but also another key value, the critical film thickness for spontaneous fracture.
Using this methodology, device manufacturers will be able to eliminate some candidate interconnect dielectric films from consideration without further expensive device testing. The measurement technique and model were published in a two-part series in the Journal of Materials Research.*
* D.J. Morris and R.F. Cook. Indentation fracture of low-dielectric constant films: Part I. Experiments and observations. J. Mater. Res., Vol. 23, No. 9, p. 2429.
* D.J. Morris and R.F. Cook. Indentation fracture of low-dielectric constant films: Part II. Indentation fracture mechanics model. J. Mater. Res., Vol. 23, No. 9, p. 2443.
Michael Baum | Newswise Science News
Further reports about: > Cracking a Tough Nut > Semiconductor > elastic properties > film thickness > high-performance semiconductor devices > indentation force > microprocessor chips > semiconductor device > semiconductor industry > spontaneous fracture > state-of-the-art microelectronics manufacturers
Scientists announce the quest for high-index materials
24.07.2017 | Moscow Institute of Physics and Technology
ADIR Project: Lasers Recover Valuable Materials
24.07.2017 | Fraunhofer-Institut für Lasertechnik ILT
3-D shape acquisition using water displacement as the shape sensor for the reconstruction of complex objects
A global team of computer scientists and engineers have developed an innovative technique that more completely reconstructs challenging 3D objects. An ancient...
Physicists have developed a new technique that uses electrical voltages to control the electron spin on a chip. The newly-developed method provides protection from spin decay, meaning that the contained information can be maintained and transmitted over comparatively large distances, as has been demonstrated by a team from the University of Basel’s Department of Physics and the Swiss Nanoscience Institute. The results have been published in Physical Review X.
For several years, researchers have been trying to use the spin of an electron to store and transmit information. The spin of each electron is always coupled...
What is the mass of a proton? Scientists from Germany and Japan successfully did an important step towards the most exact knowledge of this fundamental constant. By means of precision measurements on a single proton, they could improve the precision by a factor of three and also correct the existing value.
To determine the mass of a single proton still more accurate – a group of physicists led by Klaus Blaum and Sven Sturm of the Max Planck Institute for Nuclear...
The research team of Prof. Dr. Oliver Einsle at the University of Freiburg's Institute of Biochemistry has long been exploring the functioning of nitrogenase....
A one trillion tonne iceberg - one of the biggest ever recorded -- has calved away from the Larsen C Ice Shelf in Antarctica, after a rift in the ice,...
21.07.2017 | Event News
19.07.2017 | Event News
12.07.2017 | Event News
24.07.2017 | Power and Electrical Engineering
24.07.2017 | Materials Sciences
24.07.2017 | Materials Sciences