Improved properties of MIM capacitors using ALD Al2O3 by multi-temperature technique

Characterization of aluminum oxide thin films obtained by chemical solution deposition and annealing for metal–insulator–metal dielectric capacitor applications

Abstract: A novel chemical formulation is presented that enables the chemical solution deposition of aluminum hydroxide thin films, which transforms into aluminum oxide through subsequent annealing. The proposed method represents a faster and more economical alternative for aluminum oxide thin film deposition that can be used in metal-insulator-metal (MIM) dielectric capacitor applications. The film properties were studied in detail via X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and optical spectroscopy. It is demonstrated that the obtained thin films present high optical quality, low-crystalline domains, and oxygen vacancies. The films that were obtained for a 30 min deposition time show a suitable surface morphology and thickness, determined by atomic force microscopy and a cross-section from scanning electron microscopy, of a dielectric layer which was used to fabricate a MIM device. Using capacitance-voltage and current-voltage characterizations on that device, a low leakage current in the 10−4 A/cm2 range and a capacitance of 98 and 48 nF/cm2 were measured. These results indicate that, both aluminum hydroxide and aluminum oxide thin films have dielectric properties that are comparable to those of silicon oxide. Thus, the proposed method allows the deposition of gate dielectric films at low temperatures through a technically simple and scalable process.

Multi-temperature deposition scheme for improved resistive switching behavior of Ti/AlOx/Ti MIM structure

Abstract: Atomic layer deposited AlO x based resistive random access memories were fabricated with a new multi-temperature deposition (MTD) scheme, where a 40 nm thick AlO x film was deposited with temperature-thickness sequence of 150 °C (10 nm)/80 °C (20 nm)/150 °C (10 nm). Electrical characteristics of thus fabricated devices demonstrate improved bipolar resistive switching behavior with lower set and reset voltages of 0.65 V and − 1.15 V respectively, decent repeatability of 75 cycles, reliable data retention upto 10 3 s, small variation of 0.29 V and 0.17 V in set and reset voltages respectively, and symmetric current-voltage curves. The conduction mechanism has been explained as ohmic and space charge limited conduction at lower and higher voltages respectively. Due to different deposition temperature, oxygen vacancy concentration was different in each layer of the MTD film, which led to formation of a conductive filament with nonhomogeneous strength and dimensions across the film. Localization of effective switching phenomenon in the region with weaker conductive filament yielded an improved performance with lower switching voltages in corresponding multi-temperature devices.

The Effect of Different Dielectric Materials in Designing High-Performance Metal-Insulator-Metal (MIM) Capacitors

Abstract: A Metal-Insulator-Metal (MIM) capacitor with high capacitance, high breakdown voltage, and low leakage current is aspired so that the device can be applied in many electronic applications. The most significant factors that affect the MIM capacitor’s performance is the design and the dielectric materials used. In this study, MIM capacitors are simulated using different dielectric materials and different number of dielectric layers from two layers up to seven layers. The effect of the different dielectric constants ( k ) to the performance of the MIM capacitors is also studied, whereas this work investigates the effect of using low- k and high- k dielectric materials. The dielectric materials used in this study with high- k are Al 2 O 3 and HfO 2 , while the low- k dielectric materials are SiO 2 and Si 3 N 4 . The results demonstrate that the dielectric materials with high- k produce the highest capacitance. Results also show that metal-Al 2 O 3 interfaces increase the performance of the MIM capacitors. By increasing the number of dielectric layers to seven stacks, the capacitance and breakdown voltage reach its highest value at 0.39 nF and 240 V, respectively.

Surface-roughness effect on capacitance and leakage current of an insulating film

Abstract: Effects of surface roughness on electrical properties of a thin insulating film capacitor with one smooth electrode plate and one rough electrode plate are investigated. The electrode plate roughness is described in terms of self-affine fractal scaling through the roughness exponent \ensuremath{\alpha}, the root-mean square (rms) roughness amplitude w, and the correlation length \ensuremath{\xi}. The electric field, capacitance, and leakage current show similar qualitative changes with the roughness parameters: they all increase as w increases, and also increase as either \ensuremath{\xi} or \ensuremath{\alpha} decreases.

Atomic layer deposition of zirconium oxide from zirconium tetraiodide, water and hydrogen peroxide

Abstract: Atomic layer deposition of zirconium oxide from zirconium tetraiodide, water and hydrogen peroxide

Implementing ALD Layers in MEMS Processing

Abstract: Layers manufactured by the ALD technique have many interesting applications in microelectromechanical systems (MEMS), for example as protective layers for biocompatible coating, highdielectric-constant layers, or low-temperature conformal insulating layers. Before an ALD process can be successfully implemented in MEMS processing, several practical issues have to be solved, starting from patterning the layers and characterizing their behaviour in various chemical and thermal environments. Stress issues may not be forgotten. We have recently implemented two ALD processes, namely the trimethylaluminium/water process to deposit Al2O3 and the titanium tetrachloride/water process to deposit TiO2 in our MEMS processing line and carried out the necessary characterization, details of which are reported here. For us, ALD has been a truly enabling technology in the processing of a three-dimensional micromechanical compass based on the Lorentz force, where Al2O3 acted as a pinhole-free electrical insulation grown at low temperature.

In situ electric field simulation in metal/insulator/metal capacitors

Abstract: The authors report in this letter the effect of interface topography on metal/insulator/metal (MIM) capacitor electrical properties. This analysis was carried out by numerical simulations of the electric field established in a MIM structure with a 45nm thick Ta2O5 film. The metal/insulator interface profiles have been extracted from transmission electron microscopy micrographs of a fully integrated device. This in situ approach allows direct comparison between electrical properties and numerical simulations performed on the same device. Results show that the bottom electrode’s surface roughness induces a large electric field increase at the interface which could explain MIM capacitor’s asymmetrical electrical behavior.