Browsing by Author "Jiang, Cheng-Min"

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Analytical Modeling of Read-Induced SET-State Conductance Change in a Hafnium-Oxide Resistive Switching Device
(2020-01-01)
Su, Po-Cheng
;
Jiang, Cheng-Min
;
Chen, Yu-Jia
;
Wang, Chih-Chieh
;
Li, Kai-Shin
A SET-state conductance change in a hafnium-oxide resistive switching memory cell due to repeated read events is investigated. We characterize a read-induced conductance change at different read voltages and SET-state conductance levels. Our result shows that the read-induced conductance degradation exhibits a two-stage evolution with the read pulse number. A SET-state conductance decreases slightly in the first stage and then follows inverse power-law dependence on the read number in the second stage. The power factor is an exponential function of a read voltage without regard to the SET-state conductance level, and the read pulse number at the transition of the two stages is related to a read voltage and conductance level. An analytical model to describe the two-stage conductance evolution is proposed. The parameters in the model are extracted from measurement data. Our model is verified by good agreement between the modeled and measured results in a wide range of read pulse number, read voltage, and SET-state conductance level.
Characterization of nitride hole lateral transport in a charge trap flash memory by using a random telegraph signal method
(2017-07-17)
Liu, Yu-Heng
;
Jiang, Cheng-Min
;
Lin, Hsiao-Yi
;
Wang, Tahui
;
Tsai, Wen-Jer
We use a random telegraph signal method to investigate nitride trapped hole lateral transport in a charge trap flash memory. The concept of this method is to utilize an interface oxide trap and its associated random telegraph signal as an internal probe to detect a local channel potential change resulting from nitride charge lateral movement. We apply different voltages to the drain of a memory cell and vary a bake temperature in retention to study the electric field and temperature dependence of hole lateral movement in a nitride. Thermal energy absorption by trapped holes in lateral transport is characterized. Mechanisms of hole lateral transport in retention are investigated. From the measured and modeled results, we find that thermally assisted trap-to-band tunneling is a major trapped hole emission mechanism in nitride hole lateral transport. Published by AIP Publishing.
Electric Field Induced Nitride Trapped Charge Lateral Migration in a SONOS Flash Memory
(2017-01)
Liu, Yu-Heng
;
Jiang, Cheng-Min
;
Chen, Wei-Chun
;
Wang, Tahui
;
Tsai, Wen-Jer
We investigated electric field-induced trapped electron lateralmigration in a SONOS flash cell. The threshold voltage shift (Delta V-t) andgate-induceddrain leakage(GIDL) current were measured to monitor nitride electron movement in retention. We applied different voltages to the gate and the source/drain in retention to vary the vertical and lateral electric fields. Our study shows that: 1) GIDL current can be used tomonitor trapped charge lateralmigration and 2) nitride charge lateral migration exhibits strong dependence on the lateral electric field. Based on measured temperature and field dependence, a nitride trapped charge emission process via thermally assisted tunneling is proposed for electron lateral migration. The emission rates of thermally assisted tunneling, direct trap-to-band tunneling and Frenkel-Poole emission were compared.
Electric Field Induced Nitride Trapped Charge Lateral Migration in a SONOS Flash Memory
(2017-01)
Liu, Yu-Heng
;
Jiang, Cheng-Min
;
Chen, Wei-Chun
;
Wang, Tahui
;
Tsai, Wen-Jer
We investigated electric field-induced trapped electron lateralmigration in a SONOS flash cell. The threshold voltage shift (Delta V-t) andgate-induceddrain leakage(GIDL) current were measured to monitor nitride electron movement in retention. We applied different voltages to the gate and the source/drain in retention to vary the vertical and lateral electric fields. Our study shows that: 1) GIDL current can be used tomonitor trapped charge lateralmigration and 2) nitride charge lateral migration exhibits strong dependence on the lateral electric field. Based on measured temperature and field dependence, a nitride trapped charge emission process via thermally assisted tunneling is proposed for electron lateral migration. The emission rates of thermally assisted tunneling, direct trap-to-band tunneling and Frenkel-Poole emission were compared.
Modeling of Read-Disturb-Induced SET-State Current Degradation in a Tungsten Oxide Resistive Switching Memory
(2018-11-01)
Su, Po-Cheng
;
Jiang, Cheng-Min
;
Wang, Chih-Wei
;
Wang, Tahui
;
電子工程學系及電子研究所
We characterize SET-state current degradation induced by read operations in a tungsten oxide resistive memory cell. The current degradation exhibits a two-stage evolution. In the second stage, the current decline follows inverse power-law dependence on cumulative read-disturb time. We present an analytical model to derive the inverse power law. Our model includes oxygen ion activation, mobile oxygen ion hopping, and the reduction of oxygen vacancy density by re-oxidation. Voltage and temperature effects on read-disturb-induced degradation are characterized for comparison with the model. Our results show that the power factor in the inverse power law has exponential dependence on a read voltage.