• JSTS:Journal of Semiconductor Technology and Science
• /
• v.13 no.2
• /
• pp.139-144
• /
• 2013

Negative bias temperature instability (NBTI) has become a major factor determining circuit reliability. The effect of the NBTI on the circuit performance depends on the duty cycle which represents the stress and recovery conditions of each device in a circuit. In this paper, we propose an analytical model to perform more accurate duty cycle estimation at the gate-level. The proposed model allows accurate (average error rate: 3%) computation of the duty cycle without the need for expensive transistor-level simulations Furthermore, our model estimates the waveforms at each node, allowing various aging effects to be applied for a reliable gate-level circuit aging analysis framework.

• Journal of the Korean Vacuum Society
• /
• v.13 no.4
• /
• pp.157-163
• /
• 2004

Dependence of residual compressive stress of diamond-like carbon (DLC) films on relative humidity was investigated. Polymeric, graphitic and diamond-like carbon films were prepared by r.f.-PACVD using methane or benzene with the negative self bias voltage of the substrate ranging from -100 to -800 V. In-situ measurements of the residual stress were carried out in an environment chamber where the relative humidity was varied from 10％ to 90％. In dense DLC film of high residual compressive stress and hardness, we could not observe any change in the residual compressive stress with relative humidity. However, in the cases of graphitic and polymeric DLC films, abrupt change in the residual stress occurred by changing the relative humidity. The quantity of the stress change was inversely proportional to the film thickness, which means that the stress change with humidity is not due to the penetration of the water molecule into the film structure, but due to surface interaction between water molecules and film surface.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.18 no.11
• /
• pp.996-1000
• /
• 2005

Experimental results are presented for the degradation of 3 nm-thick gate oxide $(SiO_2)$ under both Negative-bias Temperature Instability (NBTI) and Hot-carrier-induced (HCI) stresses using P and NMOSFETS, The devices are annealed with hydrogen or deuterium gas at high-pressure $(1\~5\;atm.)$ to introduce higher concentration in the gate oxide. Both interface trap and oxide bulk trap are found to dominate the reliability of gate oxide during electrical stress. The degradation mechanism depends on the condition of electrical stress that could change the location of damage area in the gate oxide. It was found the trap generation in the gate oxide film is mainly related to the breakage of Si-H bonds in the interface or the bulk area. We suggest that deuterium bonds in $SiO_2$ film are effective in suppressing the generation of traps related to the energetic hot carriers.

• JSTS:Journal of Semiconductor Technology and Science
• /
• v.3 no.2
• /
• pp.83-88
• /
• 2003

The reset operation of a CCD image sensor was improved using charge trapping of a MOS structure to realize a loe voltage driving. A DC bias generating circuit was added to the reset structure which sets reference voltage and holds the signal charge to be detected. The generated DC bias is added to the reset pulse to give an optimized voltage margin to the reset operation, and is controlled by adjustment of the threshold voltage of a MOS transistor in the circuit. By the pulse-type stress voltage applied to the gate, the electrons and holes were injected to the gate dielectrics, and the threshold voltage could be adjusted ranging from 0.2V to 5.5V, which is suitable for controlling the incomplete reset operation due to the process variation. The charges trapped in the silicon nitride lead to the positive and negative shift of the threshold voltage, and this phenomenon is explained by Poole-Frenkel conduction and Fowler-Nordheim conduction. A CCD image sensor with $492(H){\;}{\times}{\;}510(V)$ pixels adopting this structure showed complete reset operation with the driving voltage of 3.0V. The resolution chart taken with the image sensor shows no image flow to the illumination of 30 lux, even in the driving voltage of 3.0V.

• Healthcare Informatics Research
• /
• v.24 no.4
• /
• pp.381-386
• /
• 2018

Objectives: This study aimed to describe the process of utilizing a mobile application for ecological momentary assessment (EMA) to collect data on stress and mood in daily life setting. Methods: A mobile application for the Android operating system was developed and installed with a set of questions regarding momentary mood and stress into a smartphone of a participant. The application sets alarms at semi-random intervals in 60-minute blocks, four times a day for 7 days. After obtaining all momentary affect and stress, the questions to assess the usability of the mobile EMA application were also administered. Results: The data were collected from 97 police officers working in Gyeonggi Province of South Korea. The mean completion rate was 60.0% ranging from 3.5% to 100%. The means of positive and negative affect were 18.34 of 28 and 19.09 of 63. The mean stress was 17.92 of 40. Participants responded that the mobile application correctly measured their affect ($4.34{\pm}0.83$) and stress ($4.48{\pm}0.62$) of 5-point Likert scale. Conclusions: Our study investigated the process of utilizing a mobile application to assess momentary affect and stress at repeated times. We found challenges regarding adherence to the research protocol, such as completion and delay of answering after alarm notification. Despite this inherent issue of adherence to the research protocol, the EMA still has advantages of reducing recall bias and assessing the actual moment of interest at multiple time points that improves ecological validity.

• Journal of the Korean Vacuum Society
• /
• v.6 no.2
• /
• pp.151-158
• /
• 1997

Nitrogen incorporated diamond-like carbon films were deposited by r.f. glow discharge of mixtures of benzene and ammonia gases. Mechanical properties, composition and atomic bond structure were investigated when the fraction of ammonia increases from 0 to 0.79 and the negative self bias voltage of cathode from 100 to 900 V. Both the residual compressive stress and the hardness decrease from 1.7 to 1.0 GPa and from 2750Kgf/$\textrm{mm}^2$ to 1700Kgf/$\textrm{mm}^2$, respectively. In addition to hydrogen, triply bonded nitrogens also play a role of teminal sites of the three dimensional atomic bond network. By considering the hydrogen concentration and the nitrogen bond characteristics, it can be shown that the mechanical properties of the films are determined by the content of three dimensional inter-links of $sp^2$ clusters. Although the mechanical properties are affected by the nitrogen addition, its depedence on the negative bias voltage is qualitatively identical to that of pure diamond-like carbon films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.33 no.1
• /
• pp.6-9
• /
• 2020

Thin film transistors (TFTs) with large-area, high mobility, and high reliability are important factors for next-generation displays. In particular, thin transistors based on IGZO oxide semiconductors are being actively researched for this application. In this study, several methods for improving the reliability of a-IGZO TFTs by applying various materials on a passivation layer are investigated. In the literature, inorganic SiO₂, TiO₂, Al₂O₃, ZTSO, and organic CYTOP have been used for passivation. In the case of Al₂O₃, excellent stability is exhibited compared to the non-passivation TFT under the conditions of negative bias illumination stress (NBIS) for 3 wavelengths (R, G, B). When CYTOP passivation, SiO₂ passivation, and non-passivation devices were compared under the same positive bias temperature stress (PBTS), the Vth shifts were 2.8 V, 3.3 V, and 4.5 V, respectively. The Vth shifts of TiO₂ passivation and non-passivation devices under the same NBTS were -2.2 V and -3.8 V, respectively. It is expected that the presented results will form the basis for further research to improve the reliability of a-IGZO TFT.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.35 no.1A
• /
• pp.80-86
• /
• 2010

This work has been measured and analyzed the device degradation of NBTI (Negative Bias Temperature Instability) stress induced the increase of gate-induced-drain-leakage(GIDL) current for p-MOS transistors of gate channel length 0.13 [${\mu}m$]. From the relation between the variation of threshold voltage and subthreshold slop by NBTI stress, it has been found that the dominant mechanism for device degradation is the interface state generation. From the GIDL measurement results, we confined that the EHP generation in interface state due to NBTI stress led to the increase of GIDL current. As a results, one should take care of the increased GIDL current after NBTI stress in the ultra-thin gate oxide device. Also, the simultaneous consideration of reliability characteristics and dc device performance is highly necessary in the stress parameters of nanoscale CMOS communication circuit design.

• Transactions on Electrical and Electronic Materials
• /
• v.13 no.4
• /
• pp.188-191
• /
• 2012

This paper introduces a new method regarding deuterium incorporation in the gate dielectric including deuterium implantation and post-annealing at the back-end-of-the process line. The control device and the deuterium furnace-annealed device were also prepared for comparison with the implanted device. It was observed that deuterium implantation at a light dose of $1{\times}10^{12}-1{\times}10^{14}/cm^2$ at 30 keV reduced hot-carrier injection (HCI) degradation and negative bias temperature instability (NBTI) within our device structure due to the reduction in oxide charge and interface trap. Deuterium implantation provides a possible solution to enhance the bulk and interface reliabilities of the gate oxide under the electrical stress.

• Proceedings of the Safety Management and Science Conference
• /
• 2006.04a
• /
• pp.147-156
• /
• 2006

Since IMF system was introduced once, downsizing has been usual phenomenon in business sphere. Downsizing influences the unemployed, and also the survivors such as in job stress, communication bias, lower organizational commitment and so on. This paper reviewed the relationship between organizational commitment and service quality, and the moderating effect of sex in hotel. Based on the responses from 494 hotel employees, the results of multiple regressional analysis showed that affective OC and normative OC have affirmative effects on service quality. The results of moderating analysis showed that continuance OC has an affirmative interactive-effect on responsiveness, assurance, and empathy with gender, and affective OC an negative interactive-effect on assurance.