Browsing by Author "Liu, Hsi-Wen"

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Abnormal Transconductance Enhancement under Positive Bias Stress in Nanoscale n-Channel Fin Field-Effect-Transistors
(2016)
Liu, Kuan-Ju
;
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 abnormal transconductance in body-tied partially-depleted silicon-on-insulator n-MOSFETs
(2017-12-31)
Lin, Chien-Yu
;
Chang, Ting-Chang
;
Liu, Kuan-Ju
;
Chen, Li-Hui
;
Chen, Ching-En
This research investigates the mechanism of abnormal transconductance (Gm) and abnormal charge pumping current (I-CP) in body-tied partially-depleted silicon-on-insulator n-channel metal-oxide-semiconductor field effect transistors. The I-CP second hump region increases with channel length, yet is not affected by channel width. The cross-sectional view of the L-gate structure along the width direction demonstrates that a part of the poly gate area near the body contact is covered by a P+ implant, inducing a parasitic channel under the P+ poly gate. This parasitic channel leads to the abnormal Gm and I-CP hump, and such mechanism is further verified by body floating devices.
Analysis of Contrasting Degradation Behaviors in Channel and Drift Regions Under Hot Carrier Stress in PDSOI LD N-Channel MOSFETs
(2017-06-01)
Lin, Chien-Yu
;
Chang, Ting-Chang
;
Liu, Kuan-Ju
;
Chen, Li-Hui
;
Tsai, Jyun-Yu
This letter studies the effects of hot carrier stress (HCS) in laterally diffused silicon-on-insulator n-channel metal-oxide-semiconductor field-effect transistors. After HCS, threshold voltage and subthreshold swing degrade, while the ON-state current exhibits degradation after an abnormal spike due to hole trapping in the resistprotective oxide. Impact ionization simulation shows that low doping concentrations in the drift region cause a severe Kirk effect under HCS and more severe degradation at higher gate voltages. However, degradation in the channel contrasts with the simulation result, which suggests an additional mechanism. Variable temperature HCS confirms that channel degradation is instead dominated by temperature.
Combined Effects of Light Illumination and Various Bottom Gate Length on the Instability of Via-Contact-Type Amorphous InGaZnO Thin-Film Transistors
(2018-02-01)
Yang, Chung-I
;
Chang, Ting-Chang
;
Liao, Po-Yung
;
Chen, Bo-Wei
;
Chou, Wu-Ching
This paper utilizes electrical analyses and a study of physical mechanisms to investigate metal gate structure-dependent performance in amorphous InGaZnO (a-IGZO) thin-film transistors. The effects of different shielding areas between the IGZO layer and metal gate are investigated. In devices with shorter metal gate lengths, an abnormal rise in capacitance at the off-state in capacitance-voltage (C-V) characteristic curves can be observed. This can be attributed to the stronger electric field induced by the edge of the metal gate under bias sweep when the metal gate length is shorter than the IGZO layer length. Light illumination measurements indicate a negative shift in threshold voltage and an increase in subthreshold-leakage current regardless of relative metal gate length. Moreover, negative threshold voltage shift becomes more severe with a more obvious hump in C-V characteristic curves under back-light illumination of a shorter width device, a phenomenon which has been verified by simulation.
Impact of post-metal deposition annealing temperature on performance and reliability of high-K metal-gate n-FinFETs
(2016-12-01)
Lin, Chien-Yu
;
Chang, Ting-Chang
;
Liu, Kuan-Ju
;
Tsai, Jyun-Yu
;
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.
Trap state passivation improved hot-carrier instability by zirconium-doping in hafnium oxide in a nanoscale n-metal-oxide semiconductor-field effect transistors with high-k/metal gate
(2016-04-25)
Liu, Hsi-Wen
;
Chang, Ting-Chang
;
Tsai, Jyun-Yu
;
Chen, Ching-En
;
Liu, Kuan-Ju
This work investigates the effect on hot carrier degradation (HCD) of doping zirconium into the hafnium oxide high-k layer in the nanoscale high-k/metal gate n-channel metal-oxide-semiconductor field-effect-transistors. Previous n-metal-oxide semiconductor-field effect transistor studies demonstrated that zirconium-doped hafnium oxide reduces charge trapping and improves positive bias temperature instability. In this work, a clear reduction in HCD is observed with zirconium-doped hafnium oxide because channel hot electron (CHE) trapping in pre-existing high-k bulk defects is the main degradation mechanism. However, this reduced HCD became ineffective at ultra-low temperature, since CHE traps in the deeper bulk defects at ultra-low temperature, while zirconium-doping only passivates shallow bulk defects. Published by AIP Publishing.