Browsing by Author "Tan, Yung-Fang"

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A characteristic improved technique and analysis with plasma treatment to the electrode on oxide-based resistive random access memory
(2020-03-15)
Lin, Chih-Yang
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Chang, Ting-Chang
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Pan, Chih-Hung
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Chen, Min-Chen
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Xu, You-Lin
A technique was proposed to concentrate the distribution of set voltages. After a plasma treatment, the stability of the high-resistive state (HRS) increased, and the distribution of set voltages was more concentrated at 0.8 V, with a sufficient HRS/LRS resistive ratio (similar to 100x). In addition, the surface of the TiN electrode became rougher, causing oxygen to enter the TiN electrode and form a TiON layer, which acts as an oxygen reservoir. The reservoir is confirmed and the conduction model is supported by both electrical and material analyses. We propose that the observed improvement is due to the difference in the TiN electrode surface. (C) 2019 Published by Elsevier B.V.
Abnormal High Resistive State Current Mechanism Transformation in Ti/HfO2/TiN Resistive Random Access Memory
(2020-02-01)
Zhou, Kuan-Ju
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Chang, Ting-Chang
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Lin, Chih-Yang
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Chen, Chun-Kuei
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Tseng, Yi-Ting
In this letter, the electrical characteristics of Ti/HfO2/TiN resistive random access memory (RRAM) were thoroughly investigated. An abnormal current degradation was seen in the DC sweeping cycle. Both the on-state and off-state current clearly exhibited degradation with time. Next, current fitting analysis was used to investigate the carrier transport mechanisms. The results indicate that the on-state carrier transport mechanism changed from space-charge-limited current into hopping conduction after cycle sweeping. However, the off-state current changes from Schottky thermal emission to hopping conduction. Based on comparisons of different Schottky distances and Schottky barriers, physical models were proposed to explain the abnormal current degradation behavior. Finally, COMSOL electric field simulations were used to show the electric field distribution around the conducting filament (CF), and the conducting model was subsequently verified.
Impact of electrode thermal conductivity on high resistance state level in HfO2-based RRAM
(2020-09-23)
Lin, Shih-Kai
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Wu, Cheng-Hsien
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Chen, Min-Chen
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Chang, Ting-Chang
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Lien, Chen-Hsin
This study examines the influence of different electrode thermal conductivity on switching behavior during the reset process. Electrical analysis methods and an analysis of current conduction mechanism indicate that better thermal conductivity in the electrode will require larger input power in order to induce more active oxygen ions to take part in the reset process. More active oxygen ions result in a more oxidized switching layer, and cause the effective switching gap (d(sw)) to become larger in the reset process. The effect of the electrode thermal conductivity and input power are explained by our model and clarified by electrical analysis methods.
Improvement of Resistive Switching Characteristics in Zinc Oxide-Based Resistive Random Access Memory by Ammoniation Annealing
(2020-03-01)
Wu, Pei-Yu
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Zheng, Hao-Xuan
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Shih, Chih-Cheng
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Chang, Ting-Chang
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Chen, Wei-Jang
In this experiment, the electrical performance of zinc oxide based-resistive random access memory (RRAM) is successfully improved by using annealing in ammonia hydroxide solution at low-temperature and high pressure to complete ammonium-doped ZnO based-RRAM. The results of material analysis indicate that using CO2 as ammonia hydroxide carrier during the annealing process leads to the reduction in dangling bond density. This can be clearly observed in the decrease in breakdown voltage during the forming process and a lower operating current during operation. Furthermore, in this ammonium-doped ZnO based-RRAM, we study the molecular doping of NH3 in ZnO, where the endurance and retention properties are improved as well. These improvements can be attributed to the higher concentration of nitrogen in the switching layer, which can effectively control the active oxygen ions during the operation process.
Incorporation of Resistive Random Access Memory into Low-Temperature Polysilicon Transistor with Fin-Like Structure as 1T1R Device
(1970-01-01)
Huang, Wei-Chen
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Zheng, Hao-Xuan
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Chen, Po-Hsun
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Chang, Ting-Chang
;
Tan, Yung-Fang
In this study, a one transistor one resistor (1T1R) structure combining a fin-like low-temperature polycrystalline-silicon (LTPS) transistor and a resistive random access memory (RRAM) is successfully fabricated. For the fin-like LTPS transistor, both n-type and p-types show excellent electrical output characteristics. Fin-like structure produces more stable output characteristics. Also, the forming and current-voltage (I-V) characteristics are measured in this study, and the RRAM exhibits a forming voltage of about -1.9 V. As for the I-V switching property, the devices are stable and show excellent performance, with the set and reset voltages showing only minimal change over 100 cycles. Moreover, combining the fin-like LTPS transistor and RRAM into a 1T1R structure results in favorable operation over 100 cycles, with excellent retention and endurance. According to these results, RRAM can be successfully combined with a fin-like LTPS transistor for application in current integrated circuit processes without difficulty.
Investigation of the forming process under UV illumination in HfO2-based resistance random access memory with a transparent electrode
(2020-01-09)
Huang, Wei-Chen
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Huang, Shin-Ping
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Chen, Po-Hsun
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Chen, Min-Chen
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Chang, Ting-Chang
Traditionally, metal is used for the top electrode (TE) in HfO2-based resistance random access memory. When transparent indium-tin-oxide (ITO) is used as the TE, different forming processes, including lower forming voltages and higher forming currents, are exhibited. This work investigates the forming process with such a transparent TE under UV illumination. In addition, different TE thicknesses and device cell sizes are also investigated to confirm the results. Finally, a possible conduction model is provided to explain the mechanisms under UV-light illumination for the transparent TE during the forming process.
Overcoming Limited Resistance in 1T1R RRAM Caused by Pinch-Off Voltage During Reset Process
(2019-11-01)
Zheng, Hao-Xuan
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Chen, Min-Chen
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Chang, Ting-Chang
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Su, Yu-Ting
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Chen, Wen-Chung
This article explains the difference in the reset processes between single RRAM and 1T1R RRAM structures. In the single RRAM, as the reset voltage increases, the off-state resistance increases. This is a normal RRAM operation. However, in the 1T1R structure, the reset voltage increases while the OFF-state resistance does not increase. This may be caused by either current or voltage being insufficient to switch the RRAM to its higher resistance state. The measurements of real voltage indicate that the insufficient voltage is in fact the main cause. For the 1T1R RRAM structure, if it is to be reset to a higher resistance state, it is best done by increasing the gate voltage to increase the OFF-state resistance. Therefore, we provide a method to reduce the misjudgment in the array, and it would be beneficial for the development of high-density memory.
The influence of temperature on set voltage for different high resistance state in 1T1R devices
(2019-02-01)
Tan, Yung-Fang
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Su, Yu-Ting
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Chen, Min-Chen
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Chang, Ting-Chang
;
Tsai, Tsung-Ming
HfO2-based 1T1R is researched in this paper. The on-off ratio is an important electrical characteristic of RRAM, with a larger on-off ratio being preferable. However, temperature also affects the set process when operating RRAM. This study finds that the set process has different sensitivities to temperature at different high resistance states (HRSs). The set voltage of the higher HRS decreases with increasing temperature, while in the lower HRS, set voltage is independent of temperature. From the result, the lower HRS is better for RRAM because it is stable at different temperatures. (C) 2019 The Japan Society of Applied Physics