Soft error testing technology that supports advanced electronic social infrastructureNTT Network Technology Laboratories


    In recent years, semiconductor devices have come to use more highly integrated circuits, enabling communication equipment to have higher functionality and higher performance, but this has also led to higher risk of soft errors (temporary memory errors) caused by high energy neutrons in cosmic rays. For this reason, NTT has assumed there will be more soft errors in the future, and has established design methods for communication equipment so that affect communication services and maintenance will not be adversely affected even when a soft error occurs. NTT has also developed soft error regeneration testing technology that can confirm the operation and effects of countermeasure effect when soft errors do occur.

    Background and Conventional Challenges

    In recent years, communications devices have experienced more soft errors caused by high energy neutrons in cosmic rays. Unlike hardware errors which cause permanent failure of a device, soft errors are temporary failures that can be recovered from by restarting or overwriting the device. When a soft error occurs in a communication device, it can trigger various failure modes and have an impact communication service. Communication equipment is designed accounting for such failures so as to prevent an impact on communication services, but because it is difficult to recreate soft errors, it was impossible to verify these designs. As a result of this, there was unexpected operation in communication devices.

    Advantages of this technology

    • Instantly regenerates soft errors by irradiating devices with 100 million times more neutrons than occur in natural cosmic rays
    • Can be used to evaluate the soft error rate in the natural world before operation
    • Autonomously recovers from soft errors, minimizing impact on communication services and maintenance, by applying soft error countermeasures in the event that a soft error does occur
    • Can check operation when a soft error occurs

    Use Scenes

    • Apply to development process of electronic equipment that must be highly reliable
    • Apply to factor analysis of unexplained failures occurring during operation
    • Confirm effects of soft error countermeasures
    • Apply to software error tolerance evaluation of electronic equipment set to be introduced

    Explanatory Chart

    Technical Explanation

    In recent years, semiconductor devices have come to use more highly integrated circuits and be further miniaturized, leading to greater potential for soft errors. Therefore, it is important to design communication devices assuming that soft errors will occur. Effective countermeasures against such software errors include a bit error correction function called ECC (Error Check and Correct Memory), or making the device reset autonomously when a soft error is detected. However, if countermeasures are taken to excess in areas which have a low rate of soft errors, it will increase the cost of communication equipment. For this reason, it is necessary to track the quality level of communication service provided and number of devices to be installed, set the target quality level for soft errors, and design software countermeasures accordingly. Using an accelerator-driven neutron source, it is possible to recreate soft errors at low cost and confirm countermeasures, in order to reliably evaluate software countermeasures. NTT is working to improve communication service quality by designing communication devices accounting for soft errors.

    Department in charge

    NTT Network Technology Laboratories - Environmental Technology and Management Project

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