This review paper discusses several key issues associated with deep submicron CMOS devices as well as advanced semiconductor materials in ionizing radiation environments. There are, as outlined in ...the ITRS roadmap, numerous challenges ahead for commercial industry in its effort to track Moore's Law down to the 45 nm node and beyond. While many of the classical threats posed by ionizing radiation exposure have diminished by aggressive semiconductor scaling, the question remains whether there may be unknown, potentially worse threats lurking in the deep submicron regime. This manuscript provides a basic overview of some of the materials, devices, and designs that are being explored or, in some cases, used today. An overview of radiation threats and how radiation effects can be characterized is also presented. Last, the paper provides a detailed discussion of what we know now about how modern devices and materials respond to radiation and how we may assess, through the use of advanced analysis and modeling techniques, the relative hardness of future technologies
In this letter, we propose a CMOS-compatible selector prototype based on a Cu-SiO 2 programmable metallization cell. With a porous e-beam evaporated SiO 2 switching layer, the filament ruptures in ...less than a millisecond. The device exhibits diode-like I-V characteristics with a selectivity of more than 10 7 . This volatile PMC can be changed to a bipolar resistive memory switch if the SiO 2 switching layer is thermally doped with Cu. Threshold switching is a result of filament dissolution caused by Cu diffusion in SiO 2 .
This paper presents a physics-based compact modeling approach that incorporates the impact of total ionizing dose (TID) and stress-induced defects into simulations of metal-oxide-semiconductor (MOS) ...devices and integrated circuits (ICs). This approach utilizes calculations of surface potential (ψ s ) to capture the charge contribution from oxide trapped charge and interface traps and to describe their impact on MOS electrostatics and device operating characteristics as a function of ionizing radiation exposure and aging effects. The modeling approach is demonstrated for bulk and silicon-on-insulator (SOI) MOS device. The formulation is verified using TCAD simulations and through the comparison of model calculations and experimental I - V characteristics from irradiated devices. The modeling approach is suitable for simulating TID and aging effects in advanced MOS devices and ICs, and is compatible with modern MOSFET compact modeling techniques. A circuit-level demonstration is given for TID and aging effects in SRAM cells.
The objectives, instrumentation, methods and data leading up to launch of the NASA Living With a Star (LWS) Space Environment Testbed (SET) payload onboard the Air Force Research Laboratory ...Demonstration and Science Experiments (DSX) spacecraft are described. The experiments characterize the space radiation environment and how it affects hardware performance. The payload consists of a compact space weather instrument and a carrier containing four board experiments.
•We examine resistance programming of programmable metallization cell memory devices.•Incremental resistance programming under electrical bias is experimentally observed.•Results indicate suitability ...of PMC devices for neuromorphic circuit applications.
In this work, we investigate the resistance switching behavior of Ag–Ge–Se based resistive memory (ReRAM) devices, otherwise known as programmable metallization cells (PMC). The devices studied are switched between high and low resistive states under externally applied electrical bias. The presence of multiple resistive states observed under both dc and pulse voltage application makes these devices promising candidates for use as electronic synapses in neuromorphic hardware implementations. Finally, the effect of varying pulse voltage magnitude and width on the change in resistance is observed through measurement.
A comprehensive model is presented which enables the effects of ionizing radiation on bulk CMOS devices and parasitic structures to be simulated with closed form functions. The model adapts general ...equations for defect formation in uniform SiO 2 films to facilitate analytical calculations of trapped charge and interface trap buildup in radiation sensitive shallow trench isolation (STI) oxides. An approach whereby defect distributions along the bottom and sidewall of the STI are calculated, incorporated into implicit surface potential equations, and ultimately used to model radiation-induced leakage currents in MOSFET structures and integrated circuits is described. The results of the modeling approach are compared to experimental data obtained on 130 and 90 nm devices and circuits. The features having the greatest impact on the increased radiation tolerance of advanced deep-submicron bulk CMOS technologies are also discussed. These features include increased doping levels along the STI sidewall.
Emerging nonvolatile memories (eNVMs) have demonstrated satisfactory accuracy on various applications in deep learning. Characterized by high density and low leakage power consumption, resistive ...random access memory (RRAM) becomes very attractive in synaptic devices for deep neural networks (DNNs). RRAM-based synaptic devices include both analog and discrete versions. Unlike analog RRAM synapses which suffer from nonlinearity, discrete but multistate RRAM synapses are better suited for neural network hardware implementation. In this article, the multistate operation in RRAM arrays has been proposed as a synaptic device for DNN inference. Four-state conductance has been achieved in HfO x -based RRAM synaptic arrays. The impact of total ionizing dose (TID) on the multistate behavior of HfO x -based RRAM is investigated by irradiating a one-transistor-one-resistor (1T1R) 64-kb array with CMOS peripheral decoding circuitry fabricated at the 90-nm technology node with Co-60 gamma rays ( 60 Co <inline-formula> <tex-math notation="LaTeX">\gamma </tex-math></inline-formula>-ray irradiation).
Summary Introduction Approximately 1% of the UK population take oral corticosteroids for ≥ 28 days each year, for broadly two reasons: deficiency in corticosteroid requiring replacement; or ...therapeutic corticosteroid for inflammatory conditions. Acute deficiency can occur at times of physiological stress (e.g. surgery), potentially leading to major complications. The Association of Anaesthetists' 2020 consensus guideline provides detailed advice for the management of glucocorticoids during the peri‐operative period for patients with adrenal insufficiency. This national audit aimed to assess compliance with this guideline. Methods Data were collected from 59 Trusts over 14 consecutive days for all eligible patients undergoing procedures under the care of an anaesthetist. Patients who were prescribed ≥ 5 mg oral prednisolone equivalents pre‐operatively, in whom supplementary corticosteroid would be indicated, were compared with those prescribed < 5 mg oral prednisolone equivalents. Results Operations for 21,731 patients were audited: 277 (1.3%) patients were taking therapeutic corticosteroids. Detailed peri‐operative data were collected for all patients receiving therapeutic corticosteroids: 201/277 (73%) were ASA physical status ≥ 3; 184/277 (66%) underwent elective procedures; and 252/277 (91%) were prescribed prednisolone pre‐operatively, of whom 219/277 (79%) were prescribed ≥ 5 mg oral prednisolone equivalents. In the patients who were prescribed ≥ 5 mg oral prednisolone equivalents, 186/219 (85%) received pre‐operative glucocorticoid supplementation and 97/219 (42%) received it postoperatively; however, only 67/219 (31%) and 43/219 (20%) respectively received glucocorticoid supplementation according to the guidelines. Overall, peri‐operative prescribing was compliant in 19/219 (9%) patients. A similar proportion, 30/219 (14%), received no supplementation. In the patients taking < 5 mg oral prednisolone equivalents pre‐operatively, 28/58 (48%) received inappropriate supplementation. Conclusions Despite 125/277 (45%) of anaesthetists reporting Association of Anaesthetists' guidelines use, compliance remained low, with adherence in only 27/125 (22%) patients. Further research is required to identify the correct peri‐operative strategy for patients taking therapeutic corticosteroids.
The changes caused by total ionizing dose (TID) in the conductance of the analog response of Ag-Ge30Se70 conductive bridge random access memory (CBRAM) based synapses are studied. The conductance was ...seen to be severely affected by 60Co gamma ray exposure. The devices were tested up to a TID of 1 Mrad(Ge30Se70). Scanning electron microscopy imaging supports the conclusion that the device degradation is due to loss of filament contact after irradiation. The effect of irradiation was further analyzed by simulating the devices in an artificial neural network. The training accuracy was seen to degrade from 85% to 15% with increasing TID levels.
•Study of thin film chalcogenide glasses under gamma radiation and a proposed radiation sensor design.•Structural changes were observed at various radiation doses.•Formation of Ag2Se in Se depleted ...glasses with sufficient radiation dose.•In conventional semiconductor chip environment, the proposed sensor has a linear current vs. dose behavior up to 600J/cm2.
Data about gamma radiation induced effects in Ge40Se60 chalcogenide thin films and radiation induced silver diffusion within these are presented. Blanket films and devices were created to study the structural changes, diffusion products, and device performance. Raman spectroscopy, X-ray diffraction, current vs. voltage (I–V) and impedance measurements expound the behavior of Ge40Se60 glass and silver diffusion within this glass under radiation. Raman study shows that there is a decrease in the area ratio between edge shared and corner shared structural units revealing structural reorganization occurring in the glasses as a result of gamma radiation. X-ray diffraction studies revealed that with sufficiently radiation dose it is also possible to create Ag2Se in selenium-depleted systems. Oxidation of the Ge enriched chalcogenide backbone is confirmed through the electrical performance of the sensing elements based on these films. Combination of these structural and diffusion products influences the device performance. The I–V behavior is characterized by increase in current and then stabilization as a function of radiation dose. Additionally, device modeling is also presented using Silvaco software and analytical methods to shed light on the device behavior. This type of sensor design and material characterizations facilitate in improving the radiation sensing capabilities of silver containing chalcogenide glass thin films.
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