Contributing to the Solution of Environmental Issues in the Data Society through the Sustainable Reuse of SSDs

As the digital society evolves, the demand for data storage and processing continues to increase dramatically. At the same time, the increasing production and use of electronic devices have led to a rise in electronic waste, which is rapidly becoming a social problem.

According to the Global E-waste Monitor 2024,¹ it is estimated that in 2022, the world generated a staggering 62 million tons of electronic waste, with only 22.3% being properly collected and recycled. Furthermore, it is predicted that by 2030, the amount of electronic waste generated will reach 82 million tons, with the recycling rate falling to 20%.

One of the commonly used data storage devices in PCs and data centers is the NAND flash memory used in SSDs (solid state drives). However, the characteristics of 3D flash memory degrade with repeated data rewriting, eventually leading to its disposal at the end of its useful life. Even before reaching the end of their useful life, SSDs that are no longer used by users are often physically destroyed and disposed of due to the risk of information leakage.

Disposing of SSDs drives up the consumption of scarce resources, including rare metals. Additionally, their manufacturing process requires a significant amount of electricity, increasing CO₂ emissions. As the amount of digital data circulating in the world continues to increase, it is becoming crucial to address these issues.

The "Guidelines for Media Sanitization² issued by the National Institute of Standards and Technology (NIST) in the United States defines appropriate data sanitization methods based on the type of media and the confidentiality of the stored data. It mentions that in some cases, data erasure is more suitable than destruction from an environmental standpoint and when a product is to be reused. It also emphasizes that data sanitization should be assessed as to cost and environmental impact.

In Japan, the Ministry of Internal Affairs and Communications revised its "Guidelines for Information Security Policies in Local Governments" in 2022, shifting from the premise of disposal to the consideration of reuse of storage and other media when they are no longer needed.³

This highlights the importance of considering both information security and environmental considerations in storage usage.

In 2023, Kioxia announced its development of the world's first technology allowing the properties of 3D flash memory to be recovered through heat treatment, enabling their semi-permanent use.⁴ By putting this technology to practical use, Kioxia aims to enhance the potential for SSD reuse, and contribute to the reduction of CO₂ emissions and electronic waste.

When 3D flash memory reaches End Of Life as a result of multiple program/erase cycles, cell characteristics such as cell threshold voltage (Vth) and data retention degrade, and it can no longer meet storage performance requirements. In a world-first, Kioxia has demonstrated that the cell characteristics of 3D flash memory can be recovered to their initial state by applying annealing with specific values programmed in the cell, and that this recovery process can be applied repeatedly.

Kioxia has confirmed that a recovery effect can be achieved at an annealing temperature of around 150°C, enabling recovery not only for flash memory chips and package devices but also for the entire SSD module, including implementation components and controllers.⁵

By significantly extending the lifespan of SSDs through this technology and reducing the level of disposal of SSDs, Kioxia aims to help reduce resource consumption and power consumption, as well as minimize the environmental impact of the digital society.

The Kioxia Group will continue to develop technologies to improve the efficiency of semiconductor resource utilization and link them to new business together with our partners in sustainable memory technology, aiming to help solve global environmental and social issues and to helping more people lead more convenient and comfortable lives.

We have received the following message from our partner company, AOS DATA, Inc., expressing their support for our activities and their willingness to discuss the potential utilization of our technology.