Voltage Coefficient Of Capacitance Research Articles

Bovine Serum Albumin-Based Thin-Film Capacitors for Flexible Electronic Applications

Metal–insulator–metal (MIM) thin-film capacitors having different dielectric layer thicknesses have been fabricated by forming bovine serum albumin (BSA) layers on electrically conductive and optically transparent indium tin oxide (ITO) coated polyethylene terephthalate (PET) substrates by using spin coating technique; the metal contacts at the top surface of BSA films have been deposited via thermal evaporation of gaseous phase aluminum. The capacitance-voltage (CV) measurements reveal the fact that the CV-characteristics of the BSA-based MIM capacitors show variable non-linearity with the change in the thickness of the insulating layer (BSA-layer). The experimentally measured CV-data are fitted with 2nd degree polynomial equations and it has been found that the quadratic voltage coefficient of capacitance (VCC) changes its sign from negative to positive as the thickness of the BSA-layer reduced below 2.0 µm. Finally, successful mechanical flexibility tests, as well as curvature tests have been carried out in order to confirm the possibility of using BSA-based MIM thin-film capacitors in flexible electronic applications in near future.

Measurement Uncertainty in Voltage Coefficients for Compressed-Gas Capacitor Based on a Simplified Tilting Method

High-voltage compressed-gas capacitor is a type of precision equipment commonly used in high voltage laboratories. The voltage dependence of capacitance, in other words, the voltage coefficient of capacitance, is an important factor to ensure the measurement accuracy of capacitors. The simplified tilting method derived from PTB, which provides a solution for measuring the voltage coefficient of the high-voltage capacitor with compressed-gas coaxial cylindrical electrodes structure. However, it is not an easy work for most laboratories. In order to evaluate the voltage coefficient based on the simplified tilting method, a special experimental platform was developed. The high-voltage capacitor installed on the platform can be tilted and rotated at high voltage and be remote-controlled. Base on the developed platform, the voltage coefficient of a 350 kV high-voltage capacitor was measured. In order to verify, it was re-measured by the direct measurement method with a dummy high-voltage capacitor, and before that, the voltage coefficient of the dummy capacitor was calibrated with a near zero-voltage-coefficient capacitor. The results show a good agreement, the consistency of the measurement results is better than 1.2×10^-6 between the two methods. Furthermore, the evaluation of measurement uncertainty in the voltage coefficient determination of capacitor based on simplified tilting method is introduced in detail. The evaluation results show that the expanded uncertainty is significantly better than 2.0×10^-6, k=2.

The Electrical Performances and Leakage Current Conduction Mechanism of Al2O3/ZrO2/SiO2/ZrO2/Al2O3 MIM Capacitors

In this paper, we prepared the Al2O3/ZrO2/SiO2/ZrO2/Al2O3 (AZSZA) metal-insulator-metal (MIM) capacitors by atomic-layer-deposition technique. By increasing the thickness of SiO2 from 0 nm to 3 nm, the quadratic capacitance voltage coefficients improved significantly from 2130 ppm/V2 to −121 ppm/V2 because of the offsetting effects of ZrO2 and SiO2 dielectric. Meanwhile, for our interested SiO2=3nm sample, the capacitance density is 7.40 fF/µm2 and the leakage current density is 3.08 × 10−8 A/cm2 at 5 V. We also studied the leakage current conduction mechanism of AZSZA dielectric MIM capacitors and found that at high field the conduction mechanism was dominated by Poole Frenkel emission.

High-Performance MIM Capacitors for a Secondary Power Supply Application.

Microstructure is important to the development of energy devices with high performance. In this work, a three-dimensional Si-based metal-insulator-metal (MIM) capacitor has been reported, which is fabricated by microelectromechanical systems (MEMS) technology. Area enlargement is achieved by forming deep trenches in a silicon substrate using the deep reactive ion etching method. The results indicate that an area of 2.45 × 103 mm2 can be realized in the deep trench structure with a high aspect ratio of 30:1. Subsequently, a dielectric Al2O3 layer and electrode W/TiN layers are deposited by atomic layer deposition. The obtained capacitor has superior performance, such as a high breakdown voltage (34.1 V), a moderate energy density (≥1.23 mJ/cm2) per unit planar area, a high breakdown electric field (6.1 ± 0.1 MV/cm), a low leakage current (10−7 A/cm2 at 22.5 V), and a low quadratic voltage coefficient of capacitance (VCC) (≤63.1 ppm/V2). In addition, the device’s performance has been theoretically examined. The results show that the high energy supply and small leakage current can be attributed to the Poole–Frenkel emission in the high-field region and the trap-assisted tunneling in the low-field region. The reported capacitor has potential application as a secondary power supply.

Negative VCC in MIM capacitors: modeling and experiments

After the advent of Cu and TiN metallization in high-speed and high-density radio frequency and analog/mixed-signal integrated circuits, new challenges have emerged in achieving low voltage coefficient of capacitance (VCC) in metal-insulation-metal capacitor (MIM) technology. While single layer high-k dielectric MIM capacitors fail to provide low VCC ( $$<100$$ ppm/V $$^{2}$$ ), stacked high-k/ $$\hbox {SiO}_{2}$$ dielectrics show a promising solution as the negative VCC of $$\hbox {SiO}_{2}$$ cancels the positive VCC of high-k materials. To understand the mechanism and origin of negative VCC, a unified analytical model of negative VCC with experimental validation is presented in this paper. This model would be a very useful tool to design high performance MIM capacitors with ultra-low VCC for radio frequency and analog/mixed-signal integrated circuits.

Study of electrical properties of hafnium oxide thin film based metal–insulator–metal capacitors: pre and post metallic annealing

Metal–insulator–metal (MIM) capacitors having hafnium oxide (HfO2) high-κ dielectric thin film were fabricated and subsequently studied for their electrical and micro-structural properties. The MIM capacitors were found to possess low leakage current density of about 2.7 × 10−9 A/cm2 at −1 V, high capacitance density of about 18.1 fF/μm2 at 0 V, 1 MHz and improved quadratic voltage coefficient of capacitance (VCC) of about 120 ppm/V2 at 1 MHz. The electrical properties of MIM capacitors are found to be governed by Frenkel–Poole mechanism at low and intermediate fields ( 1500 kV/cm). The dielectric thin films have amorphous structure which has been correlated with the electrical properties of MIM capacitors. The HfO2 thin film possess good micro-structural properties in term of low roughness, which is in agreement with the obtained electrical properties of thin film based MIM capacitors. Further, post metallic annealing of MIM capacitors results in decrease in leakage current density to ~5.1 × 10−10 A/cm2 at −1 V, increase in capacitance density to ~23.1 fF/μm2 at 0 V, 1 MHz and improvement in quadratic VCC to reach a value of ~95 ppm/V2 at 1 MHz. The electrical characteristics of as-fabricated and annealed MIM capacitors are in accordance with the International Technology Roadmap for Semiconductor 2013 guidelines. The obtained electrical properties suggest the possible use of MIM capacitors in analog/mixed-signal applications.

Nanostructured Anodic Multilayer Dielectric Stacked Metal-Insulator-Metal Capacitors.

This paper presents the fabrication of Al2O3/TiO2/Al2O3 metal-insulator-metal (MIM) capacitor using anodization technique. High capacitance density of > 3.5 fF/μm2, low quadratic voltage coefficient of capacitance of < 115 ppm/V2 and a low leakage current density of 4.457 x 10(-11) A/cm2 at 3 V are achieved which are suitable for analog and mixed signal applications. We found that the anodization voltage played a major role in electrical and structural properties of the thin film. This work suggests that the anodization method can offer crystalline multilayer dielectric stack required for high performance MIM capacitor.

Temperature Dependent Electrical and Dielectrics Properties of Metal-Insulator-Metal Capacitors with Alumina-Silicone Nanolaminate Films

ABSTRACTAlumina-silicone hybrid nanolaminate films were synthesized by plasma enhanced chemical vapor deposition (PECVD) process. PECVD allows digital control over nanolaminate construction, and may be performed at low temperature for compatibility with flexible substrates. These materials are being considered as dielectrics for application such as capacitors in thin film transistors and memory devices. Temperature dependent electrical and dielectric properties of the nanolaminate dielectric films in metal-insulator-metal structures are taken in the range of 200- 340 K to better asses their potential applications for different devices. It is observed that the frequency dependent dielectric constant (εr) and ac conductivity (σac) increase with the temperature. Both quadratic (α) and linear (β) voltage coefficient of capacitance (VCC) increases as the temperature increases. The temperature co-efficient of capacitance (TCC) decreases from 894 to 374 ppm/K as the Al2O3 composition increases in the alumina/silicone nanolaminates. Activation energy (Ea) for hopping conduction mechanism varies from 0.011 eV to 0.008 eV as the alumina composition increases from 50 to 83.3%.

MIM Capacitors Based on ${\rm ZrTiO}_{\rm x}/{\rm BaZr}_{\rm y}{\rm Ti}_{\rm 1-y}{\rm O}_{3}$ Featuring Record-Low VCC and Excellent Reliability

Perovskite-based BaZryTi1-yO3 (BZTO) (y=0.6) with partial crystallization has been found to possess a rather high- κ value of 48.6 and positive quadratic voltage coefficient of capacitance (VCC). Through stacking BZTO and ZrTiOx as laminate dielectric, metal-insulator-metal capacitors using VCC canceling effect advance frontiers by exhibiting a record-low VCC of 14 ppm/V2 at the capacitance of 13.4 fF/μm2, low dielectric loss tangent , and low leakage current of 7.5×10-9 A/cm2 at -1 V. With constant voltage stress at 2.5 V for 1000 s, degradation in leakage current is observed. In addition, excellent reliability of 0.89% capacitance change against stress up to a projected of 10 years is also achieved. The aforementioned characteristics not only compare favorably to other high- κ-based dielectrics, most importantly, but also these results meet ITRS requirements set by 2024.

Performance and Reliability of ${\rm Gd}_{2}{\rm O}_{3}$ and Stacked ${\rm Gd}_{2}{\rm O}_{3}\hbox{-}{\rm Eu}_{2}{\rm O}_{3}$ Metal-Insulator-Metal Capacitors

Gd2O3-based metal-insulator-metal capacitors have been characterized with single layer (Gd2O3) and bilayer (Gd2O3/Eu2O3 and Eu2O3/Gd2O3) stacks for analog and DRAM applications. Although single layer Gd2O3 capacitors provide highest capacitance density (15 fF/μm2), they suffer from high leakage current density, poor capacitance density-voltage linearity, and reliability. The stacked dielectrics help to reduce leakage current density (1.2×10-5 A/cm2 and 2.7 × 10-5 A/cm2 for Gd2O3/Eu2O3 and Eu2O3/Gd2O3, respectively, at -1 V), improve quadratic voltage coefficient of capacitance (331 ppm/V2 and 374 ppm/V2 for Gd2O3/Eu2O3 and Eu2O3/Gd2O3, respectively, at 1 MHz), and improve reliability, with a marginal reduction in capacitance density. This is attributed to lower trap heights as determined from Poole-Frenkel conduction mechanism, and lower defect density as determined from electrode polarization model.

Capacitance Analysis of Highly Leaky $\hbox{Al}_{2} \hbox{O}_{3}$ MIM Capacitors Using Time Domain Reflectometry

Characterization of metal-insulator-metal (MIM) capacitors with a scaled dielectric is a challenge using conventional capacitance–voltage ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$C$</tex></formula> – <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V$</tex></formula> ) measurements due to a high leakage current. In this letter, a method to analyze MIM capacitance that is more immune to the leakage current problem has been successfully demonstrated using time domain reflectometry (TDR). The TDR method can be applied to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">$\hbox{Al}_{2}\hbox{O}_{3}$</tex></formula> MIM capacitors with a capacitance density up to <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\sim\!\!\hbox{11.1}\ \hbox{fF}/\mu\hbox{m}^{2}$</tex></formula> , for which an impedance analyzer has failed to measure capacitance at 1 MHz. Differences in the voltage coefficient of capacitance and dielectric constant ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$k$</tex></formula> ) were also investigated.

Effect of Nitrogen Passivation on the Performance of MIM Capacitors With a Crystalline- $\hbox{TiO}_{2}/\hbox{SiO}_{2}$ Stacked Insulator

TiO2/SiO2 stacked dielectric-based metal-insulator-metal capacitors with different thermal and nitrogen plasma treatments (NPTs) were explored in this letter. As the TiO2 dielectric crystallizes from amorphous phase after a thermal treatment, capacitance density increasing from 7.7 to 11.9 fF/m2 was obtained at the price of aggravating leakage current and wider distribution in device characteristics. With NPT to well passivate grain-boundary-related defects in the crystalline TiO2 film, devices still keep a satisfactory capacitance level of 11.2 fF/μm2 while exhibiting suppressed leakage current by a factor of 53, a lower quadratic voltage coefficient of capacitance (VCC-α) of 30 ppm/V2, near frequency dispersion-free capacitance, a better temperature coefficient of capacitance of 82 ppm/°C, and more controllable device uniformity. The mechanism for the improved electrical characteristics was further confirmed by atomic force microscope. These results suggest that NPT paves a new avenue to further advance the performance of crystalline dielectric-based devices.

High-Performance Metal–Insulator–Metal Capacitors Using Europium Oxide as Dielectric

We report the first demonstration of metal-insulator-metal (MIM) capacitors with Eu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> dielectric for analog and DRAM applications. The influence of different anneal conditions on the electrical characteristics of the fabricated MIM capacitors is studied. FG anneal results in high capacitance density (7 fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ), whereas oxygen anneal results in low quadratic voltage coefficient of capacitance (VCC) (194 ppm/V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at 100 kHz), and argon anneal results in low leakage current density (3.2 ×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at -1 V). We correlate these electrical results with the surface chemical states of the films through X-ray photoelectron spectroscopy measurements. In particular, FG anneal and argon anneal result in sub-oxides, which modulate the electrical properties.

Electrical Characterization of Advanced MIM Capacitors With ${\rm ZrO}_{2}$ Insulator for High-Density Packaging and RF Applications

This paper deals with the electrical and wideband frequency characterizations of metal-insulator-metal (MIM) capacitors integrating the medium-k material ZrO2. First, the in situ material electrical properties are characterized in a frequency range from dc up to 5 GHz by using a microstrip waveguide method. The loss tangent and the permittivity are extracted with frequencies up to 5 GHz. We then investigate the evolution with frequency of the electrical parameters, such as capacitance density, quality factor, temperature coefficient of capacitance, voltage coefficient of capacitance, and cut-off frequency for MIM capacitors which incorporate ZrO2 dielectric layers with thickness from 10 to 45 nm.

MIM Capacitors With Crystalline-$\hbox{TiO}_{2}/ \hbox{SiO}_{2}$ Stack Featuring High Capacitance Density and Low Voltage Coefficient

Metal-insulator-metal (MIM) capacitors with crystalline-TiO2/SiO2 stacked dielectric are explored in this letter. The crystalline TiO2 possesses a high permittivity while the SiO2 provides a negative quadratic voltage coefficient of capacitance (VCC-α) to cancel out the positive VCC-α from the crystalline TiO2. These desirable properties render MIM capacitors with high performance in terms of a capacitance density of 11.9 fF/μm2 with a VCC-α of 90 ppm/V2. With additional N2 plasma treatment on the crystalline TiO2, because of the effective passivation of grain-boundary-related defects and, consequently, a lower leakage current by a factor of 50, the VCC-α can be further lowered to 30 ppm/V2 with slight degradation in capacitance density to 11.2 fF/μm2, which well meets the requirement in 2018 set by ITRS.

Modeling the Negative Quadratic VCC of $\hbox{SiO}_{2}$ in MIM Capacitor

The electrical performance of metal-insulator-metal capacitors with thicknesses from 3 to 13 nm was investigated. The magnitude of the negative quadratic voltage coefficient of capacitance (VCC) of was found to be inversely proportional to the square of its thickness. A postdeposition anneal at 400 reduced substantially. An equation based on the orientation polarization of the dipole moments in was derived, which fits the measured normalized capacitance density versus voltage across very well. This suggests that the negative quadratic VCC of is due to the orientation polarization.

High-Performance $\hbox{Ni}/\hbox{Lu}_{2}\hbox{O}_{3}/ \hbox{TaN}$ Metal–Insulator–Metal Capacitors

We fabricate the Ni/Lu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /TaN metal-insulator-metal capacitor with a high capacitance density of 7.5 fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a relatively small quadratic voltage coefficient of capacitance (VCC) of 75 ppm/V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , a low leakage current of 5 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-8</sup> A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at -1 V, and an excellent ten-year reliability with a very low Δ <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> / <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> of 0.51% at 3 V. These small VCC value and good reliability are attributed to a reduction of carrier injection and trapping into the dielectric.

High-Performance Metal–Insulator-Metal Capacitor Using Stacked $\hbox{TiO}_{2}/\hbox{Y}_{2}\hbox{O}_{3}$ as Insulator

Metal-insulator-metal (MIM) capacitors with single TiO2 and a TiO2/Y2O3 stack as an insulator are explored in this letter. It is found that, at the process temperature higher than 400°C, TiO2 MIM capacitors demonstrate a high capacitance density at the price of an unacceptably high leakage current and voltage coefficient of capacitance (VCC). On the other hand, with the process temperature of 500°C, TiO2/Y2O3 MIM capacitors display desirable characteristics in terms of a large capacitance density of 32.2 fF/μm2, a low VCC of 3490 ppm/ V2, small frequency dispersion, and a low leakage current of 4.5 × 10-9 A/cm2 at -1 V. The Y2O3 film not only provides a high dielectric-electrode band offset but also possesses high thermal stability against crystallization; both are important to suppress leakage current. In addition, the Y2O3 film prevents a TiO2 film from crystallization at 500°C due to the increased entropy caused by incorporated Y atoms, and the amorphous TiO2 film offers a high κ value to achieve a large capacitance density without sacrificing leakage current and VCC.

High-performance metal-insulator-metal capacitor with Ge-stabilized tetragonal ZrO2/amorphous La-doped ZrO2 dielectric

A Ge-stabilized tetragonal ZrO2 dielectric with a permittivity (κ) value of 36.5 has been obtained by annealing a ZrO2/Ge/ZrO2 laminate at 500 °C and it is a more reliable approach toward stabilizing a tetragonal ZrO2 film. However, metal-insulator-metal (MIM) capacitors with the sole tetragonal ZrO2 film as an insulator achieve a high capacitance density of 27.8 fF/μm2 at the price of a degraded quadratic voltage coefficient of capacitance (VCC) of 81 129 ppm/V2 and unacceptably high leakage current. By capping an amorphous La-doped ZrO2 layer with a κ value of 26.3 to block grain boundaries-induced leakage paths of the crystalline ZrO2 dielectric, high-performance MIM capacitors in terms of a capacitance density of 19.8 fF/μm2, a VCC of 3135 ppm/V2, leakage current of 6.5×10−8 A/cm2 at −1 V, as well as a satisfactory capacitance change of 1.21% after ten-year operation can be realized.

Enhanced Voltage Linearity of HfO2 Metal-Insulator-Metal Capacitors by H2O Prepulsing Treatment on Bottom Electrode

The effects of H2O prepulsing treatments on the bottom Pt electrode of metal-insulator-metal (MIM) capacitors prior to HfO2 atomic layer deposition (ALD) were investigated for the first time. We demonstrated a MIM capacitor with capacitance density of 9 fF/μm2, quadratic voltage coefficient of capacitance (VCC) α of 499 ppm/V2 and low leakage current density of 5×10-8 A/cm2 at 1V. X-ray photoelectron spectroscopy (XPS) results reveal that the surfaces of the bottom Pt electrode were partially hydroxylated, which is considered as able to reduce the oxygen vacancies.