Soft Error Testing Technology to Support Highly Digitized Social InfrastructureNTT Space Environment and Energy Laboratories

In recent years, the increased functionality and performance of communications equipment has led to increased integration of semiconductor devices, increasing the risk of soft errors (temporary memory errors) due to cosmic ray-induced neutrons. NTT understands that soft errors will occur, and established countermeasure design methods for communication equipment that do not affect communication services or maintenance even if soft errors occur, along with reproduction test technology that can confirm operations and countermeasure effects when soft errors occur.

In recent years, the number of soft errors in communication equipment caused by cosmic ray-induced neutrons has been increasing. A soft error is a temporary failure that is addressed by restarting the device or overwriting data, unlike a hard error that causes the device to fail permanently. If a soft error occurs on communication equipment, it can trigger various failure modes and affect communication service. Communication equipment is designed with these failures in mind so that communication services will not be affected, but it's not possible to verify this because it's difficult to reproduce soft errors. This sometimes results in unexpected behavior.

• Reproduces soft errors instantly by irradiating 100,000,000x the neutrons found in nature
• Can evaluate rate of soft errors occurring in nature prior to operation
• Applies soft error countermeasures to automatically recover from soft errors and minimize the impact on of soft errors on communication services and maintenance
• Allows operations checks when soft errors occur

• Development process of electronic equipment which requires high reliability
• Factor analysis of unexplained failures that occur during operation
• Verification of effectiveness of soft error countermeasures
• Evaluation of soft error resistance of electronic devices that will be installed

In recent years, soft errors have been rapidly increasing due to the high density and refinement of semiconductor devices. Therefore, it is important to design communication equipment assuming the occurrence of soft errors. While such soft errors can be addressed using a bit error correction feature called ECC (error check and correct memory), or by designing devices to automatically reset when a soft error is detected, but implementing excessive measures at low soft error rates can increase the cost of communications equipment. It is necessary to set quality level goals for soft errors, and design appropriate soft error countermeasures based on an understanding of the quality level of communication services provided, and how many units will be installed. In addition, the use of accelerator-driven neutrons provides a low-cost method of reproducing soft errors to verify countermeasures, which ensures that soft error countermeasures are properly evaluated. In this way, NTT is working to improve the quality of its communication services by designing communications equipment that anticipates soft errors.

NTT Space Environment and Energy Laboratories - Resilient Environmental Adaptation Research Project