Browsing by Author "Tu, Chun-Hao"

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A fabrication of germanium nanocrystal embedded in silicon-oxygen-nitride layer
(2006)
Tu, Chun-Hao
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Chang, Ting-Chang
;
Liu, Po-Tsun
;
Liu, Hsin-Chou
;
Weng, Chi-Feng
The formation of germanium nanocrystals embedded in silicon-oxygen-nitride (SiON) layer acting as distributed charge storage elements is proposed in this work. A large memory window is observed due to the isolated Ge nanocrystals in the SiON gate stack layer. The Ge nanocrystals were nucleated after the high-temperature oxidation of SiGeN layer. The nonvolatile memory device with the Ge nanocrystals embedded in SiON stack layer exhibits 4 V threshold voltage shift under 7 V write operation. Also, the sequent high-temperature oxidation of the SiGeN layer acting as the blocking oxide is proposed to enhance the performance of nonvolatile memory devices. (c) 2006 The Electrochemical Society.
Application of fluorine doped oxide (SiOF) spacers for improving reliability in low temperature polycrystalline thin film transistors
(2008-12-01)
Feng, Li-Wei
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Chang, Ting-Chang
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Liu, Po-Tsun
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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.
Charge storage characteristics of high density Mo nanocrystal embedded in silicon oxide and silicon nitride
(2010-02-24)
Lin, Chao-Cheng
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Chang, Ting-Chang
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Tu, Chun-Hao
;
Chen, Shih-Ching
;
Hu, Chih-Wei
We investigated the formation and charge storage characteristics of Mo nanocrystals in silicon oxide and in silicon nitride by rapid thermal annealing of oxygen- and nitrogen-incorporated Mo and Si mixed layers. A high density of Mo nanocrystal (6 x 10(12) cm(-2)) was formed in the nitrogen-incorporated layer. Electrical analyses indicated that the memory window of the Mo nanocrystal embedded in the nitride is larger than that in the oxide. A reliability test showed that the Mo nanocrystal in the nitride has better reliability than the Mo nanocrystal in the oxide, which was explained by an electrical field simulation.
Charge storage characteristics of Mo nanocrystal dependence on Mo oxide reduction
(2008-12-01)
Lin, Chao-Cheng
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Chang, Ting-
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Tu, Chun-Hao
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Chen, Wei-Ren
;
Hu, Chih-Wei
An oxygen incorporated Mo silicide was explored to form the Mo nanocrystals after rapid thermal annealing. Transmission electron microscopy showed the nanocrystals embedded in SiO(x). Charge storage characteristics of Mo nanocrystals influenced by the Mo oxide and the surrounding oxide were investigated through x-ray photoelectron spectroscopy and the electrical measurement. X-ray photoelectron spectra analyses revealed the redox reaction in the oxygen incorporated Mo silicide layer after rapid thermal annealing. The memory window and retention were improved due to reduction in Mo oxide.
Charge Storage Characteristics of Mo Nanocrystal Memory Influenced by Ammonia Plasma Treatment
(2009)
Lin, Chao-Cheng
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Chang, Ting-Chang
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Tu, Chun-Hao
;
Chen, Wei-Ren
;
Hu, Chih-Wei
Mo nanocrystal memory was fabricated through annealing the oxygen-incorporated Mo and Si layers. We then investigated the influence an of ammonia plasma treatment on the nonvolatile memory characteristics of a charge storage layer composed of Mo nanocrystal memory embedded in SiO(x). Transmission electron microscopy revealed the nanostructure of the charge storage layer, and X-ray photoelectron spectra analyses revealed that nitrogen was incorporated into the charge storage layer. Electric analyses indicated that the memory window reduced, and both retention and endurance improved after the treatment. The reduction in the memory window was attributed to the decrease in charge trapping centers in the surrounding oxide after the treatment. The improvement of retention was interpreted in terms of the nitrogen passivation of traps in the oxide around the Mo nanocrystals. The robust endurance characteristic was attributed to the improvement of the quality of the surrounding oxide by nitrogen passivation.
Cobalt nanodots formed by annealing the CoSiO layer for the application of the nonvolatile memory
(2009-03-09)
Hu, Chih-Wei
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Chang, Ting-Chang
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Tu, Chun-Hao
;
Shueh, Pei-Kun
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Lin, Chao-Cheng
Co nanodot memory devices formed by oxidation processes were studied. Transmission electron microscopy and x-ray photoelectron spectroscopy analyses showed that overoxidation of the cobalt and silicon degraded the charge-storage ability seriously. However, a precapped oxide can mildly oxidize the CoSi(2) film to protect the overoxidation to occur. In addition, an oxygen-incorporated CoSi(2) film is proposed to improve the oxidation process further. Through incorporating the limited oxygen during sputtering process, the Co nanodot memory device obtains a larger memory window. Also, the reliability characteristic of the Co nanodot memory device formed by annealing the oxygen-incorporated CoSi(2) film has been demonstrated.
Electrical enhancement of solid phase crystallized poly-Si thin-film transistors with fluorine ion implantation
(2006)
Tu, Chun-Hao
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Chang, Ting- Chang
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Liu, Po-Tsun
;
Chen, Chih-Hung
;
Yang, Che-Yu
Solid phase recrystallized polycrystalline silicon thin-film transistors (SPC poly-Si TFTs) with fluorine ion implantation were investigated in this study. Electrical characteristics and reliability of the proposed poly-Si TFTs were improved effectively, especially for field effect mobility and off current. The fluorine-ion-implanted poly-Si TFT can suppress the hot carrier multiplication near the drain side, leading to superior endurance to electrical stress compared with conventional poly-Si TFTs. It was found that fluorine ions will pile up at the poly-Si interface during thermal annealing, without the initial deposition of pad oxide. The proposed technology is manageable and compatible with conventional poly-Si TFT fabrication. As the ion dosages increase more than 5x10(15) cm(-2), however, the electrical characteristics of poly-Si TFTs were degraded due to the increase of trap state density caused by the fluorine segregation in the poly-Si film.
Enhancement of NiSi-Based Nanocrystal Formation by Incorporating Ge Elements for Nonvolatile Memory Devices
(2009)
Hu, Chih-Wei
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Chang, Ting-Chang
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Tu, Chun-Hao
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Chiang, Cheng-Neng
;
Lin, Chao-Cheng
In this work, a NiSiGe mixed film was deposited by the cosputtering approach. The rapidly thermal treatment condition was executed at 600 degrees C for 30 s in nitrogen ambient to form the nanocrystal structure. From the results of the transmission electron microscopy, the annealed NiSiGe film reveals a larger nanocrystal size and density distribution than pure NiSi. X-ray photoelectron spectroscopy analyses were used to confirm that the Ge elements provide the additional nucleation centers and enhance the nanocrystal formation during the thermal process. Raman spectroscopy and an energy-dispersive spectrometer also exhibit the compositions of nanocrystals including Ni, Si, and Ge elements. With the better formation process, a remarkable improvement of memory effect is observed by comparing with the NiSi and NiSiGe nanocrystal memory devices. Also, the NiSiGe nanocrystal device shows a better retention characteristic due to the lower quantum confinement effect.
Formation and composition of titanium oxinitride nanocrystals synthesized via nitridizing titanium oxide for nonvolatile memory applications
(2011-09-01)
Feng, Li-Wei
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Chang, Chun-Yen
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Chang, Ting-Chang
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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.
Formation of cobalt-silicide nanocrystals in Ge-doped dielectric layer for the application on nonvolatile memory
(2008-04-14)
Hu, Chih-Wei
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Chang, Ting-Chang
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Liu, Po-Tsun
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Tu, Chun-Hao
;
Lee, Sheng-Kai
In this work, Ge-doped cobalt-silicon thin film was synthesized using a cosputter system (Co and Si(0.5)Ge(0.5)). The deposited film was annealed in oxygen ambient at 650 degrees C to form cobalt-silicide nanocrystals. The formation of isolated silicide nanocrystals was confirmed by transmission electron microscopy and x-ray photoelectron spectroscopy analysis. In metal-oxide-insulator-oxide-silicon structure, a significant electrical hysteresis is observed and attributed by the presence of the cobalt-silicide nanocrystals and the oxidized Ge elements. (C) 2008 American Institute of Physics.
Formation of germanium nanocrystals by rapid thermal oxidizing SiGeO layer for nonvolatile memory application
(2007-12-15)
Chen, Wei-Ren
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Chang, Ting-Chang
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Liu, Po-Tsun
;
Tu, Chun-Hao
;
Yeh, Jui-Lung
A new method to fabricate Ge nanocrystals by rapid thermal oxidizing SiGeO layer for nonvolatile memory application was investigated in this study. The oxidation process nucleated the Ge nanocrystals embedded in the dielectric layer was clearly observed by transmission electron microscope analysis. Moreover, an over-oxidation phenomenon for the formation of GeO2 in this work was found at higher temperature oxidation according to the X-ray photoelectron spectroscopy analysis. The obvious memory window was found in the capacitance-voltage hysteresis curve, and the program efficiency of holes was superior to electrons due to the electronic affinity of GeO2 smaller than silicon substrate for a structure of Ge nanocrystals surrounded with GeO2 layer. Furthermore, the Ge nanocrystals surrounded with GeO2 layer structure has good retention time and endurance. (c) 2007 Elsevier B.V All rights reserved.
Formation of germanium nanocrystals embedded in a silicon-oxygen-nitride layer
(2007)
Tu, Chun-Hao
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Weng, Chi-Feng
;
Liu, Hsin-Chou
The formation of germanium nanocrystals embedded in silicon-oxygen-nitride with distributed charge storage elements is proposed. A large memory window was observed due to isolated Ge nanocrystals in the SiON gate stack layer. The Ge nanocrystals were nucleated after a high-temperature oxidized SiGeN layer. The Ge nanocrystals embedded in the SiON stack layer exhibited nonvolatile memory characteristics with the obvious threshold voltage shift under a bidirectional voltage sweep. Also, the manufacturing technology using the sequent high-temperature oxidation of the a-Si layer and the direct oxidation of the SiGeN layer is proposed, respectively, for the formation of a blocking oxide layer to enhance the performance of nonvolatile memory devices. The reliability characteristics, including retention time and endurance, are also advisable for the application of nonvolatile memory device. (c) 2007 The Electrochemical Society.
Formation of germanium nanocrystals embedded in silicon-oxygen-nitride layer
(2006-07-31)
Tu, Chun-Hao
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Liu, Hsin-Chou
;
Tsai, Chia-Chou
The formation of germanium nanocrystals embedded in silicon-oxygen nitride with distributed charge storage elements is proposed in this work. A large memory window is observed due to isolated Ge nanocrystals in the SiON gate stack layer. The Ge nanocrystals were nucleated after high temperature oxidized SiGeN layer. The nonvolatile memory with the Ge nanocrystals embedded in SiON stack layer exhibits 4 V threshold voltage shift under 10 V write operation. Also, the manufacture technology using the sequent high-temperature oxidation of the a-Si layer acting as the blocking oxide is proposed to enhance the performance of nonvolatile memory devices. (c) 2006 American Institute of Physics.
Formation of Mo silicide nanodot memory by rapid thermal annealing dual electron-gun evaporated Mo-Si layer
(2008)
Lin, Chao-Cheng
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Chang, Ting-Chang
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Tu, Chun-Hao
;
Chen, Wei-Ren
;
Hu, Chih-Wei
In this study, distributed charge trapping centers molybdenum silicide nanodots, are demonstrated. The Mo silicide nanodots were formed in the rapid thermal annealed mixed Mo-Si layer deposited by a dual electron gun system. A significant memory effect is observed through the electrical measurements, which is attributed to the formation of Mo silicide nanodots. In addition, the memory window is large enough to be identified as logic level "0" and "1" for the application on nonvolatile memory. The manufacture processes are simple and compatible with the conventional semiconductor manufacturing processes. (C) 2008 The Electrochemical Society.
Formation of stacked Ni silicide nanocrystals for nonvolatile memory application
(2007-03-12)
Chen, Wei-Ren
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Chang, Ting-Chang
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Liu, Po-Tsun
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Lin, Po-Sun
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Tu, Chun-Hao
The formation of stacked Ni silicide nanocrystals by using a comixed target is proposed in this letter. High resolution transmission electron microscope analysis clearly shows the stacked nanocrystals embedded in the silicon oxide. The memory window enough to define "1" and "0" states is obviously observed at low voltage programming conditions, and good data retention characteristics are exhibited for the nonvolatile memory application. A physical model is also proposed further to explain the saturation phenomenon of threshold voltage at different programming voltages with operation duration. (c) 2007 American Institute of Physics.
Formation of the distributed NiSiGe nanocrystals nonvolatile memory formed by rapidly annealing in N(2) and O(2) ambient
(2010-10-01)
Hu, Chih-Wei
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Chang, Ting-Chang
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Tu, Chun-Hao
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Chiang, Cheng-Neng
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Lin, Chao-Cheng
In this work, electrical characteristics of the Ge-incorporated Nickel silicide (NiSiGe) nanocrystals memory device formed by the rapidly thermal annealing in N(2) and O(2) ambient have been studied. The trapping layer was deposited by co-sputtering the NiSi(2) and Ge, simultaneously. Transmission electron microscope results indicate that the NiSiGe nanocrystals were formed obviously in both the samples. The memory devices show obvious charge-storage ability under capacitance-voltage measurement. However, it is found that the NiSiGe nanocrystals device formed by annealing in N(2) ambient has smaller memory window and better retention characteristics than in O(2) ambient. Then, related material analyses were used to confirm that the oxidized Ge elements affect the charge-storage sites and the electrical performance of the NCs memory. (C) 2010 Elsevier B.V. All rights reserved.
Formation of the distributed NiSiGe nanocrystals nonvolatile memory formed by rapidly annealing in N-2 and O-2 ambient
(2010-10-01)
Hu, Chih-Wei
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Chiang, Cheng-Neng
;
Lin, Chao-Cheng
In this work, electrical characteristics of the Ge-incorporated Nickel silicide (NiSiGe) nanocrystals memory device formed by the rapidly thermal annealing in N-2 and O-2 ambient have been studied. The trapping layer was deposited by co-sputtering the NiSi2 and Ge, simultaneously. Transmission electron microscope results indicate that the NiSiGe nanocrystals were formed obviously in both the samples. The memory devices show obvious charge-storage ability under capacitance-voltage measurement. However, it is found that the NiSiGe nanocrystals device formed by annealing in N-2 ambient has smaller memory window and better retention characteristics than in O-2 ambient. Then, related material analyses were used to confirm that the oxidized Ge elements affect the charge-storage sites and the electrical performance of the NCs memory. (C) 2010 Elsevier B.V. All rights reserved.
Fort-nation of stacked nickel-silicide nanocrystals by using a co-mixed target for nonvolatile memory application
(2007-12-15)
Chen, Wei-Ren
;
Chang, Ting-Chang
;
Liu, Po-Tsun
;
Tu, Chun-Hao
;
Chi, Feng-Weng
The formation of stacked nickel-silicide nanocrystals by using a co-mixed target is proposed in this paper. High resolution transmission electron microscope analysis clearly shows the stacked nanocrystals embedded in the silicon oxide after rapid thermal oxidation. The obvious memory window can be used to define "1" and "0" states at low voltage operation. In addition, the program/erase characteristics have different charge/discharge efficiency due to the effect of stacked structure. Furthermore, good endurance and retention characteristics are exhibited for nonvolatile memory application. Besides, this technology is suitable for the fabrication of current nonvolatile memory and application of low power device. (C) 2007 Elsevier B.V. All rights reserved.
High Density Ni Nanocrystals Formed by Coevaporating Ni and SiO(2) Pellets for the Nonvolatile Memory Device Application
(2010-01-01)
Hu, Chih-Wei
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Chang, Ting-Chang
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Tu, Chun-Hao
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Huang, Yu-Hao
;
Lin, Chao-Cheng
We propose a method to fabricate a Ni nanocrystal structure by simultaneously coevaporating Ni and SiO(2) pellets. An 800 degrees C rapid thermal annealing was used to enhance the Ni nanocrystals to aggregate. Transmission electron microscopy indicates that the formed Ni nanocrystals show a high density distribution of about 4.5x10(12) cm(-2). Then, the memory device using the Ni nanocrystals as charge-trapping centers was fabricated. The Ni nanocrystal memory device has an obvious memory window under capacitance-voltage measurement. X-ray photoelectron spectroscopy confirms the memory effect results from the Ni nanocrystals embedded in the SiO(2) dielectric layer. Moreover, related reliability characteristics have been extracted.
High Density Ni Nanocrystals Formed by Coevaporating Ni and SiO2 Pellets for the Nonvolatile Memory Device Application
(2010-01-01)
Hu, Chih-Wei
;
Chang, Ting-Chang
;
Tu, Chun-Hao
;
Huang, Yu-Hao
;
Lin, Chao-Cheng
We propose a method to fabricate a Ni nanocrystal structure by simultaneously coevaporating Ni and SiO2 pellets. An 800 degrees C rapid thermal annealing was used to enhance the Ni nanocrystals to aggregate. Transmission electron microscopy indicates that the formed Ni nanocrystals show a high density distribution of about 4.5x10(12) cm(-2). Then, the memory device using the Ni nanocrystals as charge-trapping centers was fabricated. The Ni nanocrystal memory device has an obvious memory window under capacitance-voltage measurement. X-ray photoelectron spectroscopy confirms the memory effect results from the Ni nanocrystals embedded in the SiO2 dielectric layer. Moreover, related reliability characteristics have been extracted.