Browsing by Author "Feng, Li-Wei"

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A study of resistive switching effects on a thin FeO(x) transition layer produced at the oxide/iron interface of TiN/SiO(2)/Fe-contented electrode structures
(2010-02-01)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Yao-Feng
;
Chen, Wei-Ren
;
Wang, Shin-Yuan
Large (>10(2)) and stable resistance switching characteristics were demonstrated in TiN/SiO(2)/Fe structure due to the presence of a thin FeO(x) transition layer at the SiO(2)/Fe interface, produced spontaneously during the plasma-enhanced tetraethyl orthosilicate oxide deposition process. Addition of Pt into Fe electrode, i.e., a TiN/SiO(2)/Fe(0.73)Pt(0.27) structure, was observed to improve the data dispersion of switching parameters, associating with the decrease in Fe content inside the FeO(x) layer. Additionally, current-voltage fitting data shows that current transport mechanism is governed by Ohm's law in low voltage region and Pool-Frenkel behavior in high voltage region, consisting with FeO(x) phase transition characteristics.
A study of resistive switching effects on a thin FeOx transition layer produced at the oxide/iron interface of TiN/SiO2/Fe-contented electrode structures
(2010-02-01)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Yao-Feng
;
Chen, Wei-Ren
;
Wang, Shin-Yuan
Large (>10(2)) and stable resistance switching characteristics were demonstrated in TiN/SiO2/Fe structure due to the presence of a thin FeOx transition layer at the SiO2/Fe interface, produced spontaneously during the plasma-enhanced tetraethyl orthosilicate oxide deposition process. Addition of Pt into Fe electrode, i.e., a TiN/SiO2/Fe0.73Pt0.27 structure, was observed to improve the data dispersion of switching parameters, associating with the decrease in Fe content inside the FeOx layer. Additionally, current-voltage fitting data shows that current transport mechanism is governed by Ohm's law in low voltage region and Pool-Frenkel behavior in high voltage region, consisting with FeOx phase transition characteristics.
Application of fluorine doped oxide (SiOF) spacers for improving reliability in low temperature polycrystalline thin film transistors
(2008-12-01)
Feng, Li-Wei
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Tu, Chun-Hao
;
Wu, Yung-Chun
The novel process of self-aligned fluorine doped oxide (SiOF) spacers on low temperature poly-Si (LTPS) lightly doped drain (LDD) thin film transistors (TFTs) is proposed. A fluorine doped oxide spacers were provided to generate the lower dissociation Si-F bonds adjusted to the interface of the drain which is the largest lateral electric field region for lightly doped drain structure. The stronger Si-F bonds can reduce the bonds broken by impact ionization. It is found that the output characteristics of SiOF spacers TFTs show the superior immunity to kink effect. The degradations in Vth shifting, subthreshold slope, drain current and transconductance of SiOF spacers after DC stress are improved. (C) 2008 Elsevier B.V. All rights reserved.
Degradation behaviors of trigate nanowires poly-si TFTs with NH3 plasma passivation under hot-carrier stress
(2007)
Wu, Yung-Chun
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Feng, Li-Wei
;
電子工程學系及電子研究所
This work studies degradation behavior after hot-carrier stress of trigate polysilicon thin-film transistors (poly-Si TFTs) with nanowires. The NH3 plasma passivation effect is also studied on the electrical characteristics after hot-carrier stress. The reliability of poly-Si TFTs with NH3 plasma passivation outperforms that without such passivation, resulting from the effective hydrogen passivation of the grain-boundary dangling bonds, and the pileup of nitrogen at the SiO2/poly-Si interface. The reliability of poly-Si TFTs further improves by using nanowires structure. These findings originate from the fact that the nanowires poly-Si TFT has robust trigate control to reduce the hot-carrier effect due to declining lateral electrical field and its penetration from the drain, and its split nanowire structure has superior NH3 plasma passivation effect. In degradation results under dc and ac stress, it reveals that the NH3 plasma is mostly passivated on deep traps of grain boundaries rather than tail traps.
Formation and composition of titanium oxinitride nanocrystals synthesized via nitridizing titanium oxide for nonvolatile memory applications
(2011-09-01)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
Formation and composition analyses of titanium oxinitride nanocrystals (NCs) fabricated via treating a magnetron co-sputtered thin film of titanium and silicon dioxide with a rapid thermal annealing in nitrogen ambient were demonstrated for nonvolatile memory applications. Phase separation characteristics with different annealing conditions were examined by transmission electron microscopy and chemical bonding characteristics were confirmed by X-ray photon emission spectra. It was observed that a blanket layer composed mainly of titanium oxide was still present as annealing temperature was increased to 700 degrees C, associated with the thermodynamically stable phase of titanium oxide. Furthermore, a higher thermal treatment of 900 degrees C induced formation of a well-separated NC structure and caused simultaneously partial nitridation of the titanium oxide, thereby forming titanium oxinitride NCs. A significant capacitance-voltage hysteresis in threshold voltage shift at 1 V was easily achieved under a small sweeping voltage range of + 2 V/-2 V, and a memory window retention of 2.2 V was obtained after 10(7) s by extrapolation under a 1 s initial-program/erase condition of +5 V/-5 V, respectively. (C) 2011 Elsevier B.V. All rights reserved.
Improved performance of F-ions-implanted poly-Si thin-film transistors using solid phase crystallization and excimer laser crystallization
(2007-03-01)
Tu, Chun-Hao
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Yang, Che-Yu
;
Feng, Li-Wei
Polycrystalline silicon thin-film transistors (Poly-Si TFTs) with F-ions-implantation were investigated in this study. The electrical characteristics and reliability of the F-ions-implanted poly-Si TFTs were reported for solid phase crystallization (SPC) and excimer laser crystallization (ELC) methods respectively. The thermal annealing causes F-ions to pile up at the poly-Si interface, without the initial pad oxide deposition. With the introduction of fluorine in poly-Si film, the trap state density was effectively reduced. Also, the presence of strong Si-F bonds enhances electrical endurance against hot carrier impact by using F-ions-implantation. These improvements in electrical characteristics are even obvious for the ELC poly-Si TFTs compared to the SPC ones.
Improvement of resistance switching characteristics in a thin FeO(x) transition layer of TiN/SiO(2)/FeO(x)/FePt structure by rapid annealing
(2010-05-31)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Yao-Feng
;
Chang, Ting-Chang
;
Wang, Shin-Yuan
In this paper, the influence of a 600 degrees C rapid thermal annealing for 60 s on the improvements of resistance switching behaviors in a TiN/SiO(2)/FeO(x)/FePt structure is reported. It is found that besides the distinct reduction in memory switching parameters in forming voltage, set/reset voltages, and their dispersions, the resistance ratio of high-resistance state to low-resistance state is also enlarged after annealing. The effects of annealing on improving the resistance switching properties are discussed by x-ray diffraction and x-ray photon-emission spectra depth profile results. Additionally, good retention characteristics are exhibited in the annealed TiN/SiO(2)/FeO(x)/FePt resistance switching memory. (C) 2010 American Institute of Physics. [doi:10.1063/1.3428777]
Improvement of resistance switching characteristics in a thin FeOx transition layer of TiN/SiO2/FeOx/FePt structure by rapid annealing
(2010-05-31)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Yao-Feng
;
Chang, Ting-Chang
;
Wang, Shin-Yuan
In this paper, the influence of a 600 degrees C rapid thermal annealing for 60 s on the improvements of resistance switching behaviors in a TiN/SiO2/FeOx/FePt structure is reported. It is found that besides the distinct reduction in memory switching parameters in forming voltage, set/reset voltages, and their dispersions, the resistance ratio of high-resistance state to low-resistance state is also enlarged after annealing. The effects of annealing on improving the resistance switching properties are discussed by x-ray diffraction and x-ray photon-emission spectra depth profile results. Additionally, good retention characteristics are exhibited in the annealed TiN/SiO2/FeOx/FePt resistance switching memory. (C) 2010 American Institute of Physics. [doi:10.1063/1.3428777]
Low temperature synthesis and electrical characterization of germanium doped Ti-based nanocrystals for nonvolatile memory
(2011-11-30)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
Chemical and electrical characteristics of Ti-based nanocrystals containing germanium, fabricated by annealing the co-sputtered thin film with titanium silicide and germanium targets, were demonstrated for low temperature applications of nonvolatile memory. Formation and composition characteristics of nanocrystals (NCs) at various annealing temperatures were examined by transmission electron microscopy and X-ray photon-emission spectroscopy, respectively. It was observed that the addition of germanium (Ge) significantly reduces the proposed thermal budget necessary for Ti-based NC formation due to the rise of morphological instability and agglomeration properties during annealing. NC structures formed after annealing at 500 degrees C, and separated well at 600 degrees C annealing. However, it was also observed that significant thermal desorption of Ge atoms occurs at 600 degrees C due to the sublimation of formatted GeO phase and results in a serious decrease of memory window. Therefore, an approach to effectively restrain Ge thermal desorption is proposed by encapsulating the Ti-based trapping layer with a thick silicon oxide layer before 600 degrees C annealing. The electrical characteristics of data retention in the sample with the 600 degrees C annealing exhibited better performance than the 500 C-annealed sample, a result associated with the better separation and better crystallization of the NC structures. (C) 2011 Elsevier B.V. All rights reserved.
Mechanism and characterizations studies of resistive switching effects on a thin FeO(x)-transition layer of the Ti/TiN/SiO(2)/FeO(x)/FePt structure by thermal annealing treatments
(2011-12-15)
Chang, Yao-Feng
;
Feng, Li-Wei
;
Chang, Ting-Chang
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We investigated annealing effects on the bipolar resistive switching characteristics and mechanism of the thin FeO(x) transition layer in a Ti/TiN/SiO(2)/FeO(x)/FePt structure by depositing a plasma-enhanced tetraethyl orthosilicate oxide onto the Fe-contented electrode. The electrical results show that the values of operation voltage, variation of electrical parameters and retention properties could be improved with the increasing thermal treatment budget. Tunneling electron microscope, X-ray diffraction, Auger electron spectroscopy and X-ray photon-emission spectra depth profiles were examined for cross-section image, crystallinity and composition analyses of the transition layer. In order to investigate the resistive switching mechanism and characterizations in Ti/TiN/SiO(2)/FeO(x)/FePt structure, the electrical parameters were extracted during set and reset process. The retention property at room temperature and 85 C was improved after the thermal treatment and maintains both resistance states over 6 x 10(4) s implies promising potential for future memory application. (C) 2011 Elsevier B.V. All rights reserved.
Mechanism and characterizations studies of resistive switching effects on a thin FeOx-transition layer of the Ti/TiN/SiO2/FeOx/FePt structure by thermal annealing treatments
(2011-12-15)
Chang, Yao-Feng
;
Feng, Li-Wei
;
Chang, Ting-Chang
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
We investigated annealing effects on the bipolar resistive switching characteristics and mechanism of the thin FeOx transition layer in a Ti/TiN/SiO2/FeOx/FePt structure by depositing a plasma-enhanced tetraethyl orthosilicate oxide onto the Fe-contented electrode. The electrical results show that the values of operation voltage, variation of electrical parameters and retention properties could be improved with the increasing thermal treatment budget. Tunneling electron microscope, X-ray diffraction, Auger electron spectroscopy and X-ray photon-emission spectra depth profiles were examined for cross-section image, crystallinity and composition analyses of the transition layer. In order to investigate the resistive switching mechanism and characterizations in Ti/TiN/SiO2/FeOx/FePt structure, the electrical parameters were extracted during set and reset process. The retention property at room temperature and 85 C was improved after the thermal treatment and maintains both resistance states over 6 x 10(4) s implies promising potential for future memory application. (C) 2011 Elsevier B.V. All rights reserved.
Nonvolatile Si/SiO2/SiN/SiO2/Si type polycrystalline silicon thin-film-transistor memory with nanowire channels for improvement of erasing characteristics
(2007-11-05)
Chen, Shih-Ching
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Chang, Ting-Chang
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Liu, Po-Tsun
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Wu, Yung-Chun
;
Chin, Jing-Yi
A silicon-oxide-nitride-oxide-silicon type polycrystalline silicon thin-film transistor (poly-Si TFT) with nanowire channels was investigated for both transistor and memory applications. The poly-Si TFT memory device has superior electrical characteristics, such as higher drain current, smaller threshold voltage, and steeper subthreshold slope. Also, the simulation result on electrical field reveals that the electrical field across the tunnel oxide is enhanced and that across the blocking oxide is reduced at the corner regions. This will lead to the parasitic gate injection activity and the erasing speed can be apparently improved in the memory device due to the pronounced corner effect and narrow channel width.
Performance enhancement of excimer laser crystallized poly-Si thin film transistors with fluorine implantation technology
(2008-03-31)
Tu, Chun-Hao
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Chang, Ting-Chang
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Liu, Po-Tsun
;
Yang, Che-Yu
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Feng, Li-Wei
Polycrystalline silicon thin film transistors (poly-Si TFTs) with the ion implantation of fluorine elements were investigated in this study. The electrical performance and reliability were reported comprehensively. Experimental work has shown the electrical characteristics of excimer laser crystallized F-ions-implanted poly-Si TFTs are improved effectively, especially for field effect mobility. It is also found that the fluorine piled up at the poly-Si interface during thermal annealing, for the TFT fabricated without a prior deposition of pad oxide. The stronger Si-F bonds replace the Si-Si/Si-H, leading to the superior electrical reliability. However, the dose of F ions is critical in poly-Si, or the electrical characteristics of TFT devices will be degraded. (c) 2007 Published by Elsevier B.V.
Pi-shape gate polycrystalline silicon thin-film transistor for nonvolatile memory applications
(2007-11-19)
Chen, Shih-Ching
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Chang, Ting-Chang
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Liu, Po-Tsun
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Wu, Yung-Chun
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Ko, Chin-Cheng
In this work, we studied a pi-shape gate polycrystalline silicon thin-film transistor (poly-Si TFT) with silicon-oxide-nitride-oxide-silicon (SONOS) layers and nanowire channels for the application of electric driver and nonvolatile memory. The proposed pi-gate TFT-SONOS has superior transfer characteristics and its output characteristic also exhibits the high driving current and the suppression of the kink effect. For memory application, the device can provide high program/erase efficiency and large threshold voltage shift under adequate bias operation. The enhanced performance for the pi-gate TFT-SONOS is attributed to the larger effective channel width and the number of channel corners. (C) American Institute of Physics.
Reliability Study on Tri-Gate Nanowires Poly-Si TFTs under DC and AC Hot-Carrier Stress
(2007)
Wu, Yung-Chun
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Chen, Hung-Bin
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Feng, Li-Wei
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Chang, Ting-Chang
;
Liu, Po-Tsun
This work studies reliability after dc and ac hot-carrier stress of polysilicon thin-film transistors (poly-Si TFTs) with single-channel and ten-nanowire channels, respectively. For single-channel (S1) poly-Si TFT, the device characteristics degradation under ac hot-carrier stress is severer than dc stress. In addition, the V-th and SS variation increases with the frequency increasing from 1 K Hz to 1 MHz. On the contrary, for tennanowire channels (M10) tri-gate poly-Si TFT, the V-th and SS variation is much lower than the S1 TFT with different stressing frequency. These results indicate that the M10 TFT has less deep state generation after dc and ac stress. Because the M10 TFT has more effective NH3 plasma passivation than that of S1 TFT due to the ten split nanowire channels has wide NH3 plasma passivation area. Moreover, M10 TFT has robust tri-gate control can reduce the lateral electrical field and its penetration from the drain to reduce hot-carrier effect. In ac stress study, the device degradation is dependent on the pulse failing time rather than rising time. In temperature study, the device degradation is improved as the operation temperature increasing from 25 degrees C to 75 degrees C.
Reproducible resistance switching of a relatively thin FeO(x) layer produced by oxidizing the surface of a FePt electrode in a metal-oxide-metal structure
(2010-12-30)
Feng, Li-Wei
;
Chang, Yao-Feng
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Wang, Shin-Yuan
In this study, reproducible resistance switching effects were demonstrated on a relatively thin FeO(x) layer in the TiN/SiO(2)/FeO(x)/FePt structure produced by oxidizing the surface of a FePt electrode during a plasma-enhanced tetraethyl orthosilicate oxide deposition process. Characteristics of the non-stoichiometric FeO(x) transition layer were examined by Auger electron spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. In addition, characteristics of the forming process as well as the current transport characteristics after forming process in the TiN/SiO(2)/FeO(x)/FePt structure were discussed. Moreover, the role of the silicon oxide layer was also experimentally demonstrated to act as an additional supplier of oxygen ions for the switching requirement by biasing high voltage bias conditions. (C) 2010 Elsevier B.V. All rights reserved.
Reproducible resistance switching of a relatively thin FeOx layer produced by oxidizing the surface of a FePt electrode in a metal-oxide-metal structure
(2010-12-30)
Feng, Li-Wei
;
Chang, Yao-Feng
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Wang, Shin-Yuan
In this study, reproducible resistance switching effects were demonstrated on a relatively thin FeOx layer in the TiN/SiO2/FeOx/FePt structure produced by oxidizing the surface of a FePt electrode during a plasma-enhanced tetraethyl orthosilicate oxide deposition process. Characteristics of the non-stoichiometric FeOx transition layer were examined by Auger electron spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy analyses. In addition, characteristics of the forming process as well as the current transport characteristics after forming process in the TiN/SiO2/FeOx/FePt structure were discussed. Moreover, the role of the silicon oxide layer was also experimentally demonstrated to act as an additional supplier of oxygen ions for the switching requirement by biasing high voltage bias conditions. (C) 2010 Elsevier B.V. All rights reserved.
Role of germanium in the reduced temperature dependence of Ti-based nanocrystals formation for nonvolatile memory applications
(2009-12-28)
Feng, Li-Wei
;
Chang, Chun-Yen
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Wang, Pai-Syuan
We investigated the physical and electrical characteristics of Ti-based nanocrystals (NCs) with composition of germanium fabricated by cosputtering titanium silicide and germanium targets for low temperature applications of nonvolatile memory. The addition of Ge significantly reduces the thermal budget necessary for Ti-based NCs formation to 500 degrees C in 2 min due to the rise of its morphological instability and agglomeration properties. Compositions characteristics were analyzed by x-ray photon-emission spectroscopy and formations of NCs were observed by transmission electron microscopy. Additionally, capacitance-voltage characteristics, data retention, and endurance properties are characterized to demonstrate its advantages for nonvolatile memory device applications.