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
New concept for structural colors
18.05.2018 | Technische Universität Hamburg-Harburg
Saarbrücken mathematicians study the cooling of heavy plate from Dillingen
17.05.2018 | Universität des Saarlandes
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...
A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.
The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...
Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.
Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...
A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.
Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...
02.05.2018 | Event News
13.04.2018 | Event News
12.04.2018 | Event News
18.05.2018 | Power and Electrical Engineering
18.05.2018 | Information Technology
18.05.2018 | Information Technology