MIM capacitors using atomic-layer-deposited high-/spl kappa/ (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ dielectrics

Metal-insulator-metal (MIM) capacitors with (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ high-/spl kappa/ dielectric films were investigated for the first time. The results show that both the capacitance density and voltage/temperature coefficients of capacitance (VCC/TCC) values decrease with increasing Al/sub 2/O/sub 3/ mole fraction. It was demonstrated that the (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitor with an Al/sub 2/O/sub 3/ mole fraction of 0.14 is optimized. It provides a high capacitance density (3.5 fF//spl mu/m/sup 2/) and low VCC values (/spl sim/140 ppm/V/sup 2/) at the same time. In addition, small frequency dependence, low loss tangent, and low leakage current are obtained. Also, no electrical degradation was observed for (HfO/sub 2/)/sub 1-x/(Al/sub 2/O/sub 3/)/sub x/ MIM capacitors after N/sub 2/ annealing at 400/spl deg/C. These results show that the (HfO/sub 2/)/sub 0.86/(Al/sub 2/O/sub 3/)/sub 0.14/ MIM capacitor is very suitable for capacitor applications within the thermal budget of the back end of line process.     

A high-density MIM capacitor (13 fF//spl mu/m/sup 2/) using ALD HfO/sub 2/ dielectrics

Metal-insulator-metal (MIM) capacitors with different HfO/sub 2/ thickness have been investigated. The results show that both the capacitance density and voltage coefficients of capacitance (VCCs) increase with decreasing HfO/sub 2/ thickness. In addition, it is found that the VCCs decrease logarithmically with increasing thickness. Furthermore, the MIM capacitor with 10-nm HfO/sub 2/ shows a record high capacitance density of 13 fF//spl mu/m/sup 2/ 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 /spl times/ 10/sup -8/A/cm/sup 2/ 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.     

Improvement of voltage linearity in high-/spl kappa/ MIM capacitors using HfO/sub 2/-SiO/sub 2/ 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 2/ dielectrics. A MIM capacitor with capacitance density of 6 fF/spl mu/m/sup 2/ and quadratic VCC of only 14 ppm/V/sup 2/ 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 2/ up to 4 V at 125 /spl deg/C.     

High-performance MIM capacitor using ALD high-k HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectrics

For the first time, we successfully fabricated and demonstrated high performance metal-insulator-metal (MIM) capacitors with HfO/sub 2/-Al/sub 2/O/sub 3/ laminate dielectric using atomic layer deposition (ALD) technique. Our data indicates that the laminate MIM capacitor can provide high capacitance density of 12.8 fF//spl mu/m/sup 2/ from 10 kHz up to 20 GHz, very low leakage current of 3.2 /spl times/ 10/sup -8/ A/cm/sup 2/ at 3.3 V, small linear voltage coefficient of capacitance of 240 ppm/V together with quadratic one of 1830 ppm/V/sup 2/, temperature coefficient of capacitance of 182 ppm//spl deg/C, and high breakdown field of /spl sim/6 MV/cm as well as promising reliability. As a result, the HfO/sub 2/-Al/sub 2/O/sub 3/ laminate is a very promising candidate for next generation MIM capacitor for radio frequency and mixed signal integrated circuit applications.     

Metal-insulator-metal RF bypass capacitor using niobium oxide (Nb/sub 2/O/sub 5/) with HfO/sub 2//Al/sub 2/O/sub 3/ barriers

A high capacitance density (C/sub density/) metal-insulator-metal (MIM) capacitor with niobium pentoxide (Nb/sub 2/O/sub 5/) whose k value is higher than 40, is developed for integrated RF bypass or decoupling capacitor application. Nb/sub 2/O/sub 5/ MIM with HfO/sub 2//Al/sub 2/O/sub 3/ barriers delivers a high C/sub density/ of >17 fF//spl mu/m/sup 2/ with excellent RF properties, while maintaining comparable leakage current and reliability properties with other high-k dielectrics. The capacitance from the dielectric is shown to be stable up to 20 GHz, and resonant frequency of 4.2 GHz and Q of 50 (at 1 GHz) is demonstrated when the capacitor is integrated using Cu-BEOL process.     

A high performance MIM capacitor using HfO2 dielectrics

Metal-insulator-metal (MIM) capacitors with a 56 nm thick HfO₂ high-κ dielectric film have been fabricated and demonstrated for the first of time with a low thermal budget (~200°C). Voltage linearity, temperature coefficients of capacitance, and electrical properties are all characterized. The results show that the HfO₂ MIM capacitor can provide a higher capacitance density than Si₃N₄ MIM capacitor while still maintaining comparable voltage and temperature coefficients of capacitance. In addition, a low leakage current of 2×10^-9 A/cm² at 3 V is achieved. All of these make the HfO ₂ MIM capacitor to be very suitable for use in silicon RF and mixed signal IC applications     

Very high density RF MIM capacitors (17 fF//spl mu/m/sup 2/) using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectrics

Using high-/spl kappa/ Al/sub 2/O/sub 3/ doped Ta/sub 2/O/sub 5/ dielectric, we have obtained record high MIM capacitance density of 17 fF//spl mu/m/sup 2/ at 100 kHz, small 5% capacitance reduction to RF frequency range, and low leakage current density of 8.9/spl times/10/sup -7/ A/cm/sup 2/. In combination of both high capacitor density and low leakage current density, a very low leakage current of 5.2/spl times/10/sup -12/ A is calculated for a typical large 10 pF capacitor used in RF IC that is even smaller than that of a deep sub-/spl mu/m MOSFET. This very high capacitance density with good MIM capacitor characteristics can significantly reduce the chip size of RF ICs.     

PVD HfO/sub 2/ for high-precision MIM capacitor applications

Metal-insulator-metal (MIM) capacitors are fabricated using sputtered HfO/sub 2/ with Ta and TaN for top and bottom electrodes, respectively. High-capacitance densities from 4.7 to 8.1 fF//spl mu/m/sup 2/ have been achieved while maintaining the leakage current densities around 1 /spl times/ 10/sup -8/ A/cm/sup 2/ within the normal circuit bias conditions. A guideline for the insulator thickness and its dielectric constant has been obtained by analyzing the tradeoff between the linearity coefficient and the capacitance density.     

RF, DC, and reliability characteristics of ALD HfO/sub 2/-Al/sub 2/O/sub 3/ laminate MIM capacitors for Si RF IC applications

High-performance metal-insulator-metal capacitors using atomic layer-deposited HfO/sub 2/-Al/sub 2/O/sub 3/ laminate are fabricated and characterized for RF and mixed-signal applications. The laminate capacitor can offer high capacitance density (12.8 fF//spl mu/m/sup 2/) up to 20 GHz, low leakage current of 4.9/spl times/10/sup -8/ A/cm/sup 2/ at 2 V and 125/spl deg/C, and small linear voltage coefficient of capacitance of 211 ppm/V at 1 MHz, which can easily satisfy RF capacitor requirements for year 2007 according to the International Technology Roadmap for Semiconductors. In addition, effects of constant voltage stress and temperature on leakage current and voltage linearity are comprehensively investigated, and dependences of quadratic voltage coefficient of capacitance (/spl alpha/) on frequency and thickness are also demonstrated. Meanwhile, the underlying mechanisms are also discussed.     

Performance Improvement of $hbox{Sm}_{2}hbox{O}_{3}$ MIM Capacitors by Using Plasma Treatment After Dielectric Formation

In this letter, we investigate the dependence of the performance of metal-insulator-metal (MIM) capacitors with Sm₂O₃ dielectric on plasma treatment (PT) performed before Sm₂O₃ deposition, after Sm₂O₃ deposition, or both before and after Sm₂O₃ deposition. By performing PT in N₂ ambient (PTN) after Sm₂O₃ dielectric formation, the effective quadratic voltage coefficient of capacitance (VCC) can be reduced from 498 to 234 ppm/V² and the effective linear VCC can be reduced from 742.3 to 172 ppm/V for MIM capacitor with Sm₂O₃ dielectric having a capacitance density of ~ 7.5 fF/mum². The leakage current density at +3.3 V can be reduced from 3.44 10^-7 to 1.60 times 10^-8 A/cm² by performing PTN in both before and after Sm₂O₃ deposition. PTN after dielectric formation is an effective way to improve the performance of high-kappa dielectric MIM capacitors for RF and analog/mixed signal IC applications.     

High-density MIM capacitors using Al2O3 andAlTiOx dielectrics

We have investigated the electrical characteristics of Al₂ O₃ and AlTiO_x MIM capacitors from the IF (100 KHz) to RF (20 GHz) frequency range. Record high capacitance density of 0.5 and 1.0 μF/cm² are obtained for Al₂ O₃ and AlTiO_x MIM capacitors, respectively, and the fabrication process is compatible to existing VLSI backend integration. However, the AlTiO_x MIM capacitor has very large capacitance reduction at increasing frequencies. In contrast, good device integrity has been obtained for the Al₂O₃ MIM capacitor as evidenced from the small frequency dependence, low leakage current, good reliability, small temperature coefficient, and low loss tangent     

Analysis of reliability characteristics of high capacitance density MIM capacitors with SiO2-HfO2-SiO2 dielectrics

In this paper, reliability as well as electrical properties of high capacitance density metal-insulator-metal (MIM) capacitor with hafnium-based dielectric is analyzed in depth. The fabricated MIM capacitor exhibits not only high capacitance density but also low voltage coefficient of capacitance (VCC) and low temperature coefficient of capacitance (TCC). It also has a low leakage current level of about ∼1 nA/cm² at room temperature and 1 V. However, it is shown that voltage linearity has a different dependence on the polarity of applied bias as temperature increases maybe due to the bulk traps between the metal electrode and high-k dielectric interface. In addition, the effect of charge trapping and de-trapping on the voltage linearity is analyzed under constant voltage stress.     

Evidence and understanding of ALD HfO/sub 2/-Al/sub 2/O/sub 3/ 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.     

Effective Modulation of Quadratic Voltage Coefficient of Capacitance in MIM Capacitors Using $hbox{Sm}_{2}hbox{O}_{3}/hbox{SiO}_{2}$ Dielectric Stack

We report the first demonstration of metal–insulator–metal (MIM) capacitors with $hbox{Sm}_{2}hbox{O}_{3}/hbox{SiO}_{2}$ stacked dielectrics for precision analog circuit applications. By using the “canceling effect” of the positive quadratic voltage coefficient of capacitance (VCC) of $hbox{Sm}_{2}hbox{O}_{3}$ and the negative quadratic VCC of $hbox{SiO}_{2}$, MIM capacitors with capacitance density exceeding 7.3 $hbox{fF}/muhbox{m}^{2}$ , quadratic VCC of around $-hbox{50} hbox{ppm/V}^{2}$ , and leakage current density of $hbox{1} times hbox{10}^{-7} hbox{A/cm}^{2}$ at $+$3.3 V are successfully demonstrated. The obtained capacitance density and quadratic VCC satisfy the technical requirements specified in the International Technology Roadmap for Semiconductors through the year 2013 for MIM capacitors to be used in precision analog circuit applications.      

HfO/sub 2/ MIS capacitor with copper gate electrode

Metal-insulator-semiconductor capacitors were fabricated using atomic vapor deposition HfO/sub 2/ dielectric with sputtered copper (Cu) and aluminum (Al) gate electrodes. The counterparts with SiO/sub 2/ dielectric were also fabricated for comparison. Bias-temperature stress and charge-to-breakdown (Q/sub BD/) test were conducted to examine the stability and reliability of these capacitors. In contrast with the high Cu drift rate in an SiO/sub 2/ dielectric, Cu in contact with HfO/sub 2/ seems to be very stable. The HfO/sub 2/ capacitors with a Cu-gate also depict higher capacitance without showing any reliability degradation, compared to the Al-gate counterparts. These results indicate that HfO/sub 2/ with its considerably high density of 9.68 g/cm/sup 3/ is acting as a good barrier to Cu diffusion, and it thus appears feasible to integrate Cu metal with the post-gate-dielectric ultralarge-scale integration manufacturing processes.     

Very high-density (23 fF//spl mu/m/sup 2/) RF MIM capacitors using high-/spl kappa/ TaTiO as the dielectric

A very high density of 23 fF//spl mu/m/sup 2/ has been measured in RF metal-insulator-metal (MIM) capacitors which use high-/spl kappa/ TaTiO as the dielectric. In addition, the devices show a small reduction of 1.8% in the capacitance, from 100 kHz to 10 GHz. Together with these characteristics the MIM capacitors show low leakage currents and a small voltage-dependence of capacitance at 1 GHz. These TaTiO MIM capacitors should be useful for precision RF circuits.     

Integrated high-/spl kappa/ (/spl kappa/ /spl sim/19) MIM capacitor with Cu/low-/spl kappa/ interconnects for RF application

We demonstrate a high-performance metal-high /spl kappa/ insulator-metal (MIM) capacitor integrated with a Cu/low-/spl kappa/ backend interconnection. The high-/spl kappa/ used was laminated HfO/sub 2/-Al/sub 2/O/sub 3/ with effective /spl kappa/ /spl sim/19 and the low-/spl kappa/ dielectric used was Black Diamond with /spl kappa/ /spl sim/2.9. The MIM capacitor (/spl sim/13.4 fF//spl mu/m/sup 2/) achieved a Q-factor /spl sim/53 at 2.5 GHz and 11.7 pF. The resonant frequency f/sub r/ was 21% higher in comparison to an equivalently integrated Si/sub 3/N/sub 4/-MIM capacitor (/spl sim/0.93 fF//spl mu/m/sup 2/) having similar capacitance 11.2 pF. The impacts of high-/spl kappa/ insulator and low-/spl kappa/ interconnect dielectric on the mechanism for resonant frequency improvement are distinguished using equivalent circuit analysis. This letter suggests that integrated high-/spl kappa/ MIM could be a promising alternative capacitor structure for future high-performance RF applications.     

Improvement of the Performance of TiHfO MIM Capacitors by Using a Dual Plasma Treatment of the Lower Electrode

We show that a conventional nitrogen plasma treatment is insufficient to suppress the formation of an interfacial layer at the bottom electrode of TiHfO metal-insulator-metal (MIM) capacitors. However, the capacitance density and leakage current of TaN/TiHfO/TaN MIM capacitors monotonically improve by exposing the lower TaN electrode to an additional oxygen plasma treatment. By performing dual oxygen and nitrogen plasma treatments on the lower electrode, the leakage current was 4.8 times 10^-6 A/cm² (at -1 V) at a 28 fF/ mum² capacitance density.     

High-Performance Metal–Insulator–Metal Capacitors Using Amorphous BaSm2Ti4O12 Thin Film

The dielectric properties of the amorphous BaSm₂Ti₄O₁₂ (BSmT) film with various thicknesses were investigated to evaluate its potential use as a metal-insulator-metal (MIM) capacitor. An amorphous 35-nm-thick BSmT film grown at 300 degC exhibited a high capacitance density of 9.9 fF/mum² at 100 kHz and a low leakage current density of 1.790 nA/cm² at 1 V. The quadratic and linear voltage coefficients of capacitance of the film were 599 ppm/V² and -81 ppm/V at 100 kHz, respectively. The temperature coefficient of capacitance of the film was also low about 236 ppm/degC at 100 kHz. These results confirmed the suitability of the amorphous BSmT film as a high-performance MIM capacitor     

RFIC TaN/SrTiO$_3/$TaN MIM Capacitors With 35fF$/muhboxm^2$Capacitance Density

A very high density of 35$hboxfF/muhboxm^2$is measured in a radio frequency (RF) metal-insulator-metal (MIM) capacitor using high-$kappa (kappa=hbox169)$$hboxSrTiO_3$fabricated by very large scale integration (VLSI) back-end integration. A very small capacitance reduction of 4.1% from 100kHz to 10GHz, low leakage current of 1$times hbox10^-7 hboxA/cm^2$at 1V are simultaneously measured. The small voltage dependence of a capacitance$Delta C/C$of 637ppm is also obtained at 2GHz, which ensures this MIM capacitor useful for high precision circuits operated at a RF regime.