NEC Enables Continuous LSI Operation During Logic Circuit Failure

NEC Corporation and NEC Electronics Corporation have successfully developed a fundamental technology that enables an LSI device to continue operating correctly, even in the event of circuit failure in part of the LSI’s logic. This technology will resolve numerous serious problems that are expected to arise in ultra-fine LSI devices of the future, such as an increase in failures, thereby reducing the cost of sustaining high reliability.

This newly developed technology incorporates a number of key features.

  1. A circuit has been developed to predict failures in the LSI’s operation before the chip malfunctions.
  2. The logic circuits have been fragmented, and redundant circuits have been incorporated for each fragment to enable compensation for multiple defects. Together with the failure prediction circuit, this fragmentation enables compensation without any system disturbance, even in the event of multiple failures on the same LSI.

As technology advances, humans are developing an increasingly symbiotic relationship with machines, relying on them to perform critical functions where failures are unacceptable. For example, cars that drive themselves, or robotic systems that help people with physical disabilities, must handle an array of highly advanced functions with extremely high reliability. The resulting demand for lower-costs and higher-performance LSIs has led to even greater expectations for technologies that will support ultra-fine LSIs.

However, with the evolution of ultra-fine LSIs, minor flaws such as foreign particles or variations in the manufacturing process, or positional variations on the atomic level, now have a greater adverse effect on performance. The higher density of LSIs also makes it difficult to eliminate failures that result from deterioration, where defects that were not evident during the testing phase become noticeable over time(*1).

For example, one conventional method of maintaining reliability using microprocessor units (MPUs) involved the use of redundant circuits, in which whole MPUs were duplicated or even triplicated so that a backup MPU could be used in the event of a failure of the main circuit. Although this method was somewhat effective, it led to increased costs, and still did not offer protection in the event of failures in multiple MPUs.

To address the cost issue and enable reliable operation in the event of multiple failures, NEC and NEC Electronics developed a fine-grain fragmentation technique and failure prediction technology. Fragmenting the MPUs into fine-grain redundant blocks contains the failures within blocks, so that they do not affect an entire MPU; the scheme requires just two MPUs to achieve very high reliability. This new method makes it possible to incorporate extremely fine redundant circuits, even in logic circuits, to compensate for multiple failures.

The failure prediction technology discovers anomalies and compensates for failures even before they manifest, leading to improved performance. Furthermore, the technology can pinpoint the location of the defects, which will prove useful in improving the manufacturing process for similar ultra-fine LSIs in the future.

NEC and NEC Electronics will continue to undertake research and development activities aimed at providing customers with highly reliable, low-cost LSI products that offer outstanding performance and peace of mind.

The companies will present results of this technology development on February 14 at the International Solid-State Circuits Conference (ISSCC 2007), being held February 11-15 in San Francisco.

*1 There are two types of “deterioration over time”: deterioration that leads to early stage failures soon after an LSI begins operations, and deterioration over several years, which results in failures in later stages of usage. The newly developed technology can be applied to both types of deterioration, but is limited to ones that lead to increased delay time in circuits.

About NEC Corporation
NEC Corporation (Nasdaq: NIPNY) is one of the world’s leading providers of Internet, broadband network and enterprise business solutions dedicated to meeting the specialized needs of its diverse and global base of customers. NEC delivers tailored solutions in the key fields of computer, networking and electron devices, by integrating its technical strengths in IT and Networks, and by providing advanced semiconductor solutions through NEC Electronics Corporation. The NEC Group employs more than 150,000 people worldwide.

About NEC Electronics
NEC Electronics Corporation (TSE: 6723) specializes in semiconductor products encompassing advanced technology solutions for the high-end computing and broadband networking markets, system solutions for the mobile handset, PC peripherals, automotive and digital consumer markets, and platform solutions for a wide range of customer applications.