Voltage Coefficient Of Capacitance Research Articles

Atomic Layer Deposited High‐κ Films and Their Role in Metal‐Insulator‐Metal Capacitors for Si RF/Analog Integrated Circuit Applications

AbstractIn this paper, we present an extensive evaluation of metal‐insulator‐metal (MIM) capacitors by comparing various high‐κ dielectric structures based on atomic layer deposited HfO2 and Al2O3 films at two thicknesses. The results indicate that laminate‐structured MIM capacitors provide superior performance to their sandwiched/stacked counterparts in both thin (∼13 nm) and thick (∼55 nm) dielectric films. Benefits include low leakage current, good polarity‐independent electrical characteristics, high‐breakdown electrical field (voltage), and long time‐to‐breakdown while maintaining comparable capacitance density and voltage coefficients of capacitance. It is noted, however, that the benefits of the laminate structure become less significant when the dielectric thickness decreases. The advantages of the laminate structure are mainly attributed to the alternate insertions of Al2O3 into bulk HfO2, thereby preventing crystallization of HfO2.

Evidence and Understanding of ALD<tex>$hbox HfO_2hbox --hbox Al_2hbox O_3$</tex>Laminate MIM Capacitors Outperforming Sandwich Counterparts

Metal-insulator-metal capacitors with atomic-layer-deposited HfO/sub 2/-Al/sub 2/O/sub 3/ laminated and sandwiched dielectrics have been compared, for the first time, for analog circuit applications. The experimental results indicate that significant improvements can be obtained using the laminated dielectrics, including an extremely low leakage current of 1/spl times/10/sup -9/ A/cm/sup 2/ at 3.3V and 125/spl deg/C, a high breakdown electric field of /spl sim/3.3MV/cm at 125/spl deg/C, good polarity-independent electrical characteristics, while retaining relatively high capacitance density of 3.13 fF//spl mu/m/sup 2/ as well as voltage coefficients of capacitance as low as -80 ppm/V and 100 ppm/V/sup 2/ at 100 kHz. The underlying mechanism is likely due to alternate insertions of Al/sub 2/O/sub 3/ layers that reduce the thickness of each HfO/sub 2/ layer, hereby efficiently inhibiting HfO/sub 2/ crystallization, and blocking extensions of grain boundary channels from top to bottom as well as to achieve good interfacial quality.

Improvement of Voltage Linearity in High-<tex>$kappa$</tex>MIM Capacitors Using<tex>$hbox HfO_2hbox --hbox SiO_2$</tex>Stacked Dielectric

It is demonstrated that the voltage coefficients of capacitance (VCC) in high-/spl kappa/ metal-insulator-metal (MIM) capacitors can be actively engineered and voltage linearity can be significantly improved maintaining high capacitance density, by using a stacked insulator structure of high-/spl kappa/ and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dielectrics. A MIM capacitor with capacitance density of 6 fFμm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and quadratic VCC of only 14 ppm/V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been demonstrated together with excellent frequency and temperature dependence (temperature coefficients of capacitance of 54 ppm /spl deg/C) as well as low leakage current of less than 10 nA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> up to 4 V at 125 /spl deg/C.

MIM Capacitors Using ALD Al2O3 for RF IC and DRAM Applications

ABSTRACTMetal-insulator-metal (MIM) capacitors were fabricated in a coplanar waveguide type using the Al2O3 thin film. The Al2O3 film was grown by atomic layer deposition(ALD) using Methyl-Pyrolidine-Tri-Methyl-Aluminum (MPTMA) and H2O on Ti. The capacitance per unit area of the fabricated MIM capacitor was 0.229 μF/cm2. And it had lower voltage coefficient of capacitance (VCC) and lower leakage current than that of Al2O3 MIM capacitor prepared by Al oxidation and Si3N4 MIM capacitor prepared by PECVD respectively. The fabricated Al2O3 MIM capacitors prepared by ALD exhibited low VCC, low leakage current, small frequency-dependent capacitance reduction, low temperature coefficient of capacitance (TCC) and good reliability. The characteristics of the device were suitable for RF ICs and DRAM.

Lanthanide (Tb)-doped HfO2 for high-density MIM capacitors

A high-density metal-insulator-metal (MIM) capacitor with a lanthanide-doped HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dielectric prepared by physical vapor deposition (PVD) is presented for the first time. A significant improvement was shown in both the voltage coefficient of capacitance (VCC) and the leakage current density of MIM capacitor, yet the high capacitance density of HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> dielectrics was maintained by achieving the doping of Tb with an optimum concentration in HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . This technique allows utilizing thinner dielectric film in MIM capacitors and achieving a capacitance density as high as 13.3 fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> with leakage current and VCC values that fully meet requirements from year 2005 for radio frequency (RF) bypass capacitors applications.

A high-density MIM capacitor (13 fF/μm/sup 2/) using ALD HfO2 dielectrics

Metal-insulator-metal (MIM) capacitors with different HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thickness have been investigated. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> thickness. In addition, it is found that the VCCs decrease logarithmically with increasing thickness. Furthermore, the MIM capacitor with 10-nm HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> shows a record high capacitance density of 13 fF/μm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> and a VCC of 607 ppm/V, which can meet the requirement of the International Technology Roadmap for Semiconductors. It can also provide a low leakage current of 5.95 × 10/sup -8/A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> at room temperature at 1 V, low tangent values below 0.05, and a small frequency dependence. These results indicate that the devices are suitable for use in silicon integrated circuit applications.

Mim Capacitors with HfO2 and HfAlOx for Si RF and Analog Applications

AbstractThe MIM capacitors with HfO2 and HfAlOx are investigated for Si RF and analog applications. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing the HfO2 thickness. A high capacitance density of 13 fF/μm2with a low leakage current and a VCC of 607 ppm/V is obtained for 10 nm HfO2 MIM capacitor, which can meet the requirement of the ITRS roadmap by 2007 for silicon RF application. On the other hand, it was found that both the capacitance density and voltage coefficients of capacitance (VCC) values of the HfAlOx MIM capacitors decrease with increasing Al2O3 concentration. The results show that HfAlOx MIM capacitor with an Al2O3 mole fraction of 0.14 is optimized. It provides a high capacitance density of 3.5 fF/μm2 and a low VCC of μ140 ppm/V2. Also, small frequency dependence, low leakage current, and low loss tangent are obtained. Thus, the HfAlOx MIM capacitor with an Al2O3 mole ratio of 0.14 is very suitable for use in silicon analog applications.

Effect of the nitrous oxide plasma treatment on the MIM capacitor

We report the demonstration of near zero voltage coefficient of capacitance (VCC) by exposing the silicon nitride dielectric of the metal-insulator-metal capacitor (MIM) to nitrous oxide (N/sub 2/O) plasma. Oxidization in the N/sub 2/O plasma enhanced the hard breakdown field, whereby an excess of 9 MV/cm was achieved. In addition, low-temperature coefficient of capacitance (TCC) of < 20 ppm/K and high dielectric constant /spl ges/ 6.5 were preserved.

A novel cross-coupled inter-poly-oxide capacitor for mixed-mode CMOS processes

The inter-poly-oxide (IPO) capacitor is one of the main elements in present mixed-mode CMOS process technologies. However, the phenomenon of poly depletion causes a significant change in the measured capacitance with applied voltage. This effect, expressed in terms of the voltage coefficient of capacitance (VCC), can seriously deteriorate analog precision. In this letter, a novel cross-coupled scheme is proposed for the IPO capacitors. The resulting VCC has a very low measured value of 2 ppm/V in a 0.35-/spl mu/m standard mixed-mode CMOS process, achieved without any unconventional approaches.

The absolute calibration of voltage transformers

An account is given of equipment and measuring techniques in use at the National Standards Laboratory, Australia, for calibrating voltage transformers. The equipment employs 3-terminal air-dielectric capacitors to form a voltage divider, the ratio and phase defect angle of which are determined by a self-contained build-up technique. Owing to the use of virtually loss-free capacitors, the phase angle of the divider is negligibly small.Two methods are described for calibrating transformers. In one, ratio balance is obtained by means of a small auxiliary variable-ratio voltage transformer, and phase balance by current injection into one of the detector bridge junctions. In the other method, ratio balance is provided by a variable 3-terminal air-capacitor in the low-voltage arm of the divider, and phase balance by voltage injection in series with that arm, a feedback amplifier providing a low-impedance injection circuit. In both methods the accuracy of measurement is approximately 2 parts in 105 in ratio and 0.05′ in phase angle.The air-dielectric capacitors used in the voltage divider are tested to ensure that they have no significant voltage coefficient of capacitance or loss angle.