Rapid Thermal Research Articles

The Effect of Nitrogen Concentration at Oxynitride Gate Insulators Formed by 28N2 + Implantation into Silicon with Additional Conventional or Rapid Thermal Oxidation

Silicon oxynitride (SiOxNy) insulators have been obtained by nitrogen ion implantation into Si substrates prior to conventional or rapid thermal oxidation. These films have been used as gate insulators in nMOSFETs and MOS capacitors. nMOSFET electrical characteristics, such as field effect mobility between 390 cm2/Vs and 530 cm2/Vs, and sub-threshold slope between 70 mV/decade and 150 mV/decade, were obtained. MOS capacitors were used to obtain capacitance-voltage (C-V) and current-voltage (I-V) measurements. The Equivalent Oxide Thickness (EOT) of the films were obtained from C-V curves, resulting in values between 2.9 nm and 12 nm. SiOxNy gate insulators with EOT between 2.9 nm and 4.3 nm have presented gate leakage current densities between 3 mA/cm2 and 50 nA/cm2. The electrical characteristics were compared and correlated with the nitrogen concentration profiles at SiOxNy/Si of the structures, obtained by Secondary Ion Mass Spectrometry (SIMS).

Micro–Nanostructured TiN Thin Film: Synthesis from a Photo-Patternable TiO2 Sol–Gel Coating and Rapid Thermal Nitridation

The miniaturization of optical components to control and manipulate light amplitude, phase, and polarization requires micro- to nanostructured metasurfaces that provide resonant light–matter intera...

Rapid Thermal Annealing of Double Perovskite Thin Films Formed by Polymer Assisted Deposition.

The annealing process is an important step common to epitaxial films prepared by chemical solution deposition methods. It is so because the final microstructure of the films can be severely affected by the precise features of the thermal processing. In this work we analyze the structural and magnetic properties of double perovskite La2CoMnO6 and La2NiMnO6 epitaxial thin films prepared by polymer-assisted deposition (PAD) and crystallized by rapid thermal annealing (RTA). It is found that samples prepared by RTA have similar values of saturation magnetization and Curie temperature to their counterparts prepared by using conventional thermal annealing (CTA) processes, thus indicating low influence of the heating rates on the B-B’ site cationic ordering of the A2BB’O6 double perovskite structure. However, a deeper analysis of the magnetic behavior suggested some differences in the actual microstructure of the films.

Atomic‐Layer‐Deposited Al2O3 as Effective Barrier against the Diffusion of Hydrogen from SiNx:H Layers into Crystalline Silicon during Rapid Thermal Annealing

Stacks of hydrogen‐lean aluminum oxide, deposited via plasma‐assisted atomic‐layer‐deposition, and hydrogen‐rich plasma‐enhanced chemical vapor‐deposited silicon nitride (SiNx) are applied to boron‐doped float‐zone silicon wafers. A rapid thermal annealing (RTA) step is performed in an infrared conveyor‐belt furnace at different set‐peak temperatures. The hydrogen content diffused into the crystalline silicon during the RTA step is quantified by measurements of the silicon resistivity increase due to hydrogen passivation of boron dopant atoms. These experiments indicate that there exists a temperature‐dependent maximum in the introduced hydrogen content. The exact position of this maximum depends on the composition of the SiNx layer. The highest total hydrogen content, exceeding 1015 cm−3, is introduced into the silicon bulk from silicon‐rich SiNx layers with a refractive index of 2.3 (at λ = 633 nm) at an RTA peak temperature of 800 °C, omitting the Al2O3 interlayer. Adding an Al2O3 interlayer with a thickness of 20 nm reduces the hydrogen content by a factor of four, demonstrating that Al2O3 acts as a highly effective hydrogen diffusion barrier. Measuring the hydrogen content in the silicon bulk as a function of Al2O3 thickness at different RTA peak temperatures provides the hydrogen diffusion length in Al2O3 as a function of measured temperature.

Investigation of laser‐produced plasma multistructuring by floating probe measurements and optical emission spectroscopy

AbstractWith the continuous development of pulsed laser deposition as a versatile technique for the deposition of complex thin films, there is a need for a better understanding of the role and control of the deposition parameters. The understanding of the particle kinetics and plasma chemistry during the deposition process can greatly improve the properties of the synthesized films. By using the floating voltage regime of the Langmuir probe technique, we performed angular and time‐resolved measurements during laser ablation of an Ag target, which evidenced the structuring of the plasma plume in ultrahigh vacuum conditions. The addition of N2 gas in the pressure range from 5 × 10–5 to 10 Pa leads to more rapid plasma thermalization and the control of its kinetic energy. The electrical measurements were complemented by optical emission spectroscopy, which showcased the presence of neutral and multiple ionized species distributed across the laser‐produced plasma plume. The plasma homogenization resulted in a decrease of the mean free path of Ag ions and atoms, which increased both their excitation temperature and electron density.

Rapid Thermal Annealing for Ag Layers on SiO2 Coated Metal Foils

Rapid Thermal Annealing for Ag Layers on SiO2 Coated Metal Foils

Enhanced Optical 13C Hyperpolarization in Diamond Treated by High‐Temperature Rapid Thermal Annealing

Abstract Methods of optical dynamic nuclear polarization open the door to the replenishable hyperpolarization of nuclear spins, boosting their nuclear magnetic resonance/imaging signatures by orders of magnitude. Nanodiamond powder rich in negatively charged nitrogen vacancy defect centers has recently emerged as one such promising platform, wherein 13C nuclei can be hyperpolarized through the optically pumped defects completely at room temperature. Given the compelling possibility of relaying this 13C polarization to nuclei in external liquids, there is an urgent need for the engineered production of highly “hyperpolarizable” diamond particles. Here, a systematic study of various material dimensions affecting optical 13C hyperpolarization in diamond particles is reported on. It is discovered surprisingly that diamond annealing at elevated temperatures ∼1720 °C has remarkable effects on the hyperpolarization levels enhancing them by above an order of magnitude over materials annealed through conventional means. It is demonstrated these gains arise from a simultaneous improvement in NV− electron relaxation/coherence times, as well as the reduction of paramagnetic content, and an increase in 13C relaxation lifetimes. This work suggests methods for the guided materials production of fluorescent, 13C hyperpolarized, nanodiamonds and pathways for their use as multimodal (optical and magnetic resonance) imaging and hyperpolarization agents.

Multi-stack insulator to minimise threshold voltage drift in ZnO FET sensors operating in ionic solutions

FET biosensors operating in an electrolyte experience a monotonic, temporal and relatively slow change in threshold voltage caused by the hydration of the insulator layer between the electrolyte and the FET's channel. Minimising this temporal change in threshold voltage is critical as, over time, the drain current of n-channel FETs decreases, making it difficult to distinguish between the signal generated in response to analyte - receptor binding events and the background noise generated by the electrolyte and the FET biosensor. While Rapid Thermal Annealing of the insulator layer is known to diminish threshold voltage drift and its negative effects, it is not compatible with a low temperature fabrication process of 200oC. Our low temperature approach to minimising threshold voltage drift involves depositing a tri-layer insulator stack, consisting of a layer of HfO2 between two Al2O3 layers. Wetting ZnO NWFETs with PBS (10 mM phosphate, 150 mM KCl, pH 7.4) for an hour, showed that ZnO NWFETs with a stack insulator layer experienced a much smaller threshold voltage and drain current drift (100 mV, 0.064 nA) than ZnO NWFETs with a single material insulator layer (≥4300mV, 2.72 nA), Aluminium oxide in this case. Having established the resilience enhancing properties of the stack insulator layer on FETs operating in electrolytes of physiological relevant ionic concentrations; ZnO NWFETs with a stack insulator layer were shown to be capable of detecting the presence of the miDNA-21 strands. This, in effect, paves the way for miRNA sensing experiments in the near future and for exploring the potential of ZnO NWFETs as a diagnostic tool.

Performance Enhancement of Channel-Engineered Al–Zn–Sn–O Thin-Film Transistors with Highly Conductive In–Ga–Zn–O Buried Layer via Vacuum Rapid Thermal Annealing

In this study, we propose, fabricate, and examine the electrical characteristics of high-performance channel-engineered amorphous aluminum-doped zinc tin oxide (a-AZTO) thin-film transistors (TFTs). Amorphous indium gallium zinc oxide (a-IGZO) film with improved conductivity (obtained via rapid thermal annealing in vacuum) is applied as the local conductive buried layer (LCBL) of the channel-engineered a-AZTO TFTs. The optical transmittance of the a-IGZO and a-AZTO films in the visible region is >85%. The a-IGZO LCBL reduces the resistance of the a-AZTO channel, thereby resulting in increased drain current and improved device performance. We find that our fabricated channel-engineered a-AZTO TFTs with LCBLs are superior to non-channel-engineered a-AZTO TFTs without LCBLs in terms of electrical properties such as the threshold voltage, mobility, subthreshold swing, and on-off current ratios. In particular, as the a-IGZO LCBL length at the bottom of the channel increases, the channel resistance gradually decreases, eventually resulting in a mobility of 22.8 cm²/V · s, subthreshold swing of 470 mV/dec, and on-off current ratio of 3.98×107. We also investigate the effect of the a-IGZO LCBL on the operational reliability of a-AZTO TFTs by measuring the variation in the threshold voltage for positive gate bias temperature stress (PBTS), negative gate bias temperature stress (NBTS), and negative gate bias temperature illumination stress (NBTIS). The results indicate that the TFT instability for temperature and light is not affected by the LCBL. Therefore, our proposed channel-engineered a-AZTO TFT can form a promising high-performance high-reliability switching device for next-generation displays.

The Ohmic Contact of 4H-SiC Power Devices by Pulse Laser Annealing and Rapid Thermal Annealing

The preparation of ohmic contact with high stability and low resistance is critical, and the quality of ohmic contact will directly affect the performance of devices as the efficiency, gain and switching speed. In this work, the I-V characteristic of the 4H-SiC devices under rapid thermal annealing and pulsed laser annealing were compared, the pulsed laser annealing process could obtain the lower ohmic contact resistant. The surface morphology, material composition, and elemental analysis were clarified by optical microscopy (OM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS), respectively. This research suggests that more Ni2Si and carbon vacancy can form at the interface under pulsed laser annealing.

Fabrication of Germanium-on-insulator in a Ge wafer with a crystalline Ge top layer and buried GeO2 layer by oxygen ion implantation

The paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by Oxygen ion implantation of an undoped Ge wafer of orientation (100). O+ ions (energy 200 keV) were implanted to a fluence of 1.9 × 1018 ions-cm−2 and the implanted wafer was subjected to Rapid Thermal Annealing. The resulting wafer has a top crystalline Ge layer of ~ 220 nm thickness and resistivity ≈32 Ohm-cm and a buried Oxide layer (BOX) of crystalline GeO2 (thickness ≈0.62 μm). The crystalline GeO2 layer has hexagonal crystal structure with lattice constants close to the standard values. Raman Spectroscopy and cross-sectional electron microscopy established that the top Ge layer was recrystallized during annealing with a residual tensile strain of around +0.4% and an estimated dislocation density of 2.7 × 107cm−2. The crystallinity and electrical characteristics of the top layer and the quality of the BOX layer are such that it can be utilized for device fabrication.

Restoring coherence via aperiodic drives in a many-body quantum system

We study the unitary dynamics of randomly or quasi-periodically driven tilted Bose-Hubbard (tBH) model in one dimension deep inside its Mott phase starting from a $\mathbb{Z}_2$ symmetry-broken state. The randomness is implemented via a telegraph noise protocol in the drive period while the quasi-periodic drive is chosen to correspond to a Thue-Morse sequence. The periodically driven tBH model (with a square pulse protocol characterized by a time period $T$) is known to exhibit transitions from dynamical regimes with long-time coherent oscillations to those with rapid thermalization. Here we show that starting from a regime where the periodic drive leads to rapid thermalization, a random drive, which consists of a random sequence of square pulses with period $T+\alpha dT$, where $\alpha=\pm 1$ is a random number and $dT$ is the amplitude of the noise, restores long-time coherent oscillations for special values of $dT$. A similar phenomenon can be seen for a quasi-periodic drive following a Thue-Morse sequence where such coherent behavior is shown to occur for a larger number of points in the $(T, dT)$ plane due to the additional structure of the drive protocol. We chart out the dynamics of the system in the presence of such aperiodic drives, provide a qualitative analytical understanding of this phenomenon, point out the role of quantum scars behind it, and discuss experiments which can test our theory.

Vertical MOS and tunnel FETs in the same silicon pillar structure with Al and TiN gate electrodes

This work presents a silicon pillar structure containing both MOS (Metal-Oxide-Semiconductor) and Tunnel Field Effect Transistors (MOSFETs and TFETs, respectively) with Al and TiN double-gate electrodes. The abrupt n+ regions of drain/source in the p-Si vertical pillar are obtained from sequential 31P+ ion implantations (energies of 100, 50 and 25 keV) and Rapid Thermal Annealing (RTA). The abrupt drain region in the p-Si pillar allows the vertical control of the channel length of the MOSFET device (achieving lengths such as 70 nm) and the formation of a nano-intrinsic region (2 nm), between n+ and p regions, fundamental for the operation of a TFET. The MOSFETs and TFETs, which were fabricated with Al gate, have presented the better results (Ion of 56 μA/μm, gm of 45 μS/μm and (Ion/Ioff) ratio of 107) related to higher performance in conduction regime. However, both devices, fabricated with TiN, have presented higher performance related to leakage and/or off current (Ioff of 1.8 pA/μm). It is important to notice that the alternating use at the same silicon pillar for the both MOSFET or TFET devices can be suitable to the applications in which are necessary high and low power operations, respectively.

Pauli blocking effects in thermalization of relativistic plasma

We investigate the effects of Pauli blocking on thermalization process of relativistic plasma by solving relativistic Uehling-Uhlenbeck equations with QED collision integral for all binary and triple processes. With this purpose we consider nonequilibrium initial state of plasma to be strongly degenerate. We found that when electron-positron annihilation is efficient, initial plasma degeneracy is quickly destroyed. As a result in a wide range of final temperatures ranging from nonrelativistic to mildly relativistic 0.1mec2≤kBT≤10mec2 thermalization is not affected by Pauli blocking. Conversely, when electron-positron annihilation process is inefficient, thermalization process in such degenerate plasma is strongly affected by Pauli blocking. This is possible either in a nonrelativistic plasma, with equilibrium temperature kBT≤0.3mec2, or in photon-electron plasma. In these cases all reaction rates are strongly suppressed by Pauli blocking and thermalization does not occur until electrons can populate energy states above the Fermi energy. Soon after this happens thermalization proceeds suddenly in an avalanche-like process. Such rapid thermalization can be a unique footprint of strongly degenerate plasma.

Imprinting the Polytype Structure of Silicon Carbide by Rapid Thermal Processing

Silicon carbide is a material with a multistable crystallographic structure, i.e., a polytypic material. Different polytypes exhibit different band gaps and electronic properties with nearly identical basal plane lattice constants, making them interesting for heterostructures without concentration gradients. The controlled formation of this heterostructure is still a challenge. The ability to adjust a defined temperature–time profile using rapid thermal processing was used to imprint the polytype transitions by controlling the nucleation and structural evolution during the temperature ramp-up and the steady state. The influence of the linear heating-up rate velocity during ramp-up and steady-state temperature on the crystal structure of amorphized ion-implanted silicon carbide layers was studied and used to form heteropolytype structures. Integrating the structural selection properties of the non-isothermal annealing stage of the ion-implanted layers into an epitaxial growth process allows the imprinting of polytype patterns in epitaxial layers due to the structural replication of the polytype pattern during epitaxial growth. The developed methodology paves the way for structural selection and vertical and lateral polytype patterning. In rapid thermal chemical vapor deposition, the adjustment of the process parameters or the buffer layer allowed the nucleation and growth of wurtzite silicon carbide.

Collapse and revival of quantum many-body scars via Floquet engineering

The presence of quantum scars, athermal eigenstates of a many-body Hamiltonian with finite energy density, leads to absence of ergodicity and long-time coherent dynamics in closed quantum systems starting from simple initial states. Such non-ergodic coherent dynamics, where the system does not explore its entire phase space, has been experimentally observed in a chain of ultracold Rydberg atoms. We show, via study of a periodically driven Rydberg chain, that the drive frequency acts as a tuning parameter for several reentrant transitions between ergodic and non-ergodic regimes. The former regime shows rapid thermalization of correlation functions and absence of scars in the spectrum of the system's Floquet Hamiltonian. The latter regime, in contrast, has scars in its Floquet spectrum which control the long-time coherent dynamics of correlation functions. Our results open a new possibility of drive frequency-induced tuning between ergodic and non-ergodic dynamics in experimentally realizable disorder-free quantum many-body systems.

Formulation of Sugar/Hydrogel Inks for Rapid Thermal Response 4D Architectures with Sugar-derived Macropores

Programmed, reshaping hydrogel architectures were fabricated from sugar/hydrogel inks via a three-dimensional printing method involving a stimuli-responsive polymer. We developed a new hydrogel ink composed of monomers (acrylamide [AAm]) and N-isopropylacrylamide [NIPAAm]), and sugar (mixture of glucose and sucrose) as a pore-generator, enabling to improve printability by increasing the ink’s viscoelastic properties and induce the formation of macropores in the hydrogel architectures. This study demonstrated that creating macropores in such architectures enables rapid responses to stimuli that can facilitate four-dimensional printing. We printed bilayer structures from monomer inks to which we had added sugar, and we exposed them to processes that cross-linked the monomers and leached out the sugar to create macropores. In comparison with a conventional poly(N-isopropylacrylamide) hydrogel, the macroporous hydrogels prepared using polymerization in the presence of a high concentration of sugar showed higher swelling ratios and exhibited much faster response rates to temperature changes. We used rheometry and scanning electron microscopy to characterize the properties of these inks and hydrogels. The results suggest that this method may provide a readily available route to the rapid design and fabrication of shape-morphing hydrogel architectures with potential application in soft robotics, hydrogel actuators, and tissue engineering.

WITHDRAWN: Multi-stack insulator to minimise threshold voltage drift in ZnO FET sensors operating in ionic solutions

Abstract FET biosensors operating in an electrolyte experience a monotonic, temporal and relatively slow change in threshold voltage caused by the hydration of the insulator layer between the electrolyte and the FET's channel. Minimising this temporal change in threshold voltage is critical as, over time, the drain current of n-channel FETs decreases, making it difficult to distinguish between the signal generated in response to analyte - receptor binding events and the background noise generated by the electrolyte and the FET biosensor. While Rapid Thermal Annealing of the insulator layer is known to diminish threshold voltage drift and its negative effects, it is not compatible with a low temperature fabrication process of 200 °C. Our low temperature approach to minimising threshold voltage drift involves depositing a tri-layer insulator stack, consisting of a layer of HfO2 between two Al2O3 layers. Wetting ZnO NWFETs with PBS (10 mM phosphate, 150 mM KCl, pH 7.4) for an hour, showed that ZnO NWFETs with a stack insulator layer experienced a much smaller threshold voltage and drain current drift (100 mV, 0.064 nA) than ZnO NWFETs with a single material insulator layer (≥4300mV, 2.72 nA), Aluminium oxide in this case. Having established the resilience enhancing properties of the stack insulator layer on FETs operating in electrolytes of physiological relevant ionic concentrations; ZnO NWFETs with a stack insulator layer were shown to be capable of detecting the presence of the miDNA-21 strands. This, in effect, paves the way for miRNA sensing experiments in the near future and for exploring the potential of ZnO NWFETs as a diagnostic tool.

Study of Si(100)-SiO2 Interface Trap Time Constant Distributions in Large Area Conventional MOSFETs-Comparison with Submicron Devices

It seems well accepted now that Pb0 centers are the main defects at the Si(100)/SiO2 interface in conventional MOS transistors, even after forming annealing.Besides, the charge pumping (CP) technique in which a MOSFET is repeatedly switched between inversion and accumulation has been widely used for studying single capture/emission events in deep submicron transistors [1]. In CP, the minority carriers stored into the interface traps in inversion recombine in accumulation with majority carriers from the substrate (n-channel case), providing a CP current which can be studied.When it was accepted that in submicron MOSFETs the CP current, Icp, was given by Icp = f.q.N, f being the gate signal frequency, q, the electron charge, and N, the number of traps entering Icp, recently, Tsuchiya and co-workers [2,3] studying devices having SiO2 obtained by Rapid Thermal Oxidation, pointed out step heights equal to 2.q among a number of steps from 0 to 2.q. Pb0 centers with their donor-like and acceptor-like states in the lower and upper halves of the silicon bandgap, respectively, were thus measured for the first time in such devices.As the energy at the interface that can be probed by CP is close to that between these two states, » 0.6 eV, the authors discussed the capability of CP to account for the two components with regard to the gate pulse characteristics.In the present paper, the traps remaining electrically active at the Si(100)-SiO2 interface in large area conventional MOSFETs after the full technological process including forming gas annealing are studied. This is achieved using techniques developed in recent years that use the variation of the gate signal frequency for different gate voltage swings [4]. Trap time constant distributions are pointed out and studied as function of gate voltage and gate signal frequency. The results are discussed with regard to those reported in [2,3], to the CP models previously proposed and to CP curves simulation [5].[1] G. Groeseneken et al. , IEEE Trans. Electron Devices 43, 940 (1996).[2] T. Tsuchiya and Y. Ono, Jap. J. Appl. Phys. 54, 04DC01 (2015).[3] T. Tsuchiya and P.M. Lenahan, Jap. J. Appl. Phys. 56, 031301 (2017).[4] Y. Manéglia, F. Rahmoune, and D. Bauza, J. Appl. Phys. 97, 014502 (2004).[5] D. Bauza, J. Appl. Phys. 94, 3239 2003).

Aspects of Relativistic Heavy-Ion Collisions

The rapid thermalization of quarks and gluons in the initial stages of relativistic heavy-ion collisions is treated using analytic solutions of a nonlinear diffusion equation with schematic initial conditions, and for gluons with boundary conditions at the singularity. On a similarly short time scale of t ≤ 1 fm/c, the stopping of baryons is accounted for through a QCD-inspired approach based on the parton distribution functions of valence quarks, and gluons. Charged-hadron production is considered phenomenologically using a linear relativistic diffusion model with two fragmentation sources, and a central gluonic source that rises with ln 3 ( s N N ) . The limiting-fragmentation conjecture that agrees with data at energies reached at the Relativistic Heavy-Ion Collider (RHIC) is found to be consistent with Large Hadron Collider (LHC) data for Pb-Pb at s N N = 2.76 and 5.02 TeV. Quarkonia are used as hard probes for the properties of the quark-gluon plasma (QGP) through a comparison of theoretical predictions with recent CMS, ALICE and LHCb data for Pb-Pb and p-Pb collisions.