The creation and development of devices for non-volatile storage of digital data has been going on for many decades. A real breakthrough a little less than 20 years ago was made by NAND memory, although its development started 20 years earlier. Today, about half a century after the start of large-scale research, the start of production and constant efforts to improve NAND, this type of memory is close to exhausting its development potential. It is necessary to lay the foundation for the transition to another memory cell with better energy, speed and other characteristics. In the long term, a ferroelectric memory of a new type can become such a memory.
Ferroelectrics (the term ferroelectrics is used in foreign literature) are dielectrics that have a memory of the applied electric field or, in other words, are characterized by residual charge polarization. Ferroelectric memory is nothing new. The challenge was to scale down ferroelectric cells to the nanoscale.
Three years ago, scientists at MIPT technology for manufacturing thin-film material for ferroelectric memory based on hafnium oxide (HfO2). This is also not a unique material. This dielectric has been used for several five years in a row to make metal gate transistors in processors and other digital logic. On the basis of alloyed polycrystalline films of hafnium and zirconium oxides with a thickness of 2,5 nm proposed at the Moscow Institute of Physics and Technology, it was possible to create transitions with ferroelectric properties.
In order for ferroelectric capacitors (as they were called at MIPT) to be used as memory cells, it is necessary to achieve the maximum possible polarization, which requires a detailed study of the physical processes in the nanolayer. In particular, to get an idea about the distribution of the electric potential inside the layer when voltage is applied. Until recently, scientists could rely only on the mathematical apparatus to describe the phenomenon, and only now a technique has been implemented that literally managed to look inside the material in the process of the phenomenon.
The proposed technique, which is based on high-energy X-ray photoelectron spectroscopy, could only be implemented on a special facility (accelerator-synchrotrons). This one is located in Hamburg (Germany). All experiments with "ferroelectric capacitors" based on hafnium oxide manufactured at MIPT took place in Germany. An article about the work carried out was published in .
“The ferroelectric capacitors created in our laboratory, if they are used for the industrial production of non-volatile memory cells, are capable of providing 1010 rewriting cycles - one hundred thousand times more than modern computer flash drives allow,” says Andrey Zenkevich, one of the authors of the work, head of the laboratory of functional materials and devices for nanoelectronics MIPT. Thus, one more step has been taken towards a new memory, although there are still many, many more steps to be taken.
Source: 3dnews.ru