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
Barely scratching the surface: A new way to make robust membranes
13.12.2018 | DOE/Argonne National Laboratory
Topological material switched off and on for the first time
11.12.2018 | ARC Centre of Excellence in Future Low-Energy Electronics Technologies
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.
Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Physics and Astronomy
14.12.2018 | Health and Medicine
14.12.2018 | Life Sciences