Fabrication and Investigation of InxGa1-xO Insulator for Non-volatile RRAM

  • 林 永哲

Student thesis: Doctoral Thesis

Abstract

Fabrication and Investigation of InxGa1-xO Insulator for Non-volatile RRAM Yong-Zhe Lin* Shoou-Jinn Chang** Institute of Microelectronic & Department of Electrical Engineering National Cheng Kung University Abstract In this thesis InxGa1-xO is used as the resistive switching layer of non-volatile random-access memory This is because indium atoms and gallium atoms are always used as the materials of transistors sensors and solar cells and electrical property can be modulated by changing the ratio of indium atoms to gallium atoms First Pt Ti and Al are used as the top electrode and Pt is used as bottom electrode We investigated the manufacturing process and electrical property of the RRAM devices Because the three top electrodes has different chemical properties transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDS) are used to analyze the interface of the top electrode and the resistive switching layer and confirm the impact of the top electrode on the electrical properties Moreover we research Pt/InxGa1-xO/Pt RRAM Ti/InxGa1-xO/Pt RRAM and Al/InxGa1-xO/Pt RRAM and investigate the impact of the In/Ga ratio on the electrical properties of the RRAM devices As the results demonstrate at room temperature the fabricated devices can switch over 100 times and maintain high resistance state (HRS) and low resistance state (LRS) for 10000 seconds respectively in the bipolar switching mode with 100mV reading voltage Then Al/Ga2O3/Pt RRAM is improved specially because its best performance among all the devices The oxygen vacancies are diminished by increasing the oxygen partial pressure of RF sputtering system As the results demonstrate the resistive switching performance will be better if the oxygen vacancies are diminished appropriately At room temperature the Al/Ga2O3/Pt RRAM device can switch over 2000 times and maintain high resistance state and low resistance state for 10000 seconds respectively in the bipolar switching mode with 100mV reading voltage Finally we use Al as the top electrode Pt as the bottom electrode and from the bottom electrode to the top electrode Ga2O3 In0 1Ga0 9O In0 4Ga0 6O In0 9Ga0 1O and In2O3 as the resistive switching layer to fabricate the penta-layer gradual binary oxide RRAM (Gradual RRAM) We find that the resistive switching performance is improved due to the gradient of the mobility and concentration gradient of the oxygen vacancies It means that not only the electrode and the material of the resistive switching layer have impact on the performance of RRAM but also the structure of gradual binary oxide is one of the methods to improve the performance of RRAM Key words: non-volatile RRAM InxGa1-xO In2O3 Ga2O3 Author* Advisors**
Date of Award2019
Original languageEnglish
SupervisorShoou-Jinn Chang (Supervisor)

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