Browsing by Author "Liu, HW"

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A novel process to form cobalt silicided p(+) poly-Si gates by BF2+ implantation into bilayered CoSi/a-Si films and subsequent anneal
(1998-07-01)
Lai, WK
;
Liu, HW
;
Juang, MH
;
Chen, NC
;
Cheng, HC
A novel process that implants BF2+ ions into thin bilayered CoSi/a-Si films has been shown to form cobalt silicided pf poly-Si gates with excellent gate oxide integrity and very small flatband shift. The effects of not only using the CoSi layer as an implantation barrier but also keeping the a-Si underlayer during the initial silicide formation both significantly suppress the boron penetration through thin gate oxide.
Effects of CoSi2 on p(+) polysilicon gates fabricated by BF2+ implantation into CoSi amorphous Si bilayers
(1998-10-01)
Cheng, HC
;
Lai, WK
;
Liu, HW
;
Juang, MH
;
電子工程學系及電子研究所
The integrity of thin gate oxide structures fabricated by implanting BF2+ ions into bilayered CoSi/amorphous silicon films and subsequent annealing has been studied as a function of cobalt silicide thickness and implantation energy. Significant degradation of gate oxide integrity and flatband voltage shifts were found with increasing cobalt silicide thickness and annealing temperature. It is shown that although thinner cobalt silicide can result in excellent gate dielectric integrity it also leads to worse thermal stability at a high annealing temperature. Moreover, shallower implantation depth and lower annealing temperature can reduce the boron penetration, but depletion effects in polycrystalline silicon gates are caused accordingly. Hence, appropriate process conditions, involving trade-offs among CoSi2 thickness, implantation energy and annealing temperature, must be used to optimize the device performance while retaining the thin dielectric reliability.
Effects of rapid thermal annealing on cobalt silicided p(+) poly-Si gates fabricated by BF2+ implantation into bilayered CoSi/a-Si films
(1999-07-01)
Lai, WK
;
Liu, HW
;
Juang, MH
;
Cheng, HC
;
電子工程學系及電子研究所
The cobalt polycide gate formed by implanting BF2+ ions into the bilayered CoSi/a-Si films and the subsequent rapid thermal anneal has been studied. The resulting gate oxide integrity is characterized with respect to various silicide thicknesses and implantation energies. Significant degradation in gate oxide integrity and Aat-band voltage shift were found with increasing silicide thickness and annealing temperature, especially for the thicker CoSi2 films, which is attributable to severe boron penetration. Although a thinner silicide can achieve excellent gate dielectric reliability, it will lead to poor high-temperature thermal stability. Moreover, shallower implantation depth and lower annealing temperature, which sustain less boron penetration, would cause the poly-Si gate depletion effects. Therefore, appropriate conditions, which comprise the CoSi2 thickness, the implantation energy, and the annealing temperature, should be employed to optimize the device performance while retaining the thin dielectric reliability.
Effects of RCA clean-up procedures on the formation of roughened poly-Si electrodes for high-density DRAMs' capacitors
(1997-11-01)
Liu, HW
;
Lai, WK
;
Yu, SY
;
Huang, SC
;
Cheng, HC
A novel structure, the phosphorus-implanted poly-Si films treated with phosphoric acid (H3PO4) and cleaned by standard RCA cleanup procedures, has been demonstrated as the bottom electrodes of DRAMs' stacked capacitors. After the H3PO4 treatment and RCA cleaning process, micro-island structures are formed on the poly-Si surface of the storage electrodes, The NH4OH + H2O2 + H2O (SC-1) solution in the RCA cleaning procedures is the main component to change the porous surfaces and engraved structures, formed by H3PO4 treatment, into micro-islands. Although the electrical properties are slightly degraded compared to the control samples, but they fulfill the requirements of high-density DRAMs, resulting from the increment of cell capacitance. (C) 1997 Elsevier Science S.A.
Effects of RCA clean-up procedures on the formation of roughened poly-Si electrodes for high-density DRAMs' capacitors
(1997-11-01)
Liu, HW
;
Lai, WK
;
Yu, SY
;
Huang, SC
;
Cheng, HC
A novel structure, the phosphorus-implanted poly-Si films treated with phosphoric acid (H3PO4) and cleaned by standard RCA cleanup procedures, has been demonstrated as the bottom electrodes of DRAMs' stacked capacitors. After the H3PO4 treatment and RCA cleaning process, micro-island structures are formed on the poly-Si surface of the storage electrodes, The NH4OH + H2O2 + H2O (SC-1) solution in the RCA cleaning procedures is the main component to change the porous surfaces and engraved structures, formed by H3PO4 treatment, into micro-islands. Although the electrical properties are slightly degraded compared to the control samples, but they fulfill the requirements of high-density DRAMs, resulting from the increment of cell capacitance. (C) 1997 Elsevier Science S.A.
Enhanced phosphorescence and electroluminescence in triplet emitters by doping gold into cadmium selenide/zinc sulfide nanoparticles
(2005-10-01)
Liu, HW
;
Laskar, IR
;
Huang, CP
;
Cheng, JA
;
Cheng, SS
Gold-cadmium selenide/zinc sulfide (Au-CdSe/ZnS) nanocomposites (NCs) were synthesized and characterized by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) analysis, ultraviolet-visible (UV-visible) absorption and photoluminescence (PL) emission spectroscopy. The PL intensity in the Au-CdSe/ZnS NCs system was found to be much greater than that of CdSe/ZnS nanoparticles (NPs) alone, because of the surface-enhanced Raman scattering of An NPs. Adding Au-CdSe/ZnS NCs to the cyclometalated iridium(Ill) complex (Ir-complex) greatly enhanced the PL intensity of a triplet emitter. Three double-layered electroluminescence (EL) devices were fabricated where the emitting zone contains the definite mixture of Ir-complex and the NCs [molar concentration of Ir-complex/NCs = 1:0 (Blank, D-1), 1: 1 (D-2) and 1:3 (D-3)] and the device D-2 exhibited optimal EL performances. (c) 2005 Elsevier B.V. All rights reserved.
Excellent low-pressure-oxidized Si3N4 films on roughened poly-si for high-density DRAM's
(1998-09-01)
Liu, HW
;
Cheng, HC
;
電子工程學系及電子研究所
;
Department of Electronics Engineering and Institute of Electronics
High-reliability and good-performance stacked storage capacitors with high capacitance value of 17.8 fF/mu m(2) has been realized using low-pressure-oxidized thin nitride films deposited on roughened poly-Si electrodes. This novel electrodes are fabricated by H3PO4-etched and RCA-cleaned. The leakage current density at +2.5 and -2.5 V are 9.07 x 10(-9) and -2.4 x 10(-8) A/cm(2), respectively, fulfilling the requirements of 256 Mb DRAM's. Weibull plots of time-dependent-dielectric-breakdown (TDDB) characteristics under constant current stress and constant voltage stress also show tight distribution and good electrical properties. Hence, this easy and simple technique is promising for future high-density DRAM's applications.
Formation and properties of roughened poly-Si electrodes for high-density DRAMs
(1997)
Liu, HW
;
Lin, ZJ
;
Yu, SY
;
Huang, SC
;
Cheng, SC
A novel structure, based upon phosphorus-implanted poly-Si films treated with phosphoric acid (H3PO4) and the standard RCA cleaning process, has been demonstrated as the bottom electrodes of DRAMs(1) stacked capacitors. After the H3PO4 treatment and the RCA cleaning process, micro-islands are formed on the poly-Si surface of the electrodes. For the capacitors with this novel structure, the capacitance value is 18.17 fF/mu m(2) and the effective oxide thickness is 18.9 Angstrom in comparison with conventional capacitors of 5.77 fF/mu m(2) and 59.5 Angstrom. The roughened poly-Si electrode can achieve a surface enlargement of 3.15 times. The leakage current density at +1.65V and -1.65V are 7.24 x 10(-8) A/cm(2) and -3.31 x 10(-8) A/cm(2), respectively, fulfilling the requirements of 256Mb DRAMs. Weibull plots of time-zero-dielectric-breakdown (TZDB) characteristics under ramping voltage test also show tight distribution and good electrical properties. It indicates that the phosphorus-implanted poly-Si films etched by H3PO4 and then cleaned with the standard RCA process can easily and simply increase the surface area and have good electrical properties fulfilling the requirements of 256Mb DRAMs and beyond.
Observing enhanced phosphorescence and electroluminescence from triplet emitter by quantum dot doping
(2005)
Laskar, IR
;
Liu, HW
;
Huang, CP
;
Cheng, JA
;
Chen, TM
Luminescent CdSe/ZnS core-shell-type quantum dots (QDs) were synthesized by chemical colloidal methods. The photoluminescence (PL) intensity of a triplet emitter [bis(4-trifluoromethyl)-2-phenylbenzothiazolatoacetylacetonate-iridium(III) (Ir complex 1) and bis(4-methyl)-2-phenylbenzothiazolatoacetylacetonate-iridium(III) (Ir-complex 2)] was dramatically enhanced when bluish-green emitting CdSe/ZnS QDs were incorporated into these compounds. Experimental results indicate that the emissive region of QDs substantially overlaps with the low-energy absorption bands of Ir-complexes, indicating that the photons were absorbed by both the QDs and the Ir-complexes and that the energy absorbed by the QDs was transferred efficiently to the Ir-complex triplet emitter, resulting in the observed enhancement of PL intensity. A slow quenching of QDs emission was observed in a prepared set of solutions with gradual increasing of Ir complex concentration at a fixed QDs concentration in thin film PMMA matrix, which supports the energy transfer from Ir complex to QDs. In the fabricated double-layer electroluminescent (EL) devices, the emitting layer contained either only Ir-complex or a mixture of Ir-complex and CdSe/ZnS QDs with a specific molar ratio [Ir-complex/QDs = 1/0 (D-I); 1/0.5 (D-II),..., 1/10 (D-V)]. The EL intensity and the luminance efficiency for D-II were higher (luminescence yield = 19.3cd A(-1)) than those of the other devices. The PL and EL enhancement of the triplet emitter were also strongly supported by using ZnSe QDs rather than CdSe/ZnS QDs.
Observing enhanced phosphorescence and electroluminescence from triplet emitter by quantum dot doping
(2005-01-01)
Laskar, IR
;
Liu, HW
;
Huang, CP
;
Cheng, JA
;
Chen, TM
Luminescent CdSe/ZnS core-shell-type quantum dots (QDs) were synthesized by chemical colloidal methods. The photoluminescence (PL) intensity of a triplet emitter [bis(4-trifluoromethyl)-2-phenylbenzothiazolatoacetylacetonate-iridium(III) (Ir complex 1) and bis(4-methyl)-2-phenylbenzothiazolatoacetylacetonate-iridium(III) (Ir-complex 2)] was dramatically enhanced when bluish-green emitting CdSe/ZnS QDs were incorporated into these compounds. Experimental results indicate that the emissive region of QDs substantially overlaps with the low-energy absorption bands of Ir-complexes, indicating that the photons were absorbed by both the QDs and the Ir-complexes and that the energy absorbed by the QDs was transferred efficiently to the Ir-complex triplet emitter, resulting in the observed enhancement of PL intensity. A slow quenching of QDs emission was observed in a prepared set of solutions with gradual increasing of Ir complex concentration at a fixed QDs concentration in thin film PMMA matrix, which supports the energy transfer from Ir complex to QDs. In the fabricated double-layer electroluminescent (EL) devices, the emitting layer contained either only Ir-complex or a mixture of Ir-complex and CdSe/ZnS QDs with a specific molar ratio [Ir-complex/QDs = 1/0 (D-I); 1/0.5 (D-II),..., 1/10 (D-V)]. The EL intensity and the luminance efficiency for D-II were higher (luminescence yield = 19.3cd A(-1)) than those of the other devices. The PL and EL enhancement of the triplet emitter were also strongly supported by using ZnSe QDs rather than CdSe/ZnS QDs.
Plate-based biochemical assay using quantum dots as a fluorescent labeling agent
(2005-07-22)
Huang, CP
;
Liu, HW
;
Tsao, CY
;
Yin, LT
;
Chiu, SF
A biochemical assay based on fluorescence imaging analysis by confocal laser scanning as a detection technique is specified. The method involved a glass plate coated with nitrocellulose (NC), where alpha-human-IgE-biotin at various concentrations was immobilized on an NC plate. Luminescent core-shell CdSe/ZnS QD-SA conjugates were then used as a fluorescent labeling agent to be captured specifically by biotinated alpha-human-IgE immobilized in a micro-array by affinity binding between SA and biotin in a plate-based biochemical assay. A confocal laser scanner was used to detect the fluorescence signals from the alpha-human-IgE-biotin-SA-QD complex. Experimental findings reveal that fluorescence intensity of QD-SA saturated at QD concentrations above 0.4 mg/ml. Moreover, a calibration curve between the fluorescence intensity and the concentration of alpha-human-IgE-biotin is plotted. The range of detectable concentrations of biotinlated alpha-human IgE was found to be between 3.3 and 100 mu g/ml in the a-human-IgE-biotin-SA-QD complex. Therefore, the results were consistent with the binding specificity in a plate-based biochemical assay, as determined using luminescent QDs as a labeling agent. (c) 2004 Elsevier B.V. All rights reserved.
Plate-based biochemical assay using quantum dots as a fluorescent labeling agent
(2005-07-22)
Huang, CP
;
Liu, HW
;
Tsao, CY
;
Yin, LT
;
Chiu, SF
A biochemical assay based on fluorescence imaging analysis by confocal laser scanning as a detection technique is specified. The method involved a glass plate coated with nitrocellulose (NC), where alpha-human-IgE-biotin at various concentrations was immobilized on an NC plate. Luminescent core-shell CdSe/ZnS QD-SA conjugates were then used as a fluorescent labeling agent to be captured specifically by biotinated alpha-human-IgE immobilized in a micro-array by affinity binding between SA and biotin in a plate-based biochemical assay. A confocal laser scanner was used to detect the fluorescence signals from the alpha-human-IgE-biotin-SA-QD complex. Experimental findings reveal that fluorescence intensity of QD-SA saturated at QD concentrations above 0.4 mg/ml. Moreover, a calibration curve between the fluorescence intensity and the concentration of alpha-human-IgE-biotin is plotted. The range of detectable concentrations of biotinlated alpha-human IgE was found to be between 3.3 and 100 mu g/ml in the a-human-IgE-biotin-SA-QD complex. Therefore, the results were consistent with the binding specificity in a plate-based biochemical assay, as determined using luminescent QDs as a labeling agent. (c) 2004 Elsevier B.V. All rights reserved.
The oxidation mechanism of low-pressure dry oxidation of nitrides for memory devices
(1997-09-01)
Liu, HW
;
Su, HP
;
Lai, WK
;
Cheng, HC
;
電子工程學系及電子研究所
To be utilized in the high density dynamic random access memory devices, low-pressure dry oxidation of the very thin nitrides has been performed to successfully obtain the ultrathin capacitors' dielectrics with the effective oxide thickness (t(ox,eff)) of 30 - 60 Angstrom. For the electrical properties, the low-pressure dry oxidized (LPDO) nitrides express thinner effective oxide thickness, lower leakage current, and higher reliability than do the atmospheric pressure dry oxidized (APDO) nitrides. After analyzing the diluted HF etching profiles, Auger electron spectrum and Fourier transform infrared spectrum data, an oxide/nitride/oxide (O/N/O) structure is realized for the LPDO samples with respect to the nitride/oxide structure for the APDO ones. This ultrathin O/N/O structure is believed to be the main cause of improving the electrical characteristics. Finally, a low-pressure enhanced oxidation model is also proposed to explain the unusual oxidation phenomenon on the top of the nitride films. The mechanisms of APDO and atmospheric pressure wet oxidation of nitride films are also compared.
The oxidation mechanism of low-pressure dry oxidation of nitrides for memory devices
(1997-09-01)
Liu, HW
;
Su, HP
;
Lai, WK
;
Cheng, HC
;
電子工程學系及電子研究所
To be utilized in the high density dynamic random access memory devices, low-pressure dry oxidation of the very thin nitrides has been performed to successfully obtain the ultrathin capacitors' dielectrics with the effective oxide thickness (t(ox,eff)) of 30 - 60 Angstrom. For the electrical properties, the low-pressure dry oxidized (LPDO) nitrides express thinner effective oxide thickness, lower leakage current, and higher reliability than do the atmospheric pressure dry oxidized (APDO) nitrides. After analyzing the diluted HF etching profiles, Auger electron spectrum and Fourier transform infrared spectrum data, an oxide/nitride/oxide (O/N/O) structure is realized for the LPDO samples with respect to the nitride/oxide structure for the APDO ones. This ultrathin O/N/O structure is believed to be the main cause of improving the electrical characteristics. Finally, a low-pressure enhanced oxidation model is also proposed to explain the unusual oxidation phenomenon on the top of the nitride films. The mechanisms of APDO and atmospheric pressure wet oxidation of nitride films are also compared.