Browsing by Author "Chang, Ting-Chia"

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Bias Temperature Instabilities for High-kappa HfO2 LTPS-TFTs With Dual Plasma Treatment
(2016-03)
Wu, Chien-Hung
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Huang, Bo-Wen
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Chang, Kow-Ming
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Chang, Ting-Chia
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Wang, Shui-Jinn
This study is the first to investigate different reliability mechanisms of high-performance low-temperature polycrystalline silicon thin-film transistors (TFTs) with a HfO2 gate dielectric before and after dual plasma treatment (DPT) under various bias temperature instability (BTI) stresses. DPT samples under positive bias temperature instability (PBI) and negative bias temperature instability (NBI) stresses exhibited different degradation phenomena because of the negative polarity trapped oxide charges and positive fixed oxide charges (Si+), respectively. In addition, experimental data exhibited better reliability immunity for PBI stress than NBI stress after DPT. Furthermore, we raised the temperature to clearly observe the effect of the PBTI stress analysis for samples with and without DPT. Extracted measurement results showed distinct time evolutions of the interface state densities (Nit) for samples with and without DPT, revealing the different mechanisms of Nit generation with and without DPT. Finally, we proposed a novel reliability mechanism called the quasi reaction-diffusion model to explain the generation of Delta N-it, which also explains the unclear phenomena of mobility boost.
Electrical Improvement of MIS Capacitor with HfAlOx Gate Dielectrics Treated by Dual Plasma Treatment
(2012)
Deng, I-Chung
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Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
High dielectric constant materials (high-k) such as Hf-based thin films are the promising candidates for 45-nm CMOS technology. It has been described that nitridation processes could improve thermal stability and dielectric constants of Hf-based dielectrics. Furthermore, fluorine incorporation into high-k dielectric was also proposed in order to suppress leakage current and passivate defects. In this study, we examined dual plasma treatment (CF4 pretreatment and N-2 post-treatment) on HfAlOx thin films in order to improve electrical characteristics. Based on our experimental results, HfAlOx Metal-Insulator-Semiconductor (MIS) capacitor properties such as capacitance density, gate leakage current density, and hysteresis could be successfully improved. Compared to untreated samples, capacitance is 42.5% higher and gate leakage is suppressed about three orders when dual plasma treatment is used. According to this study, dual plasma treatment would be an effective technology to improve the electrical characteristic of HfAlOx thin films.
Improvement on Electrical Characteristics of HfO2 MIS Capacitor with Dual Plasma Treatment
(2011)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chen, Hshu-Wei
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電子工程學系及電子研究所
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Department of Electronics Engineering and Institute of Electronics
There have been some researches described that nitridation processes could improve thermal stability and dielectric constant of Hf-based dielectrics. The improvement of electrical characteristics of HfO2 thin films with plasma nitridation has been examined. Moreover, CF4 plasma treatment on HfO2 thin films in order to suppress leakage current and passivate defect were also proposed. In this study, we proposed to combine two kinds of plasma treatment, CF4 pre-treatment and nitrogen post-treatment, in order to have further improvement on electrical characteristics. The capacitance-voltage (C-V) characteristics, current-voltage (J-V) characteristics, and hysteresis of the samples were preformed to estimate the improvement effect. According to this study, dual plasma treatment would be an effective technology to improve the electrical characteristic and the hysteresis of pure HfO2 thin films.
Improvement on Interface Quality and Reliability Properties of HfAlOx MIS Capacitor with Dual Plasma Treatment
(2012)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chang, Po-Chun
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Huang, Bo-Wen
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Wu, Chien-Hung
HfO2 is considered a promising gate dielectric material for sub-45 nm CMOS technology. It has been reported that incorporate Al into HfO2 forming Hf aluminates in order to increase the crystallization temperature. However, the growth of the low-k interfacial layer at high-k/Si interface during high-k dielectric deposition would result in reliability degradation. Recently, incorporating nitrogen into HfAlOx gate dielectrics has beneficial effect on reliability performance. In addition, fluorine incorporation into high-k dielectrics also could have several improvements. In this study, dual plasma (CF4 pre-treatment and N-2 post-treatment) was performed on HfAlOx MIS capacitor in order to improve interface quality and the reliability properties. According to our experimental results, dual plasma treatment could improve interface quality and enhance reliability properties of HfAlOx thin films.
Machine Learning Hyperparameter Fine Tuning Service on Dynamic Cloud Resource Allocation System - taking Heart Sounds as an Example
(2018-01-01)
Peng, Yu-Hsiang
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Chuang, Chia-Chuan
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Wu, Zhou-Jin
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Chou, Chia-Wei
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Chen, Hui-Shan
The hyperparameters tuning of machine learning has always been a difficult and time-consuming task in deep learning area. In many practical applications, the hyperparameter tuning directly affects the accuracy. Therefore, the tuning optimization of hyperparameters is an important topic. At present, hyperparameters can only be set manually based on experience, and use Violent Enumeration, Random Search or through Grid Search to try and error, lack of effective automatic search parameters. In this study, we proposed a machine learning hyperparameter fine tuning service on dynamic cloud resource allocation system, which leverages several mainstream hyperparameter tuning methods such as flyperopt and Optunity. In the meanwhile, various tuning methods are measured and compared by example application in this work. Finally, we dedicated actual case - Heart Sounds, and then tested it. In order to verify that the system service can not only automate the task of tuning, but also break through the limitation of the number of adjustable parameters. Furthermore the proposed hyperparameter fine tune system makes optimization process more efficient.
Reliability Properties and Current Conduction Mechanisms of HfO2 MIS Capacitor with Dual Plasma Treatment
(2011)
Chang, Kow-Ming
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Chang, Ting-Chia
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Chen, Shou-Hsien
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Deng, I-Chung
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電機工程學系
The incorporation of nitrogen in HfO2 gate dielectrics has been reported to be beneficial for electrical performance. The improvement in the electrical characteristics of HfO2 thin film with plasma nitridation process or plasma fluorination process has also been examined. In this study, dual plasma, CF4 pre-treatment and nitrogen post-treatment, treatments were performed on HfO2 MIS capacitor for further improvement on reliability characteristic. We examine the reliability properties and the current conduction mechanism of HfO2 thin films. The frequency dispersion and constant voltage stress (CVS) characteristics of the samples were analyzed to estimate the improvement. According to the present study, dual plasma treatment could be better than single plasma treatment and would be an effective approach for HfO2 dielectric improvement.
Using dual plasma treatment to improve electrical characteristics and reduce flicker noise of high-kappa HfO2 LTPS-TFTs
(2015-09-01)
Chang, Kow-Ming
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Huang, Bo-Wen
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Wu, Chien-Hung
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Deng, I-Chung
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Chang, Ting-Chia
This study demonstrated the application of a dual plasma treatment to low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) comprising a self-aligned phosphorus implantation source and drain, high-kappa HfO2 gate dielectric, and aluminum metal gate. The dual plasma treatment involves a pre-deposition CF4 plasma treatment at a high-kappa/poly-Si interface and post-deposition N-2 plasma treatment at a high-kappa HfO2 gate dielectric; this treatment enables reducing the interface-trap-state defects at the high-kappa/poly-Si interface, grain boundary traps in the poly-Si channel film, and oxygen vacancy V-o in the high-kappa HfO2 gate dielectric. Thus, LTPS-TFTs with dual plasma treatment demonstrate excellent electrical characteristics such as threshold voltage, subthreshold swing, transconductance, driving current, and on/off current ratio. Flicker noise, also referred to as 1/f noise, caused by fluctuations of carriers transported in the grain boundary and the trapped carriers per unit oxide volume (N-t) can be suppressed. Therefore, high performance LTPS-TFTs subjected to dual plasma treatment can be appropriately applied to active matrix liquid phase-crystal display on system-on-panel technology. (C) 2015 Elsevier Ltd. All rights reserved.