Papers by Keyword: Hafnium Oxide

Abstract: This research paper investigates the application of a Double Gate (DG) Tunnel Field-Effect Transistor (DG-TFET) for the detection of cell lines derived from breast cancer tissue, namely Hs578T, MDA-MB-231, MCF-7, and T47D. The device incorporates two nanocavities positioned beneath the two gate electrodes, significantly enhancing detection capabilities. The study emphasizes the differentiation between healthy non-tumorigenic cells (MCF-10A) and breast cancer-derived cell lines by incorporating gate engineering into the TFET. Furthermore, the research explores the impact of changes in dielectric values specific to different breast malignant cell types on the biosensor's detection capabilities. Additionally, the investigation delves into the influence of variations in device geometry, including cavity dimensions and dielectric layer thickness, on critical parameters such as drain current sensitivity, transconductance sensitivity, and ION/IOFF sensitivity. Sensitivity analysis concerns drive current, ION/IOFF ratio, threshold voltage (Vth), and transconductance. The structural design of the device is tailored to facilitate array-based diagnosis and screening of cell lines derived from breast cancer tissue. This design offers several advantages, including a simplified transduction process, compatibility with CMOS processes, cost-effectiveness, reproducibility, and adjustable electrical responses. The researchers employed ATLAS, a two-dimensional (2D) device simulator from Silvaco, to model and define the device structure. The numerical simulations validate the device's performance, demonstrating favorable ON-OFF transition profiles.

Abstract: Different material thickness with medium and high dielectric constant can impact the performance and reliability of high electron mobility transistor device. With varying the thickness of the passivation layer, the effect of it towards the device performance is still unclear. Two different insulator layers with a medium dielectric and a high dielectric constant namely Aluminium Nitride and Hafnium Oxide are used as passivation layer in AlGaN/GaN HEMT. Both material performance was simulated via COMSOL software by varying the thickness and the drain current output were compared. The passivation layer thickness of 10nm at V_ds=6 V and V_gs=5 V, HfO₂ outperforms AlN with the output drain current of 39 mA compared to 35 mA respectively. It was observed that HfO₂ can attain higher threshold voltage, V_th as compared to the AlN because of the influence of its material properties that shows a direct proportional relationship between V_th and dielectric constant. Using high dielectric constant material like HfO₂, we observe the ON-voltage gradually decreases as the thickness of the passivation layer increased. Out of all the thickness simulated for HfO₂ and AlN, 10nm produced the highest drain current output instead of layer thickness of 20nm.

Abstract: In this work, we synthesize Hafnium (IV) oxide (HfO₂) ink from hafnium chloride (HfCl₄) powder assisted with deionized water. The poly acrylic acid (PAA) is used as surfactant to decrease the surface tension. Conversion of HfCl₄ into HfO₂ was detected by Raman spectroscopy and energy dispersive X-ray spectroscopy (EDS) characterization techniques. This proposed ink can be easily synthesized at a low temperature. Using the synthesis ink, a liquid capacitor is proposed, which is tested for electrochemical analysis. Indium tin oxide (ITO) coated PET is used as bottom and top current collector electrode, polydimethylsiloxane (PDMS) mold is used as separator, and HfO₂ ink is used as aqueous electrolyte. Liquid capacitor is also tested on different bending diameters using bending machine from flat down to 10 mm bending curvature, which shows a stable capacitor function.

Abstract: Hafnium oxide (HfO₂) is a material characterized by a good mechanical, thermal and chemical stability and is used as a material in a variety of technological applications in optics and electronics. In this work the influence of annealing temperature on the mechanical structural properties of amorphous HfO₂ thin film was explored. Films were deposited by electron beam evaporation and annealed in the temperature range from 200 °C to 500 °C in vacuum. Mechanical properties such as hardness and elastic modulus were determined using nanoindentation, while cohesive-adhesive properties of the film using a scratch test. Surface morphology was determined using a confocal microscope and structure using XRD. The transformation of amorphous phase of the films to the nanocrystalline monoclinic phase was observed after vacuum annealing at 500 °C. This crystallization leads to increase in hardness on one hand but also to growth of brittleness and in turn to decrease in scratch resistance on the other hand.

Abstract: High-k gate dielectrics and metal gate electrodes have become essential for emerging device technologies because they enable the continuous scaling down of devices while maintaining a high performance [. However, since they are composed of novel metallic elements that have never before been used in conventional processes, special care must be taken when handling these materials in the production line. In particular, cross-contamination that occurs due to transporting contamination via processed wafers can cause serious problems such as deterioration of device properties and yield loss [. The process of cleaning the backside and bevel of a wafer is now increasingly important for avoiding these problems. To date, there has been no detailed evaluation of contamination removal on various films performed for elements such as hafnium, which is one of the key elements in high-k/metal gate technologies. In this study, we evaluated hafnium contamination on three types of wafer surface after the cleaning process and investigated the cause of different residual amounts of hafnium contamination on the different wafers.

Abstract: Hafnium oxide thin films were deposited on silicon substrates by RF reactive magnetron sputtering. The effects of oxygen partial pressure, tuned by the O2/Ar flow ratio, on the microstructure and electrical properties were characterized. All HfOx thin films exhibit monoclinic phases. As the increase of O2/Ar flow ratio from 0.08 to 0.33, the crystallinity is improved accompanied with the decreases of flat band voltage and leakage current density. However, when the O2/Ar flow ratio further increases to 0.5, the crystallinity becomes worse with the increase of flat band voltage and leakage current. The HfOx based resistive random-access memory (RRAM) has been fabricated and its storage properties were also investigated.

Abstract: Transmission electron microscopy (TEM) techniques were used for characterization of annealing (400, 600 and 800 °C) influence on the structural properties of the HfO₂ film (45 nm thick) deposited on Si substrate. Such structures are considered as high-k dielectric materials for application in novel semiconductor devices. The studies showed that independently of the annealing temperature a very thin and flat amorphous layer is formed between HfO₂ layer and Si substrate. This result was also found in the non-annealed sample. EDXS examination confirmed that the stoichiometry for the hafnium oxide layer in each sample corresponds to 1:2 for Hf:O (i.e. to HfO₂). TEM images revealed differences in the microstructure of HfO₂ layers in annealed samples, however the layers have similar thickness and interface roughness in all studied samples.

Abstract: In this work we report on the structural and electrical properties of SiO₂/Si3N₄/HfO₂ memory stacks with emphasis upon the influence of Atomic Layer Deposition chemistry used for forming the HfO₂ blocking layer. Two HfO₂ precursor chemistries were employed, the tetrakis- (ethylmethylamino)hafnium (TEMAH) and the bis(methylcyclopentadienyl)methoxymethylhafnium (HfD-04). Ozone was used as the oxygen source. The structural characteristics of the stacks were examined by means of TEM and GIXRD. Comparative studies conducted with the use of platinum gated capacitors showed that the samples grown using TEMAH have an increased electron trapping ability in comparison to the HfD-04 ones. While the two structures exhibit similar Write/Erase and retention characteristics, The samples grown from TEMAH can sustain more repeated W/E cycles (> 3×10⁵ in the 10V/-11V, 10 ms regime) compared to the samples grown from HfD-04 (< 10⁴ W/E cycles). This difference in endurance characteristics is attributed mainly to the different deposition temperatures used with these two precursors and the nature of the interfacial layer they produce between the Si₃N₄ and the HfO₂ layers.

Abstract: In this paper, the integration of HfO2 onto SiC has been investigated via a number of different test structures. Capacitors consisting of HfO2 on Si, SiC, Si/SiC and SiO2/SiC have been fabricated and electrically tested. The new HfO2/Si/SiC capacitors provide the greatest breakdown electric field of 3.5 MV/cm, whilst leakage currents are minimised through the insertion of the narrow bandgap material. The Si layer, which is wafer bonded to the SiC, is proven to be stress free through Raman spectroscopy, whilst TEM and EDX prove that the interface is free of contaminants.

Abstract: In this chapter Perturbed Angular Correlation (PAC) experiments on binary oxides are described. These experiments provide local-scale fingerprints about the formation, identification, and lattice environment of defect complexes at the PAC probe site. The potential of the PAC observations in conjunction with ab initio calculations is shown. Measurements of the electric-field gradient at impurity sites using ¹¹¹Cd and ¹⁸¹Ta probes are reviewed. Special attention is paid to oxides with the bixbyite structure. The case of In₂O₃ is particularly analyzed. Results obtained with HfO₂, in form of coarse grain or nano particles, are described. The potential results that can be obtained from Density Functional Theory ab initio calculations in doped systems are shown describing the main results observed in many impurity-host systems.