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(a) Schematic of a 3-D trench capacitor; (b) Cross-sectional SEM image of the 3-D capacitors with the FE (1 nm)/AFE (9 nm) stack, which are fabricated on the silicon trench substrate with an aspect ratio of 7:1; (c) Dependence of the P-E hysteresis loops on external electric field for the 3-D trench capacitor with the FE (1 nm)/AFE (9 nm) stack; (d) P-E hysteresis loops for a planar and a 3D FE (1 nm)/AFE (9 nm) stackbased capacitor; (e) the extracted ESD and ESE as a function of electric field for the 3-D capacitor; (f) Weibull distributions of the extracted maximum ESD and ESE for the 3-D and planar capacitors (30 devices are measured for each kind of capacitor).
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Thanks to their excellent compatibility with the complementary metal-oxide-semiconductor (CMOS) process, antiferroelectric (AFE) HfO2/ZrO2-based thin films have emerged as potential candidates for high-performance on-chip energy storage capacitors of miniaturized energy-autonomous systems. However, increasing the energy storage density (ESD) of cap...
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... is well known that a much higher ESD per footprint unit can be realized through integration of the capacitor into a 3-D template because of a significant increase in the surface area of electrodes. Therefore, it is of significance to integrate the FE (1 nm)/AFE (9 nm) capacitor into deep silicon trenches. Fig. 8(a) shows the schematic of the fabricated 3-D capacitor, and the corresponding cross-sectional SEM image is demonstrated in Fig. 8(b). The regular trenches with vertical and smooth side walls are obtained successfully, showing an aspect ratio of 7:1. Moreover, diverse material layers including TiN electrodes and HfxZr1-xO2 dielectrics are ...
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... of the capacitor into a 3-D template because of a significant increase in the surface area of electrodes. Therefore, it is of significance to integrate the FE (1 nm)/AFE (9 nm) capacitor into deep silicon trenches. Fig. 8(a) shows the schematic of the fabricated 3-D capacitor, and the corresponding cross-sectional SEM image is demonstrated in Fig. 8(b). The regular trenches with vertical and smooth side walls are obtained successfully, showing an aspect ratio of 7:1. Moreover, diverse material layers including TiN electrodes and HfxZr1-xO2 dielectrics are well filled into the trenches by PEALD (see the inset). The dependence of the P-E hysteresis loops on external electric field for ...
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... obtained successfully, showing an aspect ratio of 7:1. Moreover, diverse material layers including TiN electrodes and HfxZr1-xO2 dielectrics are well filled into the trenches by PEALD (see the inset). The dependence of the P-E hysteresis loops on external electric field for the 3-D trench capacitor with the FE (1 nm)/AFE (9 nm) stack are shown in Fig. 8(c), as the maximum electric field increases from 1 to 5.7 MV/cm, the resulting P-E loops gradually widen, and the max polarization per footprint unit increases from 13.3 to 163.2 μC/cm 2 . The green area indicates the recoverable ESD (Wrec), which can be calculated by the integration of electric field by polarization per footprint unit. ...
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... as the maximum electric field increases from 1 to 5.7 MV/cm, the resulting P-E loops gradually widen, and the max polarization per footprint unit increases from 13.3 to 163.2 μC/cm 2 . The green area indicates the recoverable ESD (Wrec), which can be calculated by the integration of electric field by polarization per footprint unit. As shown in Fig. 8(d), compared with the planar capacitor, the polarization per footprint unit for the 3-D trench capacitor greatly increases, which is attributed to a significant increase in the actual electrode area of the 3-D capacitor since the total stored charges are proportional to the capacitor area. Fig. 8(e) shows the ESD and ESE of the fabricated ...
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... by polarization per footprint unit. As shown in Fig. 8(d), compared with the planar capacitor, the polarization per footprint unit for the 3-D trench capacitor greatly increases, which is attributed to a significant increase in the actual electrode area of the 3-D capacitor since the total stored charges are proportional to the capacitor area. Fig. 8(e) shows the ESD and ESE of the fabricated 3-D capacitor under different electric field. As the electric field increases from 1 to 5.7 MV/cm, the ESD increases gradually from 6.45 to 358.14 J/cm 3 , however, the ESE decreases from 95% to 56%. In particular, when the electric field is larger than 3 MV/cm, the ESE exhibits a remarkable ...
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... larger than 3 MV/cm, the ESE exhibits a remarkable decrease. This is because the enlarged P-E hysteresis loop leads to a larger hysteresis loss. To evaluate the uniformity of the fabricated 3-D capacitors, 30 devices are measured in comparison with the planar capacitors. The Weibull distributions of the extracted maximum ESD and ESE are shown in Fig. 8(f). It is found that the 3-D capacitors demonstrate a mean ESD of 364.1 J/cm 3 , which is around five times that (71.95 J/cm 3 ) for the planar capacitors. In addition, although the planar capacitors display excellent electrical uniformity, the 3-D capacitors also have a quite narrow distribution of maximum ESD. On the other hand, both ...
Citations
... 421 Figure 19 represents the best-performing ES parameters for different The capacitors also showed a stable operation of up to 150 ○ C and 10 6 cycles. 425 In addition, a giant ESD of 109 J cm −3 with an efficiency >95% was obtained with a new concept of negative-capacitance, in which Hf 0.5 Zr 0.5 O 2 and a Ta 2 O5 layer are combined. 110 Moreover, a stable operation of up to 150 ○ C and 10 8 charging/discharging cycles was demonstrated. ...
... 383 Moreover, by integrating the FE-Hf 0.5 Zr 0.5 O 2 (1 nm)/AFE-Hf 0.25 Zr 0.75 O 2 (9 nm) bilayered capacitor into deep silicon trenches, an enhancement of the ESD from 71.95 up to 364.1 J cm −3 was achieved. 425 In addition, from the Weibull distributions of the extracted maximum ESD and efficiency, it is possible to conclude that while the planar capacitors display excellent electrical uniformity, the 3D capacitors have a narrow distribution of maximum ESD. On the other hand, both the planar and 3D capacitors exhibit very close efficiencies, corresponding to 57.8% and 56.5%, respectively. ...
Ferroelectric hafnium and zirconium oxides have undergone rapid scientific development over the last decade, pushing them to the forefront of ultralow-power electronic systems. Maximizing the potential application in memory devices or supercapacitors of these materials requires a combined effort by the scientific community to address technical limitations, which still hinder their application. Besides their favorable intrinsic material properties, HfO2–ZrO2 materials face challenges regarding their endurance, retention, wake-up effect, and high switching voltages. In this Roadmap, we intend to combine the expertise of chemistry, physics, material, and device engineers from leading experts in the ferroelectrics research community to set the direction of travel for these binary ferroelectric oxides. Here, we present a comprehensive overview of the current state of the art and offer readers an informed perspective of where this field is heading, what challenges need to be addressed, and possible applications and prospects for further development.
... Further, in combination with good reliability, excellent thermal stability and eco-friendly properties, the doped HfO 2 AFE dielectrics are considered to be very promising materials for on-chip energy storage applications [8]. To improve the ESD of capacitors, our recent studies indicate that the employment of a 1 nm Hf 0.5 Zr 0. 5 O 2 underlying layer between the bottom electrode and the AFE Hf 0.25 Zr 0.75 O 2 layer can promote the generation of the AFE tetragonal (T)-phase in the AFE layer [9]. In addition, Yang et al. reported a HfO 2 /ZrO 2 nanolaminate with a 2.2 nm HfO 2 thin film as the insertion layer between the TiN bottom electrode and ZrO 2 AFE thin film and achieved an ESD of up to 49.9 J cm −3 [10]. ...
... In addition, the formation of the extra O-(111) phase may be responsible for the decrease in the ESD in the sample with the Al/(Hf + Zr) ratio of 1/24 due to the reduction in the relative proportion of the T-phase. Table 1 compares our work with other HfO 2 -based AFE capacitors [5][6][7]9,10,13,14,21,22]. It is observed that our capacitor with the Al/(Hf + Zr) ratio of 1/16 demonstrates the highest ESD at 6 MV cm −1 together with a perfect ESE. ...
Concurrently achieving high energy storage density (ESD) and efficiency has always been a big challenge for electrostatic energy storage capacitors. In this study, we successfully fabricate high-performance energy storage capacitors by using antiferroelectric (AFE) Al-doped Hf0.25Zr0.75O2 (HfZrO:Al) dielectrics together with an ultrathin (1 nm) Hf0.5Zr0.5O2 underlying layer. By optimizing the Al concentration in the AFE layer with the help of accurate controllability of the atomic layer deposition technique, an ultrahigh ESD of 81.4 J cm−3 and a perfect energy storage efficiency (ESE) of 82.9% are simultaneously achieved for the first time in the case of the Al/(Hf + Zr) ratio of 1/16. Meanwhile, both the ESD and ESE exhibit excellent electric field cycling endurance within 109 cycles under 5~5.5 MV cm−1, and robust thermal stability up to 200 °C. Thus, the fabricated capacitor is very promising for on-chip energy storage applications due to favorable integratability with the standard complementary metal–oxide–semiconductor (CMOS) process.
... [1,2] Recently, rapidly increased demands of miniaturization and integration continuously challenge energy storage density of dielectric capacitors, especially for that could be compatible with the complementary metal-oxide-semiconductor (CMOS) technology, for developing energy-autonomous systems and implantable/wearable electronics, where high-κ capacitors become increasingly desirable in the next-generation applications. [3][4][5] However, their recoverable energy storage densities (U rec ) are low in emerging capacitive energy storage materials. Here, by structure evolution between fluorite HfO 2 and perovskite hafnate who have similar metal sublattices, we create an amorphous hafnium-based oxide that exhibits a giant U rec of ~155 J/cm 3 Fig. ...
Dielectric capacitors are fundamental for electric power systems due to the fast charging/discharging rate and high-power density. [1,2] Recently, rapidly increased demands of miniaturization and integration continuously challenge energy storage density of dielectric capacitors, especially for that could be compatible with the complementary metal-oxide-semiconductor (CMOS) technology, for developing energy-autonomous systems and implantable/wearable electronics, where high-κ capacitors become increasingly desirable in the next-generation applications. [3-5] However, their recoverable energy storage densities ( U rec ) are low in emerging capacitive energy storage materials. Here, by structure evolution between fluorite HfO 2 and perovskite hafnate who have similar metal sublattices, we create an amorphous hafnium-based oxide that exhibits a giant U rec of ~155 J/cm ³ with an efficiency (η) of 87%, which is record-high in high-κ materials and state-of-the-art in dielectric energy storage. The improved energy density is owing to the strong structure disordering in both short and long ranges induced by oxygen instability in between the two energetically-favorable crystalline forms. As a result, the carrier avalanche is impeded and an ultrahigh breakdown strength ( E b ) up to 12 MV/cm is achieved, which, accompanying with a large permittivity (ε r ), remarkably enhances the dielectric energy storage. Our study provides a new and widely applicable playground for designing high-performance dielectric energy storage with the strategy exploring the boundary among different categories of materials.
Current microelectronic technology is highly desired to addressing chip power instability and micro-overheating in highly integrated devices utilizing a single material. For this purpose, we propose an efficient strategy by...
Dielectric electrostatic capacitors¹, because of their ultrafast charge–discharge, are desirable for high-power energy storage applications. Along with ultrafast operation, on-chip integration can enable miniaturized energy storage devices for emerging autonomous microelectronics and microsystems2–5. Moreover, state-of-the-art miniaturized electrochemical energy storage systems—microsupercapacitors and microbatteries—currently face safety, packaging, materials and microfabrication challenges preventing on-chip technological readiness2,3,6, leaving an opportunity for electrostatic microcapacitors. Here we report record-high electrostatic energy storage density (ESD) and power density, to our knowledge, in HfO2–ZrO2-based thin film microcapacitors integrated into silicon, through a three-pronged approach. First, to increase intrinsic energy storage, atomic-layer-deposited antiferroelectric HfO2–ZrO2 films are engineered near a field-driven ferroelectric phase transition to exhibit amplified charge storage by the negative capacitance effect7–12, which enhances volumetric ESD beyond the best-known back-end-of-the-line-compatible dielectrics (115 J cm⁻³) (ref. ¹³). Second, to increase total energy storage, antiferroelectric superlattice engineering¹⁴ scales the energy storage performance beyond the conventional thickness limitations of HfO2–ZrO2-based (anti)ferroelectricity¹⁵ (100-nm regime). Third, to increase the storage per footprint, the superlattices are conformally integrated into three-dimensional capacitors, which boosts the areal ESD nine times and the areal power density 170 times that of the best-known electrostatic capacitors: 80 mJ cm⁻² and 300 kW cm⁻², respectively. This simultaneous demonstration of ultrahigh energy density and power density overcomes the traditional capacity–speed trade-off across the electrostatic–electrochemical energy storage hierarchy1,16. Furthermore, the integration of ultrahigh-density and ultrafast-charging thin films within a back-end-of-the-line-compatible process enables monolithic integration of on-chip microcapacitors⁵, which can unlock substantial energy storage and power delivery performance for electronic microsystems17–19.
The emergence of ferroelectric and antiferroelectric properties in the semiconductor industry's most prominent high‐k dielectrics, HfO2 and ZrO2, is leading to technology developments unanticipated a decade ago. Yet the failure to clearly distinguish ferroelectric from antiferroelectric behavior is impeding progress. Band‐excitation piezoresponse force microscopy and molecular dynamics are used to elucidate the nanoscale electric field‐induced phase transitions present in ZrO2‐based antiferroelectrics. Antiferroelectric ZrO2 is clearly distinguished from a closely resembling pinched La‐doped HfO2 ferroelectric. Crystalline grains in the range of 3 – 20 nm are imaged independently undergoing reversible electric field induced phase transitions. The electrically accessible nanoscale phase transitions discovered in this study open up an unprecedented paradigm for the development of new nanoelectronic devices.
Recently, rapidly increased demands of integration and miniaturization continuously challenge energy densities of dielectric capacitors. New materials with high recoverable energy storage densities become highly desirable. Here, by structure evolution between fluorite HfO2 and perovskite hafnate, we create an amorphous hafnium-based oxide that exhibits the energy density of ~155 J/cm³ with an efficiency of 87%, which is state-of-the-art in emergingly capacitive energy-storage materials. The amorphous structure is owing to oxygen instability in between the two energetically-favorable crystalline forms, in which not only the long-range periodicities of fluorite and perovskite are collapsed but also more than one symmetry, i.e., the monoclinic and orthorhombic, coexist in short range, giving rise to a strong structure disordering. As a result, the carrier avalanche is impeded and an ultrahigh breakdown strength up to 12 MV/cm is achieved, which, accompanying with a large permittivity, remarkably enhances the energy storage density. Our study provides a new and widely applicable platform for designing high-performance dielectric energy storage with the strategy exploring the boundary among different categories of materials.
