Browsing by Author "Liu, Xi-Wen"

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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
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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)).
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
;
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
;
Chen, Ching-En
;
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
;
Chang, Ting-Chang
;
Liao, Jih-Chien
;
Chen, Li-Hui
;
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.
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
;
Yang, Ren-Ya
;
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.
The Impact of Pre/Post-metal Deposition Annealing on Negative-Bias-Temperature Instability in HfO2 Stack p-Channel Metal-Oxide-Semiconductor Field Effect Transistors
(2015-01-01)
Lu, Ying-Hsin
;
Chang, Ting-Chang
;
Ho, Szu-Han
;
Chen, Ching-En
;
Tsai, Jyun-Yu
This study investigates the impact of pre/post-metal deposition annealing on negative-bias-temperature instability (NBTI) in HfO2 stack p-channel metal-oxide-semiconductor field effect transistors (MOSFETs). In the initial electrical characteristics, the most apparent difference is threshold voltage (V-th) resulting from the work-function difference between the gate material and the semiconductor. Furthermore, fast I-V measurements indicate that the device with post-metal deposition annealing shows more degradation of V-th in NBTI, which originates from the more nitrogen interstitial defects in HfO2. This phenomenon is confirmed to be due to the process-related pre-existing defects by an analysis of double sweep fast I-V measurements. (c) 2015 The Electrochemical Society. All rights reserved.