Feng Yan, Technology Daily Reporter, Wang Chun

Fudan University has made a key breakthrough in the field of integrated circuits! The "Xiaoyao" picosecond flash memory device developed by the team led by Zhou Peng/Liu Chunsen can be erased and written at a speed of 400 picoseconds, which is equivalent to performing 2.5 billion operations per second. It is the fastest semiconductor charge storage device currently known to humans. On April 16th, Beijing time, relevant research results were published in the international journal Nature.

The charge storage device is the foundation of the booming information technology industry. Charges can drive changes in current within electronic devices at an astonishing speed with excellent reliability, enabling efficient data transmission and precise processing through complex combinations of electrical signals.

The "memory" and "hard disk" in personal computers are two typical representatives of charge storage devices. "Memory" - static random access memory (SRAM) and dynamic random access memory (DRAM) have a limit of less than 1 nanosecond for access speed, approximately equivalent to three times the speed of transistor switching, representing the highest level of information access speed today. However, after power-off, the stored data will be lost, and this "volatile" characteristic requires it to consume a certain amount of energy to function, limiting its application under low-power conditions.

In contrast, the "hard disk" - non-volatile memory represented by flash memory, does not lose data after power-off and has the advantage of low power consumption. However, due to its programming speed assisted by electric fields being far lower than the speed of transistor switching, it struggles to meet the requirements of high-speed access to large amounts of data, such as AI computing scenarios.

Therefore, in response to the computational power and energy efficiency requirements of AI computing, the storage technology urgently needs a breakthrough, and the breakthrough point lies in solving the most critical fundamental scientific problem in the field of integrated circuits: surpassing the non-volatile access speed limit of information, i.e., not losing data when powered off while achieving faster access.

According to reports, the research team began focusing on breaking through the limits of charge storage speed since 2015. "The hardest part is breaking through mental stereotypes," said Professor Zhou Peng. "At first, there is always a feeling that higher access speed means data must be lost when powered off, making it difficult to change the perspective of thinking."

By breaking through the bottleneck of basic theory, the research team discovered a "super injection" mechanism for charge storage. Liu Chunsen introduced that the existing hard disk flash memory mechanism stores signals by injecting charges into the channel of the material, with the fastest injection speed occurring at around 5 volts. When the voltage is too high or too low, the speed slows down. "Our achievement starts from the technical foundation, proposes theoretical innovation, and adjusts the physical mechanism of the material to achieve 'the higher the voltage, the faster the storage' 'unlimited' super-injection storage, enhancing non-volatile storage speed to the theoretical limit." Based on this, the research team redefined the boundaries of existing storage technologies and successfully developed the "Xiaoyao" picosecond flash memory device, whose performance surpasses the world's fastest volatile storage SRAM technology at the same technological node.

It is reported that flash memory, as the most cost-effective and widely used storage device, has always been the cornerstone of international tech giants' technological layout. The above results not only have the potential to change the global storage technology landscape, promote industrial upgrading, create new application scenarios, but also provide strong support for China's technical leadership in related fields. Liu Chunsen revealed that related products are currently undergoing small-scale mass production.

Photo credit: Fudan University

Poster design: Yang Kai, Song Ci

Editor: Song Ci

Reviewer: Zhu Li

Original article: https://www.toutiao.com/article/7494103996857319986/

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