MIM Capacitors Research Articles

Fabrication and electrical properties of flexible polymer-based MIM capacitors of high-k nanolaminate dielectrics of HfO2–SnO2–TiO2 with ultrathin Al2O3 insertion layer by plasma-enhanced atomic layer deposition

Abstract Flexible metal–insulator–metal (MIM) capacitors of high-k nanolaminate HfO2–SnO2–TiO2 thin films were fabricated on several polymer substrates of polyethylene terephthalate, polyimide and epoxy resin at 80 °C by plasma-enhanced atomic layer deposition. The electrical properties were optimized by adjusting the sub-cycle ratio of Hf: Sn: Ti to 6: 5: 4. In order to reduce the leakage current density of flexible capacitors, the ultrathin Al2O3 layer varying from 0.5 to 1.5 nm was inserted to form Al2O3/HfO2–SnO2–TiO2/Al2O3 stacking capacitors. The effect of the Al2O3 insertion layer thickness and the super-cycle number of HfO2–SnO2–TiO2 on the capacitance density, leakage, and quadratic voltage linearity was investigated. Under optimal processing, flexible MIM capacitors could stand 40 000 bending cycles at curvature radius of 8.2 mm, indicative of better electrical stability. Moreover, compared with the polymer-based HfO2–SnO2–TiO2 capacitors, the introduction of 1 nm Al2O3 ultrathin layer greatly decreases the leakage current density by 4 orders of magnitude (10−8 A cm−2) with relative lower voltage linearity (350–540 ppm V−2), but the capacitance density also declines (∼3 fF μm−2) simultaneously. Despite this, the method of inserting Al2O3 ultra-thin layer is still an effective method to improve the electrical performances of polymer-based HfO2–SnO2–TiO2 nanolaminate capacitors for flexible electronics.

Enhanced Oxidation Resistance and Interface Stability of Atomic-Layer-Deposited MoNx Electrodes via TiN Passivation for DRAM Cell Capacitor Applications.

The continuous miniaturization of dynamic random-access memory (DRAM) capacitors has amplified the demand for electrode materials featuring specific characteristics, such as low resistivity, high work function, chemical stability, excellent interface quality with high-k dielectrics, and superior mechanical properties. In this study, molybdenum nitride (MoNx) films were deposited using a plasma-enhanced atomic layer deposition (PEALD) employing bis(isopropylcyclopentadienyl)molybdenum(IV) dihydride and NH3 plasma for DRAM capacitor electrode applications. Depending on the deposition temperatures of the PEALD MoNx films ranging from 200 to 400 °C, the Mo/N ratio and crystal structure varied, transitioning from the cubic NaCl-B1-type MoN phase with Mo/N ratio of 1.4 to the cubic γ-Mo2N phase with Mo/N ratio of 1.9. Notably, MoNx films grown at 400 °C exhibited low resistivity (435 μΩ·cm), a high work function (5.28 eV), and superior mechanical hardness (11.3 GPa) compared to ALD TiN films. Despite these excellent properties, the PEALD MoNx electrode demonstrated insufficient chemical stability, particularly in terms of oxidation resistance and interface quality with ALD HfxZr1-xO2 (HZO) films. This resulted in poor morphology and the formation of significant oxygen-deficient HZO layers (such as HfO2-x), leading to considerable degradation in the electrical performance of metal-insulator-metal (MIM) capacitors. To mitigate this issue, a thin (2.5-14 nm) ALD TiN layer was introduced as a passivation layer between the MoNx bottom electrode and HZO dielectric. The TiN-passivated MoNx (TiN/MoNx) electrode showed substantially enhanced oxidation resistance and reduced interfacial reactions with the HZO dielectric. Consequently, MIM capacitors with TiN/MoNx bottom electrodes demonstrated outstanding electrical performance, including excellent dielectric properties, low leakage current density, and high mechanical strength. Hence, this study proposes a promising candidates for storage nodes in the next-generation DRAM capacitors.

MIM Capacitors Featuring Low EOT and Low Leakage Current Density by Nitrogen-Incorporated HfO₂/ZrO₂/HfO₂

MIM Capacitors Featuring Low EOT and Low Leakage Current Density by Nitrogen-Incorporated HfO₂/ZrO₂/HfO₂

Introducing Y2O3 passivation layer for utilizing TiSiN electrode on ZrO2-based metal-insulator-metal capacitor applications

This study investigates the degradation and improvement of the dielectric properties of ZrO2-based metal-insulator-metal (MIM) capacitors using TiSiN electrodes. As dynamic random-access memory (DRAM) design rules scale down, the mechanical properties of TiSiN electrodes provide advantages over conventional TiN, but also introduce challenges due to Si diffusion into ZrO2 films, forming low-dielectric constant (k) Zr-silicate and defect-related dielectric degradation. We evaluate the dielectric properties of ZrO2 films on TiSiN electrodes and identify significant reductions in the dielectric constant and an increase in DC and AC non-linearity due to Zr-silicate formation. To mitigate these problems, a Y2O3 passivation layer is introduced between the TiSiN electrode and ZrO2 dielectric film. Physical and chemical analyses, including X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), confirm that Y2O3 passivation effectively suppresses Si diffusion, preventing formation of Zr silicate, and preserving the high-k tetragonal phase of ZrO2. Electrical measurements show that the Y2O3 layer significantly improves the dielectric constant and reduces non-linearity effects. Notably, even at a reduced ZrO2 thickness of 4 nm, a relatively high k value is maintained with Y2O3 passivation. This study concludes that the Y2O3 passivation layer is indispensable for maintaining high dielectric performance in ZrO2-based MIM capacitors with TiSiN electrodes, ensuring stability and efficiency in advanced DRAM applications.

Towards sustainable, direct printed, organic transistors with biocompatible copolymer gate dielectrics

AbstractWe have investigated the potential of three dielectric materials to meet the future demands of green dielectrics: Polycaprolactone (PCL) thermoplastic, polyvinyl alcohol (PVA)‐carrageenan (CAR) crosslinked biopolymer, and boron nitride nanotubes (BNNTs) as a nano additive in PVA. Metal–insulator–metal (MIM) capacitors and organic thin film transistors (OTFT) were built with bilayer dielectric stacks of PVA‐CAR, PVA‐PCL, and PVA‐BNNT materials to examine their electrical properties. The PVA‐CAR layer uses a cyclic freeze thaw process to crosslink PVA and CAR for superior mechanical and electrical properties to either material alone. The PVA‐CAR MIM capacitors showed a dielectric constant of 23, which was found to be consistent with the extracted OTFT gate dielectric characteristics. Of the OTFT devices tested, PVA‐CAR OTFT showed highest device currents at low applied biases and produced an ON/OFF ratio of 104–105, both values were highest amongst the tested gate dielectrics. This material is therefore extremely promising for green electronics. The PVA‐PCL OTFT had very low leakage current and beneficial hydrophilic properties with comparable electrical properties to the commonly used organic material polytetrafluoroethylene. PVA‐BNNT MIM capacitors showed a low dielectric constant of 0.7, and the high resistivity makes this a promising material for shielding or substrates in high frequency applications. All three materials have the potential to fulfil different niches in a sustainable electronics future.

Effects of plasma oxidation and plasma nitridation on chemical bonding state of AlScN evaluated by AR-HAXPES

The effect of plasma treatment on AlScN films is investigated using angle-resolved hard X-ray photoelectron spectroscopy (HAXPES). As a result, it was observed that the ratio of the oxide component to the nitride component in the AlScN film increased with oxygen plasma treatment. It was also observed that AlScN was less susceptible to oxidation after 1 min of pre-nitridation. Furthermore, the inhibition of oxidation was more pronounced for Sc atoms than for Al atoms. These suggest that the nitridation treatment reduced the number of nitrogen vacancies around Sc atoms. These facts mean that the increase in the on/off ratio of the current in the MIM capacitor can be attributed to the decrease in the number of nitrogen vacancies in the AlScN.

High stability and reliability additively manufactured metal-insulator-metal capacitors for high-temperature applications

Throughout the last few years, there has been a significant increase in demand for high-temperature capacitors due to the rising need for electronics in harsh environments, including aerospace, automotive, and oil and gas industries. With the continued growth of electronics in these environments, there is a need for the development of new materials and manufacturing techniques to drive advances in high temperature capacitor technology. Additive manufacturing is one promising approach for producing electronics that can withstand high temperatures, leading to improved performance and reliability in a wide range of applications. The present work describes the fabrication and testing of MIM (metal-insulator-metal) capacitors at high temperatures using gold as the conductor material. The substrates used in this work is 3D printed Lithoz 350D 99.8% alumina. The work details the fabrication process and evaluates the relative permittivity and the dielectric loss of high-temperature dielectric material at temperatures up to 800°C. The adhesion strength at the interfaces is examined before and after aging for up to 250 hours at temperatures as high as 750°C. The leakage current is measured for 100 hours at varying temperatures and the insulation resistance is calculated. Furthermore, the capacitance is monitored during aging at temperatures up to 700°C and frequencies as high as 1 MHz. Finally, the capacitance is measured at room temperature before and after subjecting the capacitors to 100 cycles of thermal cycling at three different temperature ranges. The adhesion between all interfaces of the MIM capacitors is found to remain high even after aging at 700°C, leakage currents are minimal and stable, and the capacitance remained very stable during and after aging and after thermal cycling.

Breakdown voltage and TDDB performance improvement by optimizing the PECVD dielectric film characteristics in MIM capacitors

The dielectric breakdown voltage (BV) and time dependent dielectric breakdown (TDDB) are the most important concerns for device reliability. In this study, the silicon nitride (SiNx) used as metal-insulator-metal (MIM) capacitor dielectric was successfully prepared by a dual-frequency plasma enhanced chemical vapor deposition (PECVD) method. Fourier transform infrared (FTIR) absorption spectra and electrical characterization results suggest that the SiNx film possesses higher dielectric breakdown voltage performance by decreasing SiH4/NH3 gas flow ratio or optimizing the interface layer among multiple layers. Similarly, the TDDB reliability test based on Weibull distribution indicates an increase in failure lifetime of the MIM capacitors by adjusting RF power and NH3 gas flow.

Study on the single-event burnout mechanism of GaN MMIC power amplifiers

In this Letter, a single-event burnout (SEB) mechanism in gallium nitride (GaN) microwave monolithic integrated circuit power amplifiers with a high linear energy transfer of 78.1 MeV·cm2/mg has been investigated in detail. A typical SEB phenomenon was observed. With the aid of photon emission measurements and scanning electron microscopy, it is found that catastrophic burnout occurs in the power-stage GaN high electron mobility transistors (HEMTs) and the metal–insulator–metal (MIM) capacitors, respectively. For the GaN HEMT, the incident heavy ions will generate electron–hole pairs within it, which can gain enough energy with the transverse high electric field. The high-energy electrons will collide with the lattice near the drain electrode and induce significant electron trapping, which will result in a significant longitudinal local electric field. When a critical electric field is achieved, catastrophic burnout occurs. For the MIM capacitor, the burnout is attributed to the single-event dielectric rupture via severe impact ionization or latent tracks when heavy ions strike it.

Novel halogenated cyclopentadienyl hafnium precursor for atomic layer deposition of high-performance HfO2 thin film.

High dielectric constant (high-k) materials play a crucial role in modern electronics, particularly in semiconductor applications such as transistor gate insulators and dielectrics in metal-insulator-metal (MIM) capacitors. However, achieving optimal crystallinity and suppressing interfacial layer formation during deposition processes remain key challenges. To address these challenges, this study introduces a novel approach using atomic layer deposition (ALD) with a new Hf precursor incorporating an iodo ligand. The synthesized precursor, IHf, demonstrates enhanced thermal stability and reactivity, leading to superior film properties. ALD deposition of HfO2 thin films using IHf yields excellent crystallinity and effectively inhibits interfacial layer formation, resulting in enhanced capacitance density and improved leakage current characteristics in MIM capacitors. Notably, IHf-deposited HfO2 films exhibit a significant reduction in leakage current, achieving an equivalent oxide thickness of 1.73 nm at a leakage current density of 7.02 × 10-8 A cm-2 @ +0.8 V. These findings highlight the potential of IHf as a promising precursor for high-performance electronic device fabrication, paving the way for advancements in semiconductor technology.

Ultra-low power 10-bit 50–90 MSps SAR ADCs in 65 nm CMOS for multi-channel ASICs

The design and measurement results of ultra-low power, fast 10-bit Successive Approximation Register (SAR) Analog-to-Digital Converter (ADC) prototypes in 65 nm CMOS technology are presented. Eight prototype ADCs were designed using two different switching schemes of capacitive Digital-to-Analog Converter (DAC), based on MIM or MOM capacitors, and controlled by standard or low-power SAR logic. The layout of each ADC prototype is drawn in 60 μm pitch to make it ready for multi-channel implementation. A series of measurements have been made confirming that all prototypes are fully functional, and six of them achieve very good quantitative performance. Five out of eight ADCs show both integral (INL) and differential (DNL) nonlinearity errors below 1 LSB. In dynamic measurements performed at 0.1 Nyquist input frequency, the effective number of bits (ENOB) between 8.9–9.3 was obtained for different ADC prototypes. Standard ADC versions work up to 80–90 MSps with ENOB between 8.9–9.2 bits at the highest sampling rate, while the low-power versions work up to above 50 MSps with ENOB around 9.3 bits at 40 MSps. The power consumption is linear with the sample rate and at 40 MSps it is around 400 μW for the low-power ADCs and just over 500 μW for the standard ADCs. At 80 MSps the standard ADCs consume about 1 mW.

Monolithic Switched-Capacitor DC–DC Converters Using BEOL-Compatible Oxide Power Transistors and Superlattice MIM Capacitors

Monolithic Switched-Capacitor DC–DC Converters Using BEOL-Compatible Oxide Power Transistors and Superlattice MIM Capacitors

The planar anodic Al2O3-ZrO2 nanocomposite capacitor dielectrics for advanced passive device integration

ABSTRACT The need for integrated passive devices (IPDs) emerges from the increasing consumer demand for electronic product miniaturization. Metal-insulator-metal (MIM) capacitors are vital components of IPD systems. Developing new materials and technologies is essential for advancing capacitor characteristics and co-integrating with other electronic passives. Here we present an innovative electrochemical technology joined with the sputter-deposition of Al and Zr layers to synthesize novel planar nanocomposite metal-oxide dielectrics consisting of ZrO2 nanorods self-embedded into the nanoporous Al2O3 matrix such that its pores are entirely filled with zirconium oxide. The technology is utilized in MIM capacitors characterized by modern surface and interface analysis techniques and electrical measurements. In the 95–480 nm thickness range, the best-achieved MIM device characteristics are the one-layer capacitance density of 112 nF·cm−2, the loss tangent of 4·10−3 at frequencies up to 1 MHz, the leakage current density of 40 pA·cm−2, the breakdown field strength of up to 10 MV·cm−1, the energy density of 100 J·cm−3, the quadratic voltage coefficient of capacitance of 4 ppm·V−2, and the temperature coefficient of capacitance of 480 ppm·K−1 at 293–423 K at 1 MHz. The outstanding performance, stability, and tunable capacitors’ characteristics allow for their application in low-pass filters, coupling/decoupling/bypass circuits, RC oscillators, energy-storage devices, ultrafast charge/discharge units, or high-precision analog-to-digital converters. The capacitor technology based on the non-porous planar anodic-oxide dielectrics complements the electrochemical conception of IPDs that combined, until now, the anodized aluminum interconnection, microresistors, and microinductors, all co-related in one system for use in portable electronic devices.

Study of Nb2O5 High-k Dielectric Material Deposited By Atomic Layer Deposition for Metal-Insulator-Metal Capacitor

Metal-Insulator-Metal (MIM) capacitors are important components in many electronic devices, including memory devices, filters, and oscillators. The performance of these devices depends strongly on the electrical properties of the dielectric layer. The application of new high-k materials can improve the properties of modern capacitors such as leakage current and capacitance density. However, it is necessary to understand the deposition conditions of both electrode and dielectric materials in order to master the dielectric properties in future MIM capacitors.One potentially interesting high-k material is niobium pentoxide (Nb2O5) with a wide band gap (3.6 eV) and high refractive index (n=2.3 @633 nm) deposited by Atomic Layer Deposition (ALD) using niobium (V) ethoxide as niobium precursor at 180°C and H2O as reaction agent and oxygen source. Nb2O5 films were deposited directly on a silicon (Si 100) substrate or on a 10nm of titanium nitride (deposited by ALD on Si substrate, n=1.4@633 nm). The Nb2O5 films were deposited with a good film thickness uniformity on the 6-inches of the wafers with a thickness ranging from 20 to 60 nm on each sample. The deposition was done under a suitable ALD temperature of 200-300 °C. In order to investigate the film growth, structure, morphology and optical properties, the samples were characterized by spectroscopic ellipsometry (SE), scanning electron microscopy (SEM), X-Ray diffraction (XRD) and atomic force microscopy (AFM). The as-deposited films were then annealed in a furnace at temperature ranging from 500 to 650°C under N2 atmosphere.Subsequently, a MIM structure (Al/Nb2O5/TiN) was produced by adding a second aluminum layer deposited at 250°C on a Nb2O5/TiN/Si stack by the sputtering method. The surface of the second electrodes was aimed to have 0.1-1.0 mm2 to confirm the surface dependency of the capacitance value. The electrical properties of Nb2O5 dielectric layer such as dielectric constant, breakdown voltage and leakage current at possible user voltage were measured on this last structure. The low leakage current density is desirable for MIM capacitors as it helps to minimize energy loss and increase the energy storage capabilities of the capacitors. The obtained J-E curve was compared to some electrical conduction mechanisms to identify its electrical conduction behaviors. The barrier height of the F-N tunneling mechanism was determined by fitting the experimental data to the F-N equation. These measurements indicate that the electrical properties of the Nb2O5 material produced by ALD with specific settings are promising for the application in capacitors. These results provide new insight into our understanding of the application of Nb2O5 realized by ALD for the MIM capacitor.

Towards sustainable, solution-processed organic field-effect transistors using cashew gum as the gate dielectric

To realize low-cost, environmentally friendly electronic devices and circuits, there is currently a strong trend to explore plant-based dielectric materials because they can be responsibly sourced from agricultural or forest vegetation, are generally water-soluble, and possess good electrical insulator properties. In this contribution, organic field-effect transistors (OFETs) using a biopolymer dielectric obtained from exudates of Anacardium occidentale Linn. trees, namely, cashew gum (CG), are reported. To characterise the physical and dielectric properties of the gum, thin films and metal-insulator-metal (MIM) capacitors were prepared and characterized. To evaluate the material’s performance in OFETs, bottom-gate top-contact (BGTC) p-channel poly [3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo (3,4-c)pyrrole-1,4-dione) thieno (3,2-b) thiophene]:polymethyl methacrylate (DPPTTT:PMMA) transistors were engineered and studied. The fabricated MIM capacitors display a comparatively high areal capacitance of 260 nF/cm2 at 1 kHz for 130 nm thick films. As a result, the solution-processed DPPTTT:PMMA OFETs favourably operate at 3 V with the average saturation field-effect mobility equal to 0.20 cm2/Vs., threshold voltage around −1.4 V, subthreshold swing in the region of 250 mV/dec, and ON/OFF current ratio well above 103. As such, cashew gum emerges as a promising dielectric for sustainable manufacturing of solution-processed organic FETs.

Construction of ultrahigh capacity density carbon nanotube based MIM capacitor

Energy storage technology is a key for a clean and sustainable energy supply. but their energy density is restricted by surface charge storage. One effective way to enhance the energy density is electrodes nanosizing in constructing MIM capacitor. However, the overall performance of the capacitors is still limited by electrode specific surface area and bonding strength of their electrode nano-templates to the substrate. In this work, the spatial multilayer VCNTs electrode nano-templates were obtained by laser etching assistance, and MIM capacitors were constructed layer-by-layer with SnO2/Al2O3/SnO2 structures as the dielectric capacitor frameworks via ALD. Laser etching is demonstrated on Al substrate, allowing the spatial multilayer growth of VCNTs with ultrahigh electrode area. Laser etching also introduces an Al2O3 buffer layer, which induces VCNTs in-situ growth during CVD and ensures bonding strength to Al substrate. Moreover, the VCNTs facilitates more coverage by dielectric during ALD, thus reducing the micro-short circuits risk for capacitors. Impressively, the fabricated MIM capacitors have high planar capacity density (0.47∼1.92 mF/cm2) with a low leakage characteristic (5.7 × 10−7 A/cm2) at 1V, which could reach a high energy density (26 µWh/cm2) and power density (104 W/cm2), as well as excellent performance stability under atmospheric and water environments. This work shows a promising strategy for developing new energy storage devices with both high energy and power density, and it has important guiding significance for the electrode nano-templates materials design and preparation of energy storage devices.

Flyback Micro-Converter Design with an Integrated Octagonal Micro-Transformer for DC-DC Conversion

The work presented in this paper concerns the design of an integrated flyback DC-DC micro-converter operating at high frequencies. The flyback converter consists of only one transformer. The integrated micro-transformer in the flyback micro-converter is composed of two planar stacked coils with spiral octagonal geometry. Basing on Mohan’s method, the geometrical parameters are evaluated. The different parasitic effects created in the stacked layers are grouped perfectly in the equivalent electrical circuit that summarizes all parasitic effects. The integrated micro-transformer is characterized by scattering parameters extraction. The thermal and electromagnetic effects generated in the micro-transformer are illustrated, using finite elements method on COMSOL Multiphysics 5.3 software. To validate the electrical model, the simulation of the flyback micro-converter containing the equivalent electrical circuit of the micro-transformer is established, using PSIM 9.0 software. The gap between the coils is considered as an integrated MIM capacitor created at high frequencies leads to create a low pass micro-filter with the secondary coil.

A study of field emission current in MEMS capacitors with bottom electrode covered by dielectric film

The potential distribution in a MEMS capacitor with a thin dielectric film on the bottom electrode and under the presence of field emission leakage current is presented for the first time. The paper also demonstrated the build-up of dielectric charging during this process. The investigation is based on obtaining current-voltage characteristics in clockwise and counter clockwise loops and analyzing the transport mechanisms in MIM capacitors. Same procedure is applied to monitor the dielectric charging build-up during field emission in MEMS capacitors. The data of pristine current-voltage characteristics in both MIM and MEMS are used to determine the Voltage drops across the dielectric film and the gap as well as their dependence on the flowing current.

Fabricate and Characterization of SrTiO3-based MIM capacitors

Fabricate and Characterization of SrTiO3-based MIM capacitors

Atomic layer deposition-processed laminated In2O3:V2O5 nanocompounds: Versatile electrode platforms for high-performance organic photovoltaics and capacitor devices

Despite considerable advancements in transparent conductive electrodes (TCEs), their widespread use in energy storage and conversion devices remains limited. This is primarily attributable to factors such as the work function (WF), surface roughness, and charge mobility limitations. These challenges necessitate comprehensive solutions and innovative approaches to utilize TCEs for energy-related applications. Herein, In2O3:V2O5 nanocompound TCEs were fabricated with excellent transmittance (∼ 90%), high WF (5.33 eV), and large mobility (52.1 cm2/V·s) using atomic layer deposition. The performance of the In2O3:V2O5 nanocompound TCE was evaluated in organic photovoltaics (OPVs) and metal-insulator-metal (MIM) capacitors. In OPVs based on the PM6:Y6 active layer, a low surface roughness and suitable energy level alignment of In2O3:V2O5 nanocompound TCEs with the active layer eliminate the requirement of a hole-transport layer (HTL), resulting in an efficiency of 16.3% and an excellent fill-factor of 71.0% in HTL-free OPVs under simulated 1-sun illumination. Moreover, in MIM capacitor devices that employ the TiO2 dielectric, In2O3:V2O5 nanocompound TCEs exhibit a significantly lower leakage current (> 1800 times) and improved capacitance (2.5 times) compared with those of conventional TiN electrode-based capacitors. The dual functionality of the proposed In2O3:V2O5 nanocompound TCEs validates their potential for use in several optoelectronic devices.