A Japanese research group developed a technology to realize a storage device that can store data for more than 1,000 years and has a recording density equivalent to that of an HDD.
The group, which is led by Makoto Nagata and Noriyuki Miura at Kobe University, announced the "eternal storage" technology at ISSCC 2017 (lecture number: 15.8).
With the new technology, data are recorded based on the existence of a metal nanodot at the intersection point of word and bit lines formed in a silicon (Si) wafer. The capacity between word and bit lines changes depending on the existence of a metal nanodot. Based on the difference in capacity, "0" or "1" is assigned. When there is a metal nanodot on the word line, the value is "1" and vice versa.
Because data are recorded by using metal nanodots, the new technology is resistant to aged deterioration. When a wafer in which data are recorded (with metal nanodots) is sealed with an insulating film, the data can be stored for a long period of time. The research group expects that, after the sealing, power will be wirelessly supplied to the device and data will be wirelessly read out.
In other words, a metal nanodot formed on a word line is a via that is shortened so as not to connect word and bit lines, the group said. Therefore, it is easy to realize a multi-layer structure like the interconnection of a semiconductor device. Also, semiconductor processes can be applied. Unlike general processes, there is a process of using a mask to etch and shorten vias.
New method developed for data writing
According to the research group, data reading with the new technology is easy because a mutual capacitance sensor like a sensor used for a touch sensor can be used to read out data. On the other hand, data writing requires some techniques.