ReRAM is usually developed by memristor, in which the oxygen vacancies (oxygenvacancy) transferred in the dielectric layer change the resistance of the dielectric to '1' and '0'". In addition to MIPT, researchers from 4DSMemoryLtd., CrossbarInc., HPInc., KnowmInc., and the Rice University in Dezhou (RiceUniversity) created prototypes for ReRAM. "We need to not only have oxygen vacancies in the dielectric layer, but also have to be tested for 3DReRAM," says MIPT scientist KonstantinEgorov". To this end, MIPT researchers employed the method of observing the electron state in the gap of the dielectric layer where oxygen vacancies were present. Egorov said: "in order to study on the growth process of oxygen vacancies formed in tantalum oxide films, we use an integrated growth of PEALD (plasma assisted atomic layer deposition (X) and XPS ray photoelectron spectrometer) (vacuum tube connected to the chamber of the experimental cluster). The cluster allows us to grow and study sedimentary layers without disrupting the vacuum." "This is important because once the sample is removed from the vacuum, the dielectric nano layer is oxidized on its surface, leading to the disappearance of oxygen vacancies," he stressed." Any semiconductor research laboratory can construct this unique atomic layer deposition (ALD) cluster by connecting the PEALD and XPS chambers, and then adding an automatic manipulator to transfer wafers between the chambers. In addition to the sample test wafers, this cluster is not needed in mass production. However, a assembly line must be established to compensate for the slow growth rate of the ALD film. If these studies are successful, MIPT claims that the resulting ReRAM can stack vertically and achieve a general-purpose memory that can overcome 3Dflash limitations; for now, 3Dflash is limited to 64 layers. Although the growth of ALD is slow, it can realize conformal coating of 3D structure, instead of the deposition technology of nano film used by MIPT and other research laboratories. The key difference is that ALD sequentially exposes the substrate to precursor material and reactant material and depends on the chemical reaction between the two to produce an active layer. The MIPT technique also uses chemical molecules that are linked to the metal precursor to accelerate chemical reactions, but must be removed before the active layer for the element. "The deposition of oxygen deficient films requires finding the correct reactants to remove the ligands contained in the metal precursors and to control the oxygen content of the coating," said AndreyMarkeev, chief researcher at MIPT. Therefore, after many experiments, we successfully used oxygen containing tantalum precursors and plasma excited hydrogen reactants." Next, the researchers plan to optimize the process and increase the speed of the ALD to mass production of the 3DReRAM. MIPT's research funding was provided by the Russian Science Foundation (RSF) and MIPT. This study details have been published in the "ACS application materials and interface" (ACSAppliedMaterials&Interfaces) "in the Journal of oxygen vacancies plasma assisted atomic layer deposition TaOx film control, realize the application of variable resistance switching memory" in an article.
