Polarization-switching D/A converter

This paper describes a novel digital-to-analog (D/A) conversion technique, which uses the analog quantity polarization as a D/A conversion medium. It can be implemented by CMOS capacitors or by ferroelectric capacitors, which exhibit strong nonlinearity in charge versus voltage behavior. Because a ferroelectric material inherently has spontaneous polarization and generally has a large dielectric constant, the effective capacitance of a ferroelectric capacitor is much larger than that of a CMOS capacitor of the same size. This ensures less influence of bottom-electrode parasitic capacitance on a ferroelectric capacitor. Furthermore, a data converter based on ferroelectric capacitors possesses the potential nonvolatile memory function owing to ferroelectric hysteresis. Along with the architecture proposed for polarization-switching digital-to-analog converter (PDAC), its circuit implementation is introduced. Described is implementation of two 9-bit bipolar PDACs: one is based on CMOS capacitors and the other on off-chip ferroelectric capacitors. Experimental results are presented for the performance of these two prototypes.     

PLL jitter reduction by utilizing a ferroelectric capacitor as a VCO timing element

Ferroelectric capacitors have steadily been integrated into semiconductor processes due to their potential as storage elements within memory devices. Polarization reversal within ferroelectric capacitors creates a high nonlinear dielectric constant along with a hysteresis profile. Due to these attributes, a phase-locked loop (PLL), when based on a ferroelectric capacitor, has the advantage of reduced cycle-to-cycle jitter. PLLs based on ferroelectric capacitors represent a new research area for reduction of oscillator jitter.     

Multifiber ceramic capacitor

A new type of capacitor, multifiber capacitor (MFC) is proposed. It is made up of fiber capacitors (elements) connected in parallel and bonded together with a binder. Each element consists of fiber core (inner electrode), dielectric coating and outer electrode. Analysis indicates that MFC has the optimum capacitance in comparison with multilayer capacitor (MLC) when the diameter of fiber core is carefully matched by the thickness of dielectric coating. Since dielectric layer of a wide range of thickness can be produced more easily as fiber coating than as flat tape, MFC can cover a wider range of capacitance than MLC. Apart from as a possible substitute or supplement to MLC, MFC is potentially useful to bridge the gap between ceramic MLC and thin film capacitor used in integrated circuits. MFC also has better resistance to dielectric breakdown. The possible techniques for the preparation of MFC are also described.     

新型多纤维陶瓷电容器的设计

提出了一种新型多纤维陶瓷电容器(MFC)。MFC由众多纤维电容器并联而成，而每根纤维电容器由内电极(导电纤维)、介电层和外电极构成。理论分析表明，当纤维直径与介电层厚度相匹配时，MFC的电容比多层电容器(MLC)的电容大，而且MFC也具有更优异的抗击穿性能。     

Measurement of dielectric absorption of capacitors and analysis ofits effects on VCOs

In the integrators applied in A-to-D converters, smart sensors and other processing circuits, the accuracy is directly limited by the performance of the integrating element: the capacitor. An important nonideality of the capacitors concerns the short-term effects of dielectric absorption. This paper presents an accurate method to measure these short-term effects and discusses the measurement results for standard industrial capacitors, MOS and junction capacitors, parasitic capacitors of assembling materials and coaxial-cable capacitors. The special precautions to be taken to obtain the required accuracy for very short measurement times are also discussed. It is shown that the dielectric absorption of a commonly used polycarbonate capacitor causes a nonlinearity of 0.6% for a VCO in the frequency range from 1 kHz to 100 kHz. A very large dielectric-absorption effect has been found for commonly used epoxy printed-circuit boards, which means that special care has to be taken when this material is applied in accurate VCOs     

Dielectric properties of BaTiO<Subscript>3</Subscript>/epoxy composites by lamination process for embedded capacitor application

Because of the fabricability of polymer and excellent dielectric properties of ceramics, ceramic-polymer composites have been investigated widely for embedded capacitors which can improve electric performance greatly. In order to obtain further application of composite, the embedded capacitors with three-layer sandwich structure containing the BaTiO₃/epoxy composites as dielectric layer and copper foil as electrodes were fabricated. The dielectric properties are improved by preventing the defect in dielectric layer through lamination process. Our results show that the capacitors exhibit high dielectric permittivity (ε = 20), low dielectric loss (0.01) at 10³ Hz from 40 to 100 °C and high breakdown strength (24 kV/mm), which indicate that the lamination is a promising process for embedded capacitor fabrication and BaTiO₃/epoxy composites have potential for high-performance embedded capacitors application in field of microelectronics.     

Study of electrical and micro-structural properties of high-κ gate dielectric stacks deposited using pulse laser deposition for MOS capacitor applications

The electrical properties of hafnium oxide (HfO₂) gate dielectric as a metal–oxide–semiconductor (MOS) capacitor structure deposited using pulse laser deposition (PLD) technique at optimum substrate temperatures in an oxygen ambient gas are investigated. The film thickness and microstructure are examined using ellipsometer and atomic force microscope (AFM), respectively to see the effect of substrate temperatures on the device properties. The electrical J–V, C–V characteristics of the dielectric films are investigated employing Al–HfO₂–Si MOS capacitor structure. The important parameters like leakage current density, flat-band voltage (V_fb) and oxide-charge density (Q_ox) for MOS capacitors are extracted and investigated for optimum substrate temperature. Further, electrical studies of these MOS capacitors have been carried out by incorporating La₂O₃ into HfO₂ to fabricate HfO₂/La₂O₃ dielectric stacks at an optimized substrate temperature of 800 °C using a PLD deposition technique under oxygen ambient. These Al–HfO₂–La₂O₃–Si dielectric stacks MOS capacitor structure are found to possess better electrical properties than that of HfO₂ based MOS capacitors using the PLD deposition technique.     

等效厚度评估GaAs MMIC的Si3N4电容可靠性

通过不同GaAs MMIC的MIMSi3N4电容结构,运用TDDB理论研究分析了斜坡电压下的MIM Si3N4电容的导电特性和击穿特性,确定了GaAs MMIC的MIM Si3N4电容失效不是介质本征击穿导致失效,而主要是由Si3N4介质的缺陷引起。基于缺陷导致介质电场击穿的原理,提出了等效厚度模型评估和监测GaAs MMIC的Si3N4介质电容的质量和可靠性的新方法,可以用于工艺生产线实现对Si3N4介质电容的质量和可靠性进行快速评估和监测。     

New Fused-Silica-Dielectric 10-and 100-pF Capacitors and a System for Their Measurement

New instruments have been designed to bring to standards laboratories the improved accuracy of capacitor calibrations developed by the National Bureau of Standards. The new 10-and 100-pF reference standard capacitors, based upon an NBS design, use a fused-silica dielectric with gold electrodes to provide the time and voltage stability required for calibrations to parts in 107. To maintain the capacitor temperature constant to within 0.01 °C, one model of the capacitors is designed for use in an oil bath, the other model is fitted with a new, stable, thermostatically controlled air bath. The system to measure these capacitors with a precision of parts in 108 consists of a bridge, detector, and oscillator. For these special measurements and for the general calibration of a wide range of capacitors, the new transformer-ratio-arm bridge has 12 capacitance decades and a range of 10 MAF-10-7 pF, and five conductance decades and a range of 103110-10 tmho. The new phasesensitive detector and power oscillator provide high sensitivity to bridge imbalance over the frequency range 10 Hz-100 kHz.     

Peapod‐like Li3VO4/N‐Doped Carbon Nanowires with Pseudocapacitive Properties as Advanced Materials for High‐Energy Lithium‐Ion Capacitors

Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double‐layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li₃VO₄ with low Li‐ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N‐doped carbon‐encapsulated Li₃VO₄ nanowires are synthesized through a morphology‐inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g^?1 at 0.1 A g^?1, excellent rate capability, and long‐term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge‐transfer, the Li₃VO₄/N‐doped carbon nanowires exhibit a high‐rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li₃VO₄/N‐doped carbon nanowires delivers a high energy density of 136.4 Wh kg^?1 at a power density of 532 W kg^?1, revealing the potential for application in high‐performance and long life energy storage devices.     

Dual-Ramp A/D Converter Error Due to Nonideal Integrator Capacitor

It is shown that very high accuracy hybrid packaged dual-ramp analog-to-digital converters can be built using ceramic NPO-type chip capacitors that exhibit a dielectric absorption specification of 0.75 percent. Capacitor recovery voltage is shown versus time for several 0.01-/g-m/F NPO-type ceramic capacitors. An absorptive capacitor model for the NPO capacitor is shown. Typical component values for an absorptive model of an 0.01-/g=m/F NPO capacitor are determined. The worst case integrator error due to dielectric absorption in a particular synchro-to-digital converter utilizing two dual-ramp converters with 0.01-/g=m/F integrator capacitors is shown to be in the order of microvolts.     

Y5U multilayer ceramic capacitors with high-specific capacitance and low-equivalent series resistance

A dielectric powder material, for Y5U multilayer ceramic capacitors was developed in the Pb(Mg(1/3)Nb(2/3))O (3)-Pb(Ni(1/3)Nb(2/3))O(3)-PbTiO (3) ternary system by using an alkoxide process. Multilayer ceramic chip capacitors (10 muF) with high specific capacitances were fabricated using this powder. A Ag80%-Pd20% alloy was used for the internal electrodes. The alkoxide-derived capacitor had an extremely high specific capacitance of about 500 muF/cm(3) and a small temperature dependence meeting Y5U specifications of the EIA standard. The equivalent series resistance was approximately 20 mOmega at 500 kHz. The breakdown voltages of the capacitor were 300 V or higher. In accelerated load life tests and load humidity tests, no degradation of insulation resistance was found during 1000 h of testing.     

Development and characterization of a high dielectric constant paste based on BaTiO3 for use in thick-film capacitors

Results of measurements on a thick-film capacitor based on a paste of mixed ferroelectric phases made out of crystallization from a glassy phase are presented. This material can be used as a high dielectric constant paste for designing capacitors in hybrid circuits. The tanδ is observed to decrease with rise in temperature.     

Di-block copolymer surfactant study to optimize filler dispersion in high dielectric constant polymer-ceramic composite

Embedded capacitor technology can improve electrical performance and reduce assembly cost compared with traditional discrete capacitor technology. Polymer-ceramic composites have been of great interest as embedded capacitor material because they combine the processability of polymers with the desired electrical properties of ceramics. Dispersion of ceramic particles is a critical factor to affect the effective dielectric constant of polymer-ceramic composite. Di-block copolymer surfactants have been used to prevent agglomeration of the ceramic particles. It was found that di-block copolymer surfactant could improve the ceramic dispersion better than monomer surfactant. Using di-block copolymer surfactant, higher dielectric constant was achieved at lower ceramic loading level. This high dielectric constant polymer-ceramic composite material has much better mechanical properties and can be used for the integral capacitors in the SOP (system on a package) substrate.     

高性能BaTiO_3/PVDF介电复合材料及其薄膜电容器应用

选用柔性高分子材料聚偏氟乙烯（PVDF）作为基体,纳米钛酸钡陶瓷（BaTiO3）作为填充相,采用简单的溶液共混以及流延工艺制备BaTiO3/PVDF薄膜。通过SEM观察了复合材料体系的微观结构,研究了BaTiO3/PVDF介电复合材料的介电性能。把所制备的BaTiO3/PVDF复合材料薄膜（70mm×30mm×25μm...     

Mechanical vs. electrical failure mechanisms in high voltage,high energy density multilayer ceramic capacitors

Causes of breakdown, both mechanical and electrical, in high voltage, high energy density, BaTiO₃ capacitors were studied. The flexural strength of the capacitors was 96 MPa. Failure was due to surface defects or pores close to the surfaces of the samples. The dielectric breakdown strength of the samples was 181 kV/cm. The causes of breakdown were either electrode end effects or pores between the dielectric and electrode layers. Weibull statistics were used to determine if there was a correlation between mechanical failure and dielectric breakdown. A strong correlation between the two types of failure was not found in the study, in contrast to earlier studies of single dielectric layer capacitor materials.     

Carboxylated Poly (p-Phenylene Terephthalamide) Reinforced Polyetherimide for High-Temperature Dielectric Energy Storage

Dielectric energy storage polymers play a vital role in advanced electronics and electrical systems, due to their high breakdown strength, excellent reliability, and easy fabrication. However, the low dielectric constant and poor thermal resistance of dielectric polymers limit their energy storage density and working temperatures, making them less versatile for broader applications. In this work, a novel carboxylated poly (p-phenylene terephthalamide) (c-PPTA) is synthesized and employed to simultaneously enhance the dielectric constant and thermal resistance of polyetherimide (PEI), leading to a discharged energy density of 6.4 J cm⁻³ at 150 °C. The introduction of c-PPTA molecules effectively reduces the Π Π stacking effect and increases the average chain spacing between polymer molecules, which is conducive to improving the dielectric constant. Additionally, c-PPTA molecules with stronger positive charges and high dipole moments can capture electrons, resulting in reduced conduction loss and enhanced breakdown strength at high temperatures. The coiled capacitor fabricated with the PEI/c-PPTA film exhibits superior capacitance performances and higher working temperatures compared to commercial metalized PP capacitors, demonstrating great potential for dielectric polymers in high-temperature electronic and electrical energy storage systems.     

Evaporated insulating layers for thin film circuits

The basic properties of a new glass-forming dielectric material were studied with regard to its application in thin film circuits. Direct evaporation by electron bombardment leads to highly insulating layers with good reproducibility. Thin film capacitors are deposited in a high vacuum onto glass substrates or glazed ceramics through metal masks.

The dielectric constant of =3.7 and the high breakdown field of about 4–7 MV cm⁻¹ are important for conductor cross-overs. This material is also of interest as a highly stable capacitor dielectric because of its low loss (tan δ=0.2%) and a temperature coefficient of about +25 ppm K⁻¹.     

Lead zirconate titanate thin film capacitors on electroless nickel coated copper foils for embedded passive applications

Lead zirconate titanate (PZT, 52/48) thin film capacitors were prepared on electroless Ni coated Cu foil by chemical solution deposition for printed wiring board embedded capacitor applications. Phase development, dielectric properties, and leakage characteristics of capacitors were investigated, in particular as a function of the process temperature. Dielectric properties of the capacitors were dependent on the crystallization temperature, and capacitance densities of more than 350 nF/cm² and loss tangent of less than 0.03 were measured for capacitors crystallized below 600 °C. Lowest leakage current densities (around 2 × 10^− 7 A/cm² at 10 V direct current (DC)) and highest breakdown fields could be obtained for capacitors crystallized at 650 °C.Capacitors with different thickness and a two-layer capacitor model were used in analyzing the interface layer between PZT and the underlying electroless Ni. From the capacitance and leakage measurements, it is suggested that the interface reaction layer has low permittivity (K around 30) and high defect concentration, which has an important effect on the electrical properties of capacitors. This interface is from the reaction of the electroless nickel layer with the adjacent PZT, and may specifically be moderated by the nickel phosphide (Ni-P) phase, transformed from amorphous Ni during the annealing step.The results have significant implications for embedded capacitors in printed wiring boards. They demonstrate that the process can be tuned to produce either voltage independent capacitors with low leakage and high breakdown fields (above 30 V DC), or the more usual hysteretic, switching, ferroelectric capacitors with higher capacitance densities.     

Elimination of the anomalous humidity effect in precisioncapacitance based transducers

An anomalous humidity effect has been observed in a precision capacitor-based displacement transducer. This effect displays a threshold, well below the dew point, above which the capacitance change exceeds by far the increase in moisture-caused dielectric constant of the air dielectric. This effect, common to air capacitors in general, results from water vapor adsorption on insulator surfaces. It can be eliminated by shielding the capacitor in a way which removes the humidity sensitive flux from the internal electric field of the capacitor