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One of the most attractive types of novel nonvolatile memory concepts is resistive random access memory (ReRAM) based on a reversible (“soft”) dielectric breakdown effect. The interest is caused by combining simple architecture with promising performance: excellent scalability, nanosecond speed, long data retention, and low power consumption. However, the commercialization of this type of memory is retarded mainly due to serious drawbacks: high cell-to-cell variability of switching parameters and limited endurance related to the ionic origin of resistive switching effect coupled with the problem of voltage overshooting. In particular, these issues complicate the examination of test samples because during the lifespan of memory cells, and the permanent reselection of test switching parameters is required. This challenge can be overcome by developing a measurement technique that combines careful testing of every single structure and the ability to test a large number of test structures. As such a technique, we propose an automated testing algorithm that automatically avoids voltage overshooting and provides an effective way of characterization of cell-to-cell and cycle-to-cycle variability. It includes all stages of ReRAM cell operation, specifically electroforming, dc switching, and endurance testing in the pulsed mode. The developed technique allows on-the-fly restoring of the memory window in case of its degradation, making it possible to better understand the potential of the material stacks of the memory cell.

The selectivity of the reactive ion etching of functional materials included in the device structures of nanoelectronics with respect to the mask of a negative e-beam resist based on hydrogen-silsesquioxane (HSQ) is studied. The formation of nanostructures with sub-50-nm critical dimensions under the HSQ mask is studied for a number of materials: monocrystalline silicon, metallic Ta layers, dielectric SiO2 layers, Al2O3, HfO2, Si3N4, and low-k porous dielectric based on organosilicate glass (OSG) on silicon substrates. It is established that HSQ resist masks can be used to manufacture prototypes of micro- and nanoelectronic devices with topological dimensions up to 10 nanometers using a wide range of materials, including creating structures with relatively high aspect ratios with an absolute thickness of the layers of functional materials of tens of nanometers.

Resistive switching (RS) device behavior is highly dependent on both insulator and electrode material properties. In particular, the bottom electrode (BE) surface morphology can strongly affect RS characteristics. In this work, Ru films with different thicknesses grown on a TiN layer by radical-enhanced atomic layer deposition (REALD) are used as an inert BE in TaOx-based RS structures. The REALD Ru surface roughness is found to increase by more than 1 order of magnitude with the increase in the reaction cycle number. Simultaneously, a wide range of RS parameters, such as switching voltage, resistance both in low and high resistance states, endurance, and so forth, monotonically change. A simplified model is proposed to explain the linkage between RS properties and roughness of the Ru surface. The field distribution was simulated based on the observed surface morphologies, and the resulting conducting filament formation was anticipated based on the local field enhancement. Conductive atomic force microscopy confirmed the theoretical expectations.

The selective pore sealing of porous organosilica glass (OSG k = 2.4) dielectrics by self-assembled monolayers (SAM) is studied, using three precursors: (3-trimethoxysilylpropyl) diethylenetriamine (DETA), 3-aminopropyltrimethoxysilane (APTMS) and trimethylmethoxysilane (TMMS), combined with a citric-acid based metal surface cleaning. The sealing effectiveness of the SAM films derived from amino-containing precursors is demonstrated. The selectivity of the SAM grafting to the dielectric surface with respect to the copper surface is investigated. Post-SAM deposition cleaning in citric acid-based solution leads to desorption of the amino-containing precursors from the copper surface while the low-k surface remains partially covered and sealed. On copper, the SAM cleaning process occurs through interface copper oxide removal, by means of a lift-off mechanisms.

We describe a bipolar memristor in the Verilog-A language. The proposed model concepts take into account the following parameter deviations in the memristor switching between conduction states: the variation of the conduction parameters in the highly resistive and low-resistance state, the switching threshold variations, and the variation of the number of switching cycles.

Frontiers in neuroscience 14, 94 (2020). doi:10.3389/fnins.2020.00094, The development of highly integrated electrophysiological devices working in directcontact with living neuron tissue opens new exciting prospects in the fields ofneurophysiology and medicine, but imposes tight requirements on the power dissipatedby electronics. On-chip preprocessing of neuronal signals can substantially decrease thepower dissipated by external data interfaces, and the addition of embedded non-volatilememory would significantly improve the performance of a co-processor in real-timeprocessing of the incoming information stream from the neuron tissue. Here, we evaluatethe parameters of TaOx-based resistive switching (RS) memory devices produced bymagnetron sputtering technique and integrated with the 180-nm CMOS field-effecttransistors as possible candidates for on-chip memory in the hybrid neurointerfaceunder development. The electrical parameters of the optimized one-transistor–oneresistor (1T-1R) devices, such as the switching voltage (approx. ±1 V), uniformity ofthe Roff/Ron ratio (∼10), read/write speed (, Published by Frontiers Research Foundation, Lausanne

The processes of plasma etching of stack layers to form a structure of a metal gate of a nanoscale transistor with a dielectric with a high level of dielectric permittivity (HkMG) are investigated. A resist mask formed by fine-resolution electron-beam lithography is used in the etching. The plasma etching of the stack’s layers is carried out in one technological etching cycle without a vacuum break. The sequential anisotropic etching process of the stack of polysilicon, tantalum nitride, and hafnium nitride, as well as the etching process of the gate insulator based on hafnium oxide with a high degree of selectivity in relation to the underlying crystalline silicon, which guarantees the complete removal of the layer of hafnium oxide and the minimal loss of the silicon layer (not more than 0.5 nm), is investigated.

The electromigration influence on main characteristics of planar electrochemical systems with difference parameters was studied. The transporting processes are simulated, current-voltage characteristic, transfer function and THD were calculated, and quantitative estimates of the magnitude of the asymmetric electromigration flow and its effect on the nonlinearity coefficient of the system are obtained.

The issues related to the integration of functional elements of ReRAM memory based on resistive Pt/HfO2/TiN structures with transistors fabricated by CMOS technology (0.18 μm node) are discussed when placing the memory cells in metallization layers. It is shown that the formation of a ReRAM stack can be organized as the “back end of line” (BEOL) process. The possibility is demonstrated of writing information in fabricated 1T-1R cells at the given levels of current determined by the voltage on the transistor, which allows one to choose the required values of resistance for the ON and OFF states. The presence of a transistor makes it possible to limit the power that is scattered in a resistance-switchable structure, and makes its parameters virtually insensitive to changes in the voltage of writing. The latter circumstance makes it possible to use the same recording voltage for all devices, which makes the problem of reproducing the values for different cells in an array less acute.

The structural and electrical properties of materials based on hafnium oxide grown by atomic layer deposition (ALD) are analyzed. The possibility and prospects of the use of their nanoscale films in nonvolatile memory are considered. The possibility of scaling Ferroelectric random access memory (FRAM) to subμm dimensions while preserving the ferroelectric properties is shown.

The losses in optical components are the key obstacle in development of photonic integrated circuits (PIC). This makes the developers to include additional signal gain elements into the optical scheme. One of the major and optimizable factors of signal loss is the sidewall roughness of the optical components. After analysis of factors causing the line-edge roughness (LER), we developed the basic model of the roughness emerging process during forming of photolithography nanostructures. We proposed an approach to optimize the photolithography process in order to minimize the optical losses in fabricated optical structures. The software complex on the basis of this approach is currently under development.

A nanocarbon-emitter technology for integrated field-emission elements has been developed. The modes in which various carbon film structures of diamond, graphite, and graphene-like types are produced were determined. The low-temperature method of obtaining ultradispersed diamonds was examined. It is shown that the high-emission properties of nanodiamond-graphite emitters result from the self-organization of diamond nanocrystals in a graphite film in the course of deposition from ethanol vapor at low pressure with the use of a strongly nonequilibrium microwave plasma. The following parameters of integrated field-emission diodes were obtained: emission threshold of 2.5 V/μm and emission current density of 1.75 A/cm2. The highest current density of more than 20 A/cm2 was obtained in a study of blade-type emitters.

The memristor metal-oxide-metal structures involving the layers of stoichiometric hafnia and nonstoichiometric hafnia doped with aluminum, as well as the metal-oxide-extracting metal layer structures involving the layers of hafnia and titanium, are fabricated. The oxide layers are coated using the atomic layer deposition. The resistive switching parameters of the structures are determined.

A nonvolatile memory cell prototype based on the effect of resistive switching in thin Hf x Al1 − x O y oxide films grown by atomic layer deposition (ALD) with a Al depth-graded profile has been developed. This prototype imitates the arrangement of memory cells between the metallization layers of integral circuits. The obtained results are much superior to the parameters of conventional flash memory cells in increasing the reset speed and decreasing the reset voltage.

Planar electrochemical systems are very perspective to build modern motion and pressure sensors. Planar microelectronic technology is successfully used for electrochemical transducer of motion parameters. These systems are characterized by an exceptionally high sensitivity towards mechanic exposure due to high rate of conversion of the mechanic signal to electric current. In this work, we have developed a mathematical model of this planar electrochemical system, which detects the mechanical signals. We simulate the processes of mass and charge transfer in planar electrochemical transducer and calculated its transfer function with different geometrical parameters of the system.

Cellular-automata model of oxygen plasma influence on the integral properties of porous low-K dielectric is studied. The present work investigates the imitative simulation of this process. In our model we consider one isolated pore, which is simulated by cylinder with length L=200 nm and radius 1 nm ignoring the curvature factor. The simulation was performed for 2 million automata steps that correspond to 2 seconds in the real process time. Extrapolating the data to the longer time shows that more and more •CH 3 groups will be replaced by the •OH groups, and over time almost all methyl groups will leave the pore surface (there is not more than 20% of the initial methyl groups amount on the first low-K dielectric 40nm after 2 seconds simulation).

We have developed the new technology for production of sensitive modules for electrochemical sensors of pressure and acceleration. The technology is applicable for mass production and scalable for high-volume production. In this work we demonstrate the new sensing module for electrochemical motion sensors, and its possibility of applying in geophones. We fabricated prototypes of electrochemical planar transducer chips, produced a laboratory prototype of a geophone based on our planar transducer chip, and tested them. This paper presents the preliminary results of the tests.

The aim of the work was to study the effect of various microelectronic structural and technological implementations to improve the field emission properties of the nano-carbon emitters. The field emission properties of vacuum diodes with nanodiamond-graphite emitters of different geometric shapes was researched. The nanodiamond-graphite layers deposition were carried out from ethanol vapor at low pressure using microwave plasma. Three series of experiments were studied. Researching of emission currents with flat cathodes on silicon wafer coated by nanodiamond-graphite layer were done in first series of experiments. In the second series of experiments, the electrical parameters of integrated field emission diodes with flat nanodiamond-graphite emitters was studied. In the third series of experiments, the electrical parameters of field emission with flat nanodiamond-graphite formed as a micro-sized needles or blades were studied. Vacuum emission studies were done at temperature 300K and pressure 1 × 10 -6 Torr. Threshold voltage from10-50V per micron and current density about 0.2 A/cm 2 were obtained in the first series of experiments. In the second and third series of experiments, a threshold voltage from 1 to 10V/ μm and current density of 1.75 A/cm 2 were displayed. The greatest current density more than 20 A/cm 2 was obtained using a blade-type emitter.

Polymer grafting was studied in porous low-k SiCOH films as a protection against plasma damage. Pores of low-k films were covered by a plasma damage management polymer. A multistep deposition approach was applied to increase the polymer layer thickness that helped avoid pore stuffing, nonuniform deposition and polymer overburden. To study polymer protection, low-k films were exposed to F radicals and VUV photons, separately and simultaneously, at temperatures from −45 °C to +10 °C. Effective polymer protection at room temperatures was demonstrated. Lowering the temperature decreases degradation by F radicals while VUV damage, which is temperature independent, became dominant. Low-k damage protection was also significant under simultaneous exposure to F radicals and VUV photons. In the tested temperature range damage under simultaneous exposure to F radicals and VUV photons was higher than the sum of separate F and VUV damage due to a synergistic effect. To decrease the material k-value after etching, the polymer was removed from the pore walls using UV cure. It was shown that almost complete polymer removal was achieved after UV treatment. The described approach was applied to low-k etching in RF CCP CF4, CF4/Ar plasmas and exposure to Ar plasma. Significant improvement of the film k-value after the plasma treatment was confirmed.

A diffraction-ellipsometry method is described for determining step height on a homogeneous material or an arbitrary multilayer. It consists in measuring ellipsometric parameters for individual beams reflected from the respective sides of a step and for a combined beam obtained from the two reflected beams, with the step height calculated from the measured data by a specially designed algorithm. With multilayers, the ellipsometric parameters are also to be measured with the specimen immersed in a suitable liquid. Beam combining is performed by a special device, which is also designed to change the amplitude and phase of each beam by specific amounts. Care is taken to make the respective wave fronts of the reflected beams parallel on the photodetector.

A method of SEM linear measurement is proposed in which the reference marker displayed on the screen is used as a standard. The method works in a wide range of magnification without magnification calibration. Calibration of the marker against the MShPS-2.0K linear standard is described. The characteristics of the marker are investigated as functions of scanning range and declared effective marker length for the CamScan S-4 model of SEM. The maximum allowable calibration interval is determined for this SEM.

Linear standards for the calibration of SEMs and AFMs are reviewed. Requirements to a surface pattern designed to serve as a universal standard for the above purpose are defined. A trapezoidal pitch structure is proposed, in which the sidewalls of basic units essentially make a large angle with the normal to the surface. Its uses in SEM–AFM dimensional metrology are considered. A new, universal standard implementing the structure is described. Its certification is briefly reported. SEM and AFM experiments with the standard are presented.

A geometric model of a scanning force microscope (atomic force microscope) (SFM) cantilever with micro- and nanostructures is considered. A linear gauge is proposed for SFM calibration and for definition of the SFM probe parameters. SEM and SFM methods of measuring submicrometer dimensions of relief structures are compared.

Practically, all resonant-tunnelling devices contain as their important part an undoped spacer layer separating a heavily-doped layer from the barrier. Including the spacer layer into the structure has several good points. It permits, for instance, to decrease the device capacitance, to prevent impurity diffusion into the active part of the device, to eliminate an effect of the long-range Coulomb potential on the tunnelling, and thus, to improve the current-voltage characteristics of the device. however, a thick spacer layer is also a drawback which can essentially affect the transport properties in the injector. Actually, owing to a light doping in a close vicinity of the emitter barrier, an applied bias voltage creates an accumulation layer. Generally, the presence of the accumulation layer makes the tunnelling dynamics worse, because the recharging processes which occur in this layer are slow as compared with the tunnelling time thus giving rise to an extra frequency cut-off. The physical processes occurring in the injector part of device are still of interest as being of a large significance for the device operation. In this work we grew a structure whose composition was chosen so as to obtain the flat band regime in the emitter spacer under resonance condition. High