Browsing by Author "Huang, Cheng-Tung"

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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
;
Chang, Ting-Chang
;
Tsai, Jyun-Yu
;
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]
Abnormal sub-threshold swing degradation under dynamic hot carrier stress in HfO2/TiN n-channel metal-oxide-semiconductor field-effect-transistors
(2013-07-08)
Tsai, Jyun-Yu
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Chang, Ting-Chang
;
Lo, Wen-Hung
;
Chen, Ching-En
;
Ho, Szu-Han
This work finds abnormal sub-threshold swing (S.S.) degradation under dynamic hot carrier stress (HCS) in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric. Results indicate that there is no change in S.S. after dynamic HCS due to band-to-band hot hole injection at the drain side which acts to diminish the stress field. Moreover, the impaired stress field causes the interface states to mainly distribute in shallow states. This results in ON state current and transconductance decreases, whereas S.S. degradation is insignificant after dynamic HCS. The proposed model is confirmed by one-side charge pumping measurement and gate-to-drain capacitance at varying frequencies. (C) 2013 AIP Publishing LLC.
Abnormal temperature-dependent floating-body effect on Hot-Carrier Degradation in PDSOI n-MOSFETs
(2014-12-01)
Liu, Kuan-Ju
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Chang, Ting-Chang
;
Yang, Ren-Ya
;
Chen, Ching-En
;
Ho, Szu-Han
This letter investigates abnormal degradation behavior after hot-carrier stress in partially-depleted silicon-oninsulator n-channel metal-oxide-semiconductor field effect transistors. It is found that the hot-carrier-induced degradation under floating body (FB) operation is more serious than that under grounded body (GB) operation due to the floating body effect (FBE). Furthermore, the degradation is independent on temperature under GB operation, because impact ionization is virtually independent on temperature under large VD. However, the degradation under FB operation becomes less serious with increasing temperature. This is due to a smaller source/body PN junction band offset at a high temperature, which causes fewer accumulated holes at the body terminal and reduces the FBE. (C) 2014 Elsevier B.V. All rights reserved.
Abnormal threshold voltage shift under hot carrier stress in Ti1-xNx/HfO2 p-channel metal-oxide-semiconductor field-effect transistors
(2013-09-28)
Tsai, Jyun-Yu
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Chang, Ting-Chang
;
Lo, Wen-Hung
;
Ho, Szu-Han
;
Chen, Ching-En
This work investigates the channel hot carrier (CHC) effect in HfO2/Ti1-xNx p-channel metal oxide semiconductor field effect transistors (p-MOSFETs). Generally, the subthreshold swing (S. S.) should increase during CHC stress (CHCS), since interface states will be generated near the drain side under high electric field due to drain voltage (V-d). However, our experimental data indicate that S. S. has no evident change under CHCS, but threshold voltage (V-th) shifts positively. This result can be attributed to hot carrier injected into high-k dielectric near the drain side. Meanwhile, it is surprising that such V-th degradation is not observed in the saturation region during stress. Therefore, drain-induced-barrier-lowering (DIBL) as a result of CHC-induced electron trapping is proposed to explain the different V-th behaviors in the linear and saturation regions. Additionally, the influence of different nitrogen concentrations in HfO2/Ti1-xNx p-MOSFETs on CHCS is also investigated in this work. Since nitrogen diffuses to SiO2/Si interface induced pre-N-it occurring to degrades channel mobility during the annealing process, a device with more nitrogen shows slightly less impact ionization, leading to insignificant charge trapping-induced DIBL behavior. (C) 2013 AIP Publishing LLC.
Abnormal Transconductance Enhancement under Positive Bias Stress in Nanoscale n-Channel Fin Field-Effect-Transistors
(2016)
Liu, Kuan-Ju
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Chang, Ting-Chang
;
Lin, Chien-Yu
;
Chen, Ching-En
;
Tsai, Jyun-Yu
This work demonstrates an abnormal transconductance (GM) enhancement after positive bias stress (PBS) in n-channel high-k/metal gate stacked fin-field-effect-transistors. This abnormal GM enhancement is observed only in short channel devices. With the speculation that hole-trapping-induced electron accumulation is the dominant mechanism, PBS with floating source and drain is adopted as an investigative approach. This, together with the electric field simulation, verifies that hole-trapping in the HfO2 and SiN near the gate corner induces electron accumulated at the ends of the channel length. Such a phenomenon results in a shortening of effective channel length and further GM enhancement. (C) 2016 The Electrochemical Society. All rights reserved.
Analysis of an anomalous hump in gate current after dynamic negative bias stress in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors
(1970-01-01)
Ho, Szu-Han
;
Chang, Ting-Chang
;
Wu, Chi-Wei
;
Lo, Wen-Hung
;
Chen, Ching-En
"This letter investigates a hump in gate current after dynamic negative bias stress (NBS) in HfxZr1-xO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. By measuring gate current under initial through body floating and source/drain floating, it shows that hole current flows from source/drain. The fitting of gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after dynamic NBS, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k epsilon(high-k) = Q + E-sio2 epsilon(sio2). (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4739525]"
Analysis of anomalous traps measured by charge pumping technique in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors
(2012-12-03)
Ho, Szu-Han
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Chang, Ting-Chang
;
Lu, Ying-shin
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Lo, Wen-Hung
;
Chen, Ching-En
This letter investigates anomalous traps measured by charge pumping technique in high voltage in HfO2/metal gate n-channel metal-oxide-semiconductor field-effect transistors. N-V-high level characteristic curves with different duty ratios indicate that the electron discharge time dominates the value of N for extra traps. By fitting ln (N (t(base level) = 2.5 mu s)-N (t(base level)))-Delta t(base level) at different temperatures and computing the equation t = tau(0) exp (alpha(e,SiO2)d(SiO2) + alpha(e,HfO2)d(HfO2,trap)), results show that these extra traps measured by the charge pumping technique at high voltage can be attributed to high-k bulk shallow traps. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4769444]
Analysis of Oxide Trap Characteristics by Random Telegraph Signals in nMOSFETs With HfO2-Based Gate Dielectrics
(2016-04)
Chen, Ching-En
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Chang, Ting-Chang
;
You, Bo
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Tsai, Jyun-Yu
;
Lo, Wen-Hung
This letter investigates the oxide trap properties in n-channel metal-oxide-semiconductor field-effect transistors with HfO2 and Hf(1-x)ZrxO(2)/metal gate-stacks by an analysis of random telegraph signals. According to the multiphonon emission theory, the extracted relaxation energies show gate voltage dependence in devices with HfO2-based stacks. This dependence results from the different strengths of vibrations of the nearest neighbor Hf atoms of the oxygen vacancy in the immediate vicinity of the oxide trap. Furthermore, this dependence also induces an abnormal gate voltage dependence in terms of the activation energy required for electron capture. These results are confirmed by comparisons between two HfO2-based devices (HfO2 and Hf(1-x)ZrxO(2)).
Anomalous Gate Current Hump after Dynamic Negative Bias Stress and Negative-Bias Temperature-Instability in p-MOSFETs with HfxZr1-xO2 and HfO2/Metal Gate Stacks
(2013)
Ho, Szu-Han
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Chang, Ting-Chang
;
Wu, Chi-Wei
;
Lo, Wen-Hung
;
Chen, Ching-En
In this study, the authors investigated an anomalous gate current hump after dynamic negative bias stress (NBS) and negative-bias temperature-instability (NBTI) in HfxZr1-xO2 and HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. This result is attributed to hole trapping in high-k bulk. Measuring gate current under initial through body floating and source/drain floating conditions indicates that holes flow from source/drain to gate. The fitting of the gate current-gate voltage characteristic curve demonstrates that Frenkel-Poole mechanism dominates the conduction under initial. Next, fitting the gate current after dynamic NBS and NBTI indicates Frenkel-Poole then tunneling mechanisms, finally returning to the Frenkel-Poole mechanism. These phenomena can be attributed to hole trapping in high-k bulk and the formula Ehigh-k epsilon(high-k) = Q + E-sio2 epsilon(sio2). To further understand the gate current hump, both Zr-undoped and 8 similar to 10% Zr-doped in high-k bulk devices were used for comparisons. These results indicate that initial gate current is also a significant factor in generating the anomalous gate current hump, and all results obey the hump generation condition of J(Tunneling) << J(Frenkel-Poole). (C) 2013 The Electrochemical Society. All rights reserved.
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]
Effects of fabrication method on defects induced by nitrogen diffusion to the hafnium oxide layer in metal-oxide-semiconductor field effect transistors
(2016-12-01)
Lu, Ying-Hsin
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Chang, Ting-Chang
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Ho, Szu-Han
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Chen, Ching-En
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Tsai, Jyun-Yu
This study investigates how different metal gate fabrication methods induce variations in the defects which result from nitrogen diffusing into the hafnium oxide layer in metal-oxide-semiconductor field effect transistors (MOSFETs). By using the different fabrication methods of pre-TaN, post-TaN and post-TiN annealing, the work-function difference between the gate material and the semiconductor can be adjusted, leading to apparent differences in threshold voltage (V-th). In addition, the results of slow and fast I-V NBTI measurements show that the amount of the bulk trapping in the post-TiN device is the highest, followed by the post-TaN device and then the pre-TaN device. In addition, a nitrogen interstitial defect phenomenon, resulting in a temporary shift of threshold voltage (V-th) which is highest in the post-TiN the lowest in the pre-TaN device, is determined by double sweep fast I-V measurements. (C) 2016 Elsevier B.V. All rights reserved.
Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks
(2014-10-06)
Tsai, Jyun-Yu
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Chang, Ting-Chang
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Chen, Ching-En
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Ho, Szu-Han
;
Liu, Kuan-Ju
This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO2 interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks. (C) 2014 AIP Publishing LLC.
Fast-IV Measurement Investigation of the Role of TiN Gate Nitrogen Concentration on Bulk Traps in HfO2 Layer in p-MOSFETs
(2017-06-01)
Lu, Ying-Hsin
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Chang, Ting-Chang
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Liao, Jih-Chien
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Chen, Li-Hui
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Lin, Yu-Shan
This letter investigates the role of the TiN gate's nitrogen concentration on bulk traps in the HfO2 layer in p-MOSFETs using fast I-V measurement. During negative bias temperature instability, the holes trapped in the HfO2 layer will induce Vth degradation. The fast I-V double sweep confirms the holes are trapped in process-related pre-existing defects. These defects are interstitial-type, influenced by the nitrogen in the TiN gate diffusing to the HfO2 layer when the device undergoes thermal annealing. Moreover, these nitrogen interstitials increase with increasing TiN gate nitrogen concentration, which induces more holes being trapped in the HfO2 layer.
High-k shallow traps observed by charge pumping with varying discharging times
(2013-11-07)
Ho, Szu-Han
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Chang, Ting-Chang
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Lu, Ying-Hsin
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Wang, Bin-Wei
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Lo, Wen-Hung
In this paper, we investigate the influence of falling time and base level time on high-k bulk shallow traps measured by charge pumping technique in n-channel metal-oxide-semiconductor field-effect transistors with HfO2/metal gate stacks. N-T-V-high level characteristic curves with different duty ratios indicate that the electron detrapping time dominates the value of N-T for extra contribution of I-cp traps. N-T is the number of traps, and I-cp is charge pumping current. By fitting discharge formula at different temperatures, the results show that extra contribution of I-cp traps at high voltage are in fact high-k bulk shallow traps. This is also verified through a comparison of different interlayer thicknesses and different TixN1-x metal gate concentrations. Next, N-T-V-high level characteristic curves with different falling times (t(falling time)) and base level times (t(base level)) show that extra contribution of I-cp traps decrease with an increase in t(falling time). By fitting discharge formula for different t(falling time), the results show that electrons trapped in high-k bulk shallow traps first discharge to the channel and then to source and drain during t(falling time). This current cannot be measured by the charge pumping technique. Subsequent measurements of N-T by charge pumping technique at t(base level) reveal a remainder of electrons trapped in high-k bulk shallow traps. (c) 2013 AIP Publishing LLC.
Hole injection-reduced hot carrier degradation in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric
(2013-02-18)
Tsai, Jyun-Yu
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Chang, Ting-Chang
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Lo, Wen-Hung
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Chen, Ching-En
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Ho, Szu-Han
This work finds a significant difference in degradation under hot carrier stress (HCS) due to additional hole injection in n-channel metal-oxide-semiconductor field-effect-transistors with high-k gate dielectric. A comparison performed on degradation of input/output (I/O) and standard performance (SP) devices showed that performance degradation of the I/O device is worse than the SP device under HCS. For the SP device, both channel-electrons and hot holes can inject into gate dielectric, in which hole acts to diminish the stress field. However, I/O device shows only electron injection. The proposed model is confirmed by gate induced drain leakage current and simulation tool. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4791676]
Impact of post-metal deposition annealing temperature on performance and reliability of high-K metal-gate n-FinFETs
(2016-12-01)
Lin, Chien-Yu
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Chang, Ting-Chang
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Liu, Kuan-Ju
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Tsai, Jyun-Yu
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Chen, Ching-En
This research studies the effects of post-metal deposition annealing temperature on degradation induced by positive bias stress (PBS) in TiN/HfO2 n-channel fin field-effect transistors (FinFETs). The initial electrical characteristics possess higher threshold voltage, transconductance and on-state current in high-annealing temperature devices. In addition, PBS-induced degradation was found to be more severe in high-annealing temperature devices due to more high-k bulk traps. However, in these devices, oxygen vacancies are generated within HfO2 since oxygen is more likely to diffuse toward the interface layer (IL) and repair Si/SiO2 dangling bonds. Furthermore, using charge-pumping and C-V measurements, less interface trapping and a thicker IL were found in high-annealing temperature devices, verifying the proposed model. (C) 2016 Elsevier B.V. All rights reserved.
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 abnormal negative threshold voltage shift under positive bias stress in input/output n-channel metal-oxide-semiconductor field-effect transistors with TiN/HfO2 structure using fast I-V measurement
(2014-03-17)
Ho, Szu-Han
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Chang, Ting-Chang
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Lu, Ying-Hsin
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Chen, Ching-En
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Tsai, Jyun-Yu
This letter investigates abnormal negative threshold voltage shifts under positive bias stress in input/output (I/O) TiN/HfO2 n-channel metal-oxide-semiconductor field-effect transistors using fast I-V measurement. This phenomenon is attributed to a reversible charge/discharge effect in pre-existing bulk traps. Moreover, in standard performance devices, threshold-voltage (V-t) shifts positively during fast I-V double sweep measurement. However, in I/O devices, V-t shifts negatively since electrons escape from bulk traps to metal gate rather than channel electrons injecting to bulk traps. Consequently, decreasing pre-existing bulk traps in I/O devices, which can be achieved by adopting HfxZr1-xO2 as gate oxide, can reduce the charge/discharge effect. (C) 2014 AIP Publishing LLC.
Investigation of an anomalous hump in gate current after negative-bias temperature-instability in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors
(2013-01-07)
Ho, Szu-Han
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Chang, Ting-Chang
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Wu, Chi-Wei
;
Lo, Wen-Hung
;
Chen, Ching-En
This Letter investigates a hump in gate current after negative-bias temperature-instability (NBTI) in HfO2/metal gate p-channel metal-oxide-semiconductor field-effect transistors. Measuring gate current at initial through body floating and source/drain floating shows that hole current flows from source/drain. The fitting of gate current (I-g)-gate voltage (V-g) characteristic curves demonstrates that the Frenkel-Poole mechanism dominates the conduction. Next, by fitting the gate current after NBTI, in the order of Frenkel-Poole then tunneling, the Frenkel-Poole mechanism can be confirmed. These phenomena can be attributed to hole trapping in high-k bulk and the electric field formula Ehigh-k epsilon(high-k) = Q+E-sio2 epsilon(sio2). (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4773479]
Investigation of defect-induced abnormal body current in fin field-effect-transistors
(2015-08-24)
Liu, Kuan-Ju
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Chang, Ting-Chang
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Chen, Ching-En
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Yang, Ren-Ya
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Tsai, Jyun-Yu
This letter investigates the mechanism of abnormal body current at the linear region in n-channel high-k/metal gate stack fin field effect transistors. Unlike body current, which is generated by impact ionization at high drain voltages, abnormal body current was found to increase with decreasing drain voltages. Notably, the unusual body leakage only occurs in three-dimensional structure devices. Based on measurements under different operation conditions, the abnormal body current can be attributed to fin surface defect-induced leakage current, and the mechanism is electron tunneling to the fin via the defects, resulting in holes left at the body terminal. (C) 2015 AIP Publishing LLC.