As microelectronics transition to nanoelectronics, and semiconductor devices reach progressively higher levels of complexity, the probability of defects in manufacturing has increased significantly. Leading edge wafers are valued at between $100,000 to $150,000 each, so defective processes could cost manufacturers millions of dollars before they can even become aware them. Since interconnect widths now span only a few hundred atoms, a major challenge to the semiconductor industry is how to better view these devices to ensure quality control and maximize profitability.
Recent research conducted by Dr. Eric Lifshin, Professor at the UAlbany College of Nanoscale Science and Engineering (CNSE), and CNSE student James Evertsen has led to important advances in an emerging technique to visualize defects through 3-D imaging. The new development, developed in conjunction with research partners, Ed Principe from Carl Zeiss, SMT and John Friel from Princeton Gammatech, involves the use of a focused ion beam instrument combined with a focused electron beam instrument, or crossbeam focused ion beam (FIB), to produce, image, store and process serial sections through electronic devices.
The Electronic Device Failure Society, the leading industrial organization focusing on testing micro and nanoelectronics devices, views this research as so promising that they selected this work to receive the Distinguished Paper Award at their most recent annual meeting, the International Symposium for Test and Failure Analysis (ISTFA). The ISTFA Distinguished Paper Award is given to one of over a hundred of papers presented, and recognizes excellence in research that can be directly applied to industrial development and manufacturing.
"A serial section can be likened to a meat slicer removing slices of meat and constantly exposing fresh surface to be examined. However in this case, the sections are 15 to 50 nanometers thick or more than 10,000 times thinner than your slice of bologna," said Profesor Lifshin, who joined CNSE after serving 25 years at General Electric Global Research as manager of the Characterization and Environmental Technology Laboratory. "Once information is obtained from all of the slices, it can be recombined to give a three dimensional reconstruction of the structure, much the same as what is done with CAT or MRI scanners only with much higher resolution."
With this technique, it is possible to view internal structures from any angle in order to observe, for example, how parts are connected or the presence of defects that could be missed in viewing a single "slice." Although the concept of 3-D imaging in combined focused ion beam/ scanning electron microscope instruments has been around now for a few years, the current work shows how the method can be used to obtain the higher resolution images than previously obtained as well as how to collect the data much faster than previously done. Furthermore, the presentation described how to optimize data collection conditions and how to obtain chemical as well as structural information at high resolution. As the microelectronics industry moves to ever smaller structures, 3-D imaging at high resolution is viewed to be an important part not only of failure analysis, but also the device development process.
Lifshin and Evertsen will officially receive their award at the next ISTFA conference, scheduled for fall 2005. They have also been asked to give the award winning paper at an upcoming international meeting on electronic failure analysis meeting in Singapore.
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