Radiation damage effects in boron nitride mask membranes subjected to x-ray exposures

Johnson, W. A.

doi:10.1116/1.583878

Cited by 29 publications

(3 citation statements)

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“…1,2 The evaluation of mask materials usually involves the measurement of changes in optical transmission, which can affect alignment capabilities, and mechanical distortions, which will produce shifts in absorber positions to create overlay errors. The direct measurement of mask distortions is exposure geometry dependent and potentially time consuming.…”

Section: Introductionmentioning

confidence: 99%

Radiation damage-induced changes in silicon nitride membrane mechanical properties

Wells¹,

Chen²,

Wallace³

et al. 1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Traditional x-ray lithography mask radiation damage studies have concentrated on the pattern placement errors produced by stress changes within the mask membrane. The usual approach is to measure the location of fiducial marks on the mask membrane to measure the distortions for pre- and postirradiation. The measured distortions are not directly related to changes in individual mechanical properties of the membrane material. To isolate the individual mechanical parameters this study has utilized a silicon nitride membrane structure in the form of a bridge with lithographically patterned strain gauges to allow independent measurement of changes in the elastic modulus and Poisson’s ratio as a function of incident dose. It was found that the modulus of elasticity decreased by 37% for an incident dose of 114 kJ/cm2 while the Poisson ratio for the material remained unchanged within the accuracy of the experiment. The results of these measurements have been incorporated into a finite element model to numerically determine the resulting distortions and compare them with published experimental results.

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Section: Introductionmentioning

confidence: 99%

Radiation damage-induced changes in silicon nitride membrane mechanical properties

Wells¹,

Chen²,

Wallace³

et al. 1995

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…Typical materials developed for this purpose are boron-nitride (BN) (1,2), boron-nitro-carbide (BNC) (3,4), boron-doped silicon (Si) (5,6), silicon-nitride (SIN) (7,8), and silicon-carbide (SIC) (9,10). However, the boron compounds such as BN got out of use because of the low radiation durability (11)(12)(13). Up to these days, Si, SiN, and SiC have been widely used.…”

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confidence: 99%

Process Technologies for Ta / SiC X‐Ray Masks

Yamada

Kondo

Nakaishi

et al. 1990

J. Electrochem. Soc.

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This paper describes process technologies for an x-ray mask using Ta as the x-ray absorber and SiC as the x-ray membrane. SiC can be grown heteroepitaxially in a coldwall LPCVD reactor at 1000~ and 3.5 torr using a gas mixture of SiHC13, C3H8, and H2. SiC has a stress of 4 x 109 dyn/cm 2 and a Young's modulus of 4.7 x 10 '2 dyn/cm 2. Pure Ta with Ar ions implanted by 150 keV is more stable and dense than Ta alloys and their nitrides. The film density is about 16 g/cm 3 and the stress change due to annealing of 200~ is below 2 x 108 dyn/cm 2. The yield of stress control is 68% for 2 • l0 s dyn/cm 2. The temperature of the membrane during Ta RIE is controlled by He cooling from the back. It is held between 45 ~ and 100~ at a power density of 0.8 W/cm 2. A mixture of C12 and CC14 (1:1) is used as the etching gas. The gas pressure is from 0.18 to 0.2 torr. The etch rate of Ta is 1.2 ~tm/min and the selectivity of Ta to a resist (AMS-1) is 7. A 0.8 ~m thick Ta pattern of 0.15 ~m lines and spaces is obtained by using a 0.5 ~m thick single-layer resist. Electron beam lithography on a thin membrane requires a high-contrast resist (AMS-1) and a well-controlled correction of the proximity effect because of the high electron backscattering on Ta. Si etchback is done by spray etcher using a mixture of HF and HNO3 (1:3) with a high speed of 8 min per mask. The total fabrication process is designed to minimize mask distortion. The maximum mask distortion due to the absorber stress is 0.11 ~m (3~) including the measurement errors of Nikon 2I. The mask used for the measurement had a circular membrane of 60 mm diam and a 32 • 32 mm field window. The SiC was 2 ~m thick and the Ta was 0.8 ~m thick with a stress of 1.4 x 108 dyn/cm 2.It will be the key factor to establish a well-controlled and zero-defect x-ray mask for a successful application of x-ray lithography to deep submicron devices. The x-ray mask consists of some process technologies. Chemical vapor deposition (CVD), reactive ion etching (RIE), and electron beam delineation are the most common. The requirements for x-ray mask materials and processes are somewhat different from those of electronic devices.The x-ray membrane must have a tensile stress high enough to obtain flat surface and avoid vibration due to pressure difference on the two sides of the membrane. Especially, the mask vibration during the x-ray exposure and alignment process is a severe problem resulting in a loss of overlay accuracy and a loss of critical dimension (CD) control. A high stress above 1 x 109 dyn/cm 2 is preferable for this purpose. A high Young's modulus of membrane is

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“…When operating in such environments, the electronic devices may get struck by electrons, protons, neutrons or other heavier particles, thus altering their functionality/electrical properties and causing their failure. Another driving force for the active research in the area of radiation is the radiation damage caused by fabrication processing techniques such as electron-beam lithography [106,107], X-ray lithography [108], reactive ion etching [109]. In this regard, investigation of radiation effects in the semiconductor devices is of paramount importance for the development of the circuits that can operate properly in radiationrich environments.…”

Section: Ionizing Radiation On Mos Devicesmentioning

confidence: 99%

Sigma-Delta control of charge trapping in heterogeneous devices

Bheesayagari

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Dielectric charging represents a major reliability issue in a variety of semiconductor devices. The accumulation of charge in dielectric layers of a device often alters its performance, affecting its circuital features and even reducing its effective lifetime. Although several contributions have been made in order to mitigate the undesired effects of charge trapping on circuit performance, dielectric charge trapping still remains an open reliability issue in several applications. The research work underlying this Thesis mainly focuses on the design, analysis and experimental validation of control strategies to compensate dielectric charging in heterogeneous devices. These control methods are based on the application of specifically designed voltage waveforms that produce complementary effects on the charge dynamics. Using sigma-delta loops, these controls allow to set and maintain, within some limits, the net trapped charge in the dielectric to desired levels that can be changed with time. This allows mitigating long-term reliability issues such as capacitance-voltage (C-V) shifts in MOS and MIM capacitors. Additionally, the bit streams generated by the control loops provide real-time information on the evolution of the trapped charge. The proposed controls also allow compensating the effects of the charge trapping due to external disturbances such as radiation. This has been demonstrated experimentally with MOS capacitors subjected to various types of ionizing radiation (X-rays and gamma rays) while a charge control is being applied. This approach opens up the possibility of establishing techniques for active compensation of radiation-induced charge in MOS structures as well as a new strategy for radiation sensing. A modeling strategy to characterize the dynamics of the dielectric charge in MOS capacitors is also presented. The diffusive nature of the charge trapping phenomena allows their behavioral characterization using Diffusive Representation tools. The experiments carried out demonstrate a very good matching between the predictions of the model and the experimental results obtained. The time variations in the charge dynamics due to changes in the volatges applied and/or due to external disturbances have been also investigated and modeled. Moreover, the charge dynamics of MOS capacitors under sigma-delta control is analyzed using the tools of Sliding Mode Controllers for an infinite sampling frequency approximation. A phenomenological analytical model is obtained which allows to predict and analyze the sequence of control signals. This model has been successfully validated with experimental data. Finally, the above control strategies are extended to other devices such as eMIM capacitors and perovskite solar cells. Preliminary results including open loop and closed loop control experiments are presented. These results demonstrate that the application of the controls allows to set and stabilize both the C-V characteristic of an eMIM capacitor and the current-voltage characteristic (J-V) of a perovskite solar cell. La carga atrapada en dieléctricos suele implicar un problema importante de fiabilidad en muchos dispositivos semiconductores. La acumulación de dicha carga, normalmente provocada por las tensiones aplicadas durante el uso del dispositivo, suele alterar el rendimiento de éste con el tiempo, afectar sus prestaciones a nivel de circuital e, incluso, reducir su vida útil. Aunque durante años se han realizado muchos trabajos para mitigar sus efectos no deseados, sobre todo a nivel circuital, la carga atrapada en dieléctricos sigue siendo un problema abierto que frena la aplicabilidad práctica de algunos dispositivos. El trabajo de investigación realizado en esta Tesis se centra principalmente en el diseño, análisis y validación experimental de estrategias de control para compensar la carga atrapada en dieléctricos de diversos tipos de dispositivos, incluyendo condensadores MOS, condensadores MIM fabricados con nanotecnología y dispositivos basados en perovskitas. Los controles propuestos se basan en utilizar formas de onda de tensión, específicamente diseñadas, que producen efectos complementarios en la dinámica de la carga. Mediante el uso de lazos sigma-delta, estos controles permiten establecer y mantener, dentro de unos límites, la carga neta atrapada en el dieléctrico a valores prefijados, que pueden cambiarse con el tiempo. Esto permite mitigar problemas de fiabilidad a largo plazo como por ejemplo las derivas de la curva capacidad-tensión (C-V) en condensadores MOS y MIM. Adicionalmente, las tramas de bits generadas por los lazos de control proporcionan información en tiempo real sobre la evolución de la carga. Los controles propuestos permiten también compensar los efectos de la carga atrapada en dieléctricos debida a perturbaciones externas como la radiación. Esto se ha demostrado experimentalmente con condesadores MOS sometidos a diversos tipos de radiación ionizante (rayos X y gamma) mientras se les aplicaba un control de carga. Este resultado abre la posibilidad tanto de establecer técnicas de compensación activa de carga inducida por radiación en estructuras MOS, como una nueva estrategia de sensado de radiación. Se presenta también una estrategia de modelado para caracterizar la dinámica de la carga dieléctrica en condensadores MOS. La naturaleza difusiva de los fenómenos de captura y eliminación de carga en dieléctricos permite caracterizar dichos fenómenos empleando herramientas de Representación Difusiva. Los experimentos realizados demuestran una muy buena correspondencia entre las predicciones del modelo y los resultados experimentales obtenidos. Se muestra también como las variaciones temporales de los modelos son debidas a cambios en las formas de onda de actuación del dispositivo y/o a perturbaciones externas. Además, la dinámica de carga en condensadores MOS bajo control sigma-delta se analiza utilizando herramientas de control en modo deslizante (SMC), considerando la aproximación de frecuencia de muestreo infinita. Con ello se obtiene un modelo analítico simplificado que permite predecir y analizar con éxito la secuencia de señales de control. Este modelo se ha validado satisfactoriamente con datos experimentales. Finalmente, las estrategias de control anteriores se han extendido a otros dispositivos susceptibles de sufrir efectos de carga atrapada que pueden afectar su fiabilidad. Así, se han llevado a cabo experimentos preliminares cuyos resultados demuestran que la aplicación de controles de carga permite controlar y estabilizar la característica C-V de un condensador eMIM y la característica corriente-tensión (J-V) de una célula solar basada en perovskitas.

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Radiation damage effects in boron nitride mask membranes subjected to x-ray exposures

Cited by 29 publications

References 0 publications

Radiation damage-induced changes in silicon nitride membrane mechanical properties

Radiation damage-induced changes in silicon nitride membrane mechanical properties

Process Technologies for Ta / SiC X‐Ray Masks

Sigma-Delta control of charge trapping in heterogeneous devices

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