Lasers probe chips for flaws

17 Jun 2002

Scientists have developed a new laser-probe technique that they claim identifies weak points in silicon chips.

Researchers at the Technische Universität Wien, Austria, have developed a method to track temperature changes in a chip that could warn manufacturers of potential component failure. Local temperature increases in a silicon chip, which are caused by current flow, lead to changes in the refractive index of silicon. Erich Gornik and his colleagues at the University of Vienna realized that by using lasers they could harness this phenomenon to detect any critical "hotspots".

The team focused two lasers at a silicon chip: a reference laser was directed at a known cold spot (that had no current flowing through it), while a second laser probed an uncharacterized area. By using detectors to measure any phase differences between the reflected laser beams (which signify changes in the silicon's refractive index), the researchers were able to identify temperature changes between different areas of the chip at micrometer resolutions.

Gornik and his team can also linescan a selected area on a component to produce detailed images of its temperature distribution. This method detects the so-called hotspots before they burn through a chip. The researchers believe that it will be invaluable to chip manufacturers who wish to check component prototypes before production.