Browsing by Author "Dai, Chih-Hao"

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Abnormal interface state generation under positive bias stress in TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors
(2012-09-24)
Lo, Wen-Hung
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Chang, Ting-Chang
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Tsai, Jyun-Yu
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Dai, Chih-Hao
;
Chen, Ching-En
This Letter studies positive bias stress-induced abnormal interface state on TiN/HfO2 p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in V-th shift but without subthreshold slope degradation. However, charge pumping current (I-CP) shows a significant degradation after stress. Accordingly, the impact ionization-induced Nit located HfO2/SiO2 is proposed to demonstrate the ICP degradation. The AC stress with several frequencies is used to evidence the occurrence of impact ionization. Further, the device with additional pre-existing N-it located SiO2/Si has insignificant degradation due to reduction in stress electric field. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4752456]
Charge trapping induced drain-induced-barrier-lowering in HfO2/TiN p-channel metal-oxide-semiconductor-field-effect-transistors under hot carrier stress
(2012-04-09)
Lo, Wen-Hung
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Chang, Ting-Chang
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Tsai, Jyun-Yu
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Dai, Chih-Hao
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Chen, Ching-En
This letter studies the channel hot carrier stress (CHCS) behaviors on high dielectric constant insulator and metal gate HfO2/TiN p-channel metal-oxide-semiconductor field effect transistors. It can be found that the degradation is associated with electron trapping, resulting in G(m) decrease and positive Vth shift. However, Vth under saturation region shows an insignificant degradation during stress. To compare that, the CHC-induced electron trapping induced DIBL is proposed to demonstrate the different behavior of Vth between linear and saturation region. The devices with different channel length are used to evidence the trapping-induced DIBL behavior. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697644]
Charge trapping induced frequency-dependence degradation in n-MOSFETs with high-k/metal gate stacks
(2011-12-30)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
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Kuo, Yuan-Jui
;
Hung, Ya-Chi
This letter investigates the reliability issues of HfO(2)/Ti(1-x)N(x) metal-oxide-semiconductor field effect transistor in terms of static and dynamic stress. The results indicate threshold voltage (V(th)) instability under dynamic stress is more serious than that under static stress, owning to transient charge trapping within high-k dielectric. Capacitance-voltage techniques verified that electron trapping under dynamic stress was located in high-k dielectric near the source/drain (S/D) overlap region, rather than the overall dielectric. Furthermore, the V(th) shift clearly increases with an increase in dynamic stress operation frequency. This phenomenon can be attributed to the fact that electrons injecting to the S/D overlap region have insufficient time to de-trap from high-k dielectric. We further investigated the impact of different Ti(1-x)N(x) composition of metal-gate electrode on charge trapping characteristics, and observed that V(th) shift decreases significantly with an increase in the ratio of nitride. This is because the nitride atoms diffusing from the metal gate fill up oxygen vacancies and reduce the concentration of traps in high-k dielectric. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.
Enhanced gate-induced floating-body effect in PD SOI MOSFET under external mechanical strain
(2010-11-25)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
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Kuo, Yuan-Jui
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Chen, Shih-Ching
The influence of tensile mechanical strain on gate-induced floating-body effect (GIFBE) in advanced partially depleted SOI n-MOSFETs was investigated. Both drain current and mobility enhance after applying strain due to the reduction of average transfer effective mass. However, it was found that the GIFBE becomes serious under the mechanical strain. To explain this phenomenon, we first clarify the mechanism of GIFBE using different operation conditions. The experiment results indicate that the GIFBE can be attributed to the anode hole injection (AHI) rather than the widely accepted mechanism of electron band (EVB) tunneling. Based on the AHI model, the enhanced GIFBE under the mechanical strain is mainly due to the narrowing of band gap induced by the strain in the poly-gate. (C) 2010 Elsevier B.V. All rights reserved.
Hot carrier effect on gate-induced drain leakage current in high-k/metal gate n-channel metal-oxide-semiconductor field-effect transistors
(2011-07-04)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
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Kuo, Yuan-Jui
;
Ho, Szu-Han
This paper investigates the channel hot carrier stress (CHCS) effects on gate-induced drain leakage (GIDL) current in high-k/metal-gate n-type metal-oxide-semiconductor field effect transistors. It was found that the behavior of GIDL current during CHCS is dependent upon the interfacial layer (IL) oxide thickness of high-k/metal-gate stacks. For a thinner IL, the GIDL current gradually decreases during CHCS, a result contrary to that found in a device with thicker IL. Based on the variation of GIDL current at different stress conditions, the trap-assisted band-to-band hole injection model is proposed to explain the different behavior of GIDL current for different IL thicknesses. (C) 2011 American Institute of Physics. [doi:10.1063/1.3608241]
Hot Carrier Effect on Gate-Induced Drain Leakage Current in n-MOSFETs with HfO2/Ti1-xNx Gate Stacks
(2012)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
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Kuo, Yuan-Jui
;
Ho, Szu-Han
"This paper investigates the effect of channel hot carrier stress (CHCS) on gate-induced drain leakage (GIDL) current in n-type metal-oxide-semiconductor field effect transistor (n-MOSFETs) with HfO2/Ti1-xNx gate stacks. It was found that the behavior of GIDL current during CHCS has dependence with the interfacial layer (IL) oxide thickness of high-k/metal gate stacks. As IL thickness becomes thinner, the GIDL current has a gradual decrease during CHCS, which is contrary to the result of thick-oxide IL devices. Based on the variation of GIDL current (Delta I-GIDL) in different stress voltage across gate and drain terminals, trap-assisted band to band holes injection model was proposed to explain the different behavior of GIDL current for different IL thickness. Furthermore, we also investigated the impact of different Ti1-xNx composition of metal gate electrode on the Delta I-GIDL after CHCS, and observed that the magnitude of Delta I-GIDL decreases with the increase of nitride ratio. This is due to the fact that nitride atoms diffusing from the metal gate fill up oxygen vacancies, and reduce the concentration of traps in high-k dielectric. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.001206esl] All rights reserved."
Impact of Mechanical Strain on GIFBE in PD SOI p-MOSFETs as Indicated From NBTI Degradation
(2012-03-01)
Lo, Wen-hung
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Chang, Ting-Chang
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Dai, Chih-Hao
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Chung, Wan-Lin
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Chen, Ching-En
This letter investigates the impact of mechanical strain on gate-induced floating-body effect in partially depleted silicon-on-insulator p-channel metal-oxide-semiconductor field-effect transistors. The strained FB device has less NBTI degradation than unstrained devices. This behavior can be attributed to the fact that more electron accumulation induced by strain effect reduces the electric oxide field significantly during NBTI stress. Analysis of the body current (I-B) under source/drain grounded and floating operation indicates an increase in the anode electron injection and electron tunneling from conduction band which occur at the partial n(+) poly-Si gate and Si substrate, respectively. This phenomenon can be attributed to the bandgap narrowing which has been induced by the strain effect.
Impact of static and dynamic stress on threshold voltage instability in high-k/metal gate n-channel metal-oxide-semiconductor field-effect transistors
(2011-02-28)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
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Kuo, Yuan-Jui
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Lo, Wen-Hung
This letter investigates the impact of static and dynamic stress on threshold voltage (V(th)) instability in ultrathin n-channel metal-oxide-semiconductor field-effect transistors with hafnium-based gate stacks. Experimental results indicate V(th) shift under dynamic stress is more serious than that under static stress due to charge trapping within the high-k dielectric. Capacitance-voltage techniques demonstrated that electron trapping under dynamic stress was located in the high-k dielectric near the source/drain overlap region rather than throughout the overall dielectric layer. This implies in real circuit operation, the phenomenon of electrons trapped in high-k near the source/drain overlap is the main issue affecting V(th) instability. (C) 2011 American Institute of Physics. [doi:10.1063/1.3560463]
Impact of strain on gate-induced floating body effect for partially depleted silicon-on-insulator p-type metal-oxide-semiconductor-field-effect-transistors
(2013-01-15)
Lo, Wen-Hung
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Chang, Ting-Chang
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Dai, Chih-Hao
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Chung, Wan-Lin
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Chen, Ching-En
This work investigates impact of mechanical strain on gate-induced-floating-body-effect (GIFBE) for partially depleted silicon-on-insulator p-type metal-oxide-semiconductor field effect transistors (PD SOI p-MOSFETs). First part, the original mechanism of GIFBE on PD SOI p-MOSFETs is studied. The experimental results indicate that GIFBE causes a reduction in oxide electric field (E-ox), resulting in an underestimate of negative-bias temperature instability (NBTI) degradation. This can be attributed to the electrons tunneling from the process-induced partial n(+) poly gate and anode electron injection (AEI) model, rather than the electron valence band tunneling (EVB) widely accepted as the mechanism for n-MOSFETs. And then, the second part shows that the strained FB device has less NBTI degradation than the unstrained devices. This behavior can be attributed to the fact that more electron accumulation was induced by strain-induced band gap narrowing, reducing NBTI significantly. (c) 2012 Elsevier B.V. All rights reserved.
Investigation of Lateral Trap Position by Random Telegraph Signal Analysis in Moderate Inversion in n-Channel MOSFETs
(2013)
Chen, Ching-En
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Chang, Ting-Chang
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You, Bo
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Lo, Wen-Hung
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Ho, Szu-Han
This paper investigates the trap position by random telegraph signal (RTS) analysis in moderate inversion in partially depleted silicon-on-insulator n-channel metal-oxide-semiconductor field-effect transistors. In the diffusion current-dominated region, the electron concentration distribution is more non-uniform along the channel than the one in the drift current-dominated region. In the diffusion region, the application of drain (source) voltage can influence the potential at the drain (source) side only. Accordingly, the position of oxide trap can be further clarified using RTS measurements to compare both the capture times as well as the relative channel current amplitudes of devices with and without interchanged source/drain. (C) 2013 The Electrochemical Society. All rights reserved.
NBTI Degradation in LTPS TFTs Under Mechanical Tensile Strain
(2011-07-01)
Lin, Chia-Sheng
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Chen, Ying-Chung
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Chang, Ting-Chang
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Jian, Fu-Yen
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Hsu, Wei-Che
This letter investigates the negative-bias temperature instability (NBTI) degradation of p-channel low-temperature polycrystalline-silicon thin-film transistors (LTPS TFTs) under mechanical tensile stress. Experimental results reveal that the interface state density N(it) and grain boundary trap density N(trap) of tensile-strained LTPS TFTs are more pronounced than those of unstrained LTPS TFTs. Extracted density of states and conduction activation energy E(a) both show increases due to the strained Si-Si bonds, which implies that strained Si-Si bonds are able to react with dissociated H during NBTI stress. Therefore, NBTI degradation is more significant after tensile strain than in an unstrained condition.
On the Origin of Gate-Induced Floating-Body Effect in PD SOI p-MOSFETs
(2011-07-01)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, An-Kuo
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Kuo, Yuan-Jui
;
Jian, Fu-Yen
This letter systematically investigates the origin of gate-induced floating-body effect (GIFBE) in partially depleted silicon-on-insulator p-type MOSFETs. The experimental results indicate that GIFBE causes a reduction in the electrical oxide field, leading to an underestimate of negative-bias temperature instability degradation. This can be partially attributed to the electrons tunneling from the process-induced partial n(+) polygate. However, based on different operation conditions, we found that the dominant origin of electrons was strongly dependent on holes in the inversion layer under source/drain grounding. This suggests that the mechanism of GIFBE at higher voltages is dominated by the proposed anode electron injection model, rather than the electron valence band tunneling widely accepted as the mechanism for n-MOSFETs.
On the Origin of Hole Valence Band Injection on GIFBE in PD SOI n-MOSFETs
(2010-06-01)
Dai, Chih-Hao
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Chang, Ting-Chang
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Chu, Ann-Kuo
;
Kuo, Yuan-Jui
;
Chen, Shih-Ching
This letter systematically investigates the mechanism of gate-induced floating-body effect (GIFBE) in advanced partially depleted silicon-on-insulator metal-oxide-semiconductor field-effect transistors. Based on different operation conditions, we found that the hole current collected by the body terminal is strongly dependent on electrons in the inversion layer under a source/drain ground. This implies that GIFBE can be attributed to anode hole injection (AHI) rather than the widely accepted mechanism of electron valence band tunneling. Moreover, GIFBE was also analyzed as a function of temperature. The results provide further evidence that the accumulation of holes in the body results from the AHI-induced direct tunneling current from the gate.