| Summary: | 碩士 === 國立東華大學 === 電機工程學系 === 98 === Modern semiconductor nonvolatile memories, such as Flash memory, have been successfully scaled down to achieve large capacity memories through the improvements in photolithography technology. However, conventional memory scaling is expected to come up against technical and physical limits in the near future. In order to overcome this problem, many new materials have been proposed for next-generation memory application. Resistive random access memory (RRAM) has attracted great attention due to its potential for the replacement of flash memory in nonvolatile memory application. The RRAM device has the projected advantage of simple cell structure, fast programming, low power consumption, good endurance, long retention time, and nondestructive readout property. However, the resistive switching mechanism are still unclear up to now. The switching behaviors seem to different depending on the materials. The resistive switching effects were observed from various materials, such as perovskite oxides and transition metal oxides. In this thesis, the SrZrO3 (SZO)-based memory devices are applied in the RRAM devices, and the SZO memory films were deposited by rf magnetron sputter system from SZO powder target. The effects of different dopant concentration, different sputtering time, and different sputtering time on the resistive switching properties of the SZO-based memory devices are investigated.
In this thesis, chapter 1 shows the motivation and development of the memories. Chapter 2 introduces the memories, especially for the RRAM. The experimental details are indicated in chapter 3. Chapter 4 presents the electrical properties of the 0.3% V-doped SZO (V:SZO) resistive switching memory devices with LaNiO3 bottom electrode and Al top electrode, and the device structure shows bipolar resistive switching characteristics, which utilize the resistance change within the SZO film to store information via two different stable resistance states. We found that 0.3% V:SZO resistive-switching memory device has excellent endurance, retention time, and nondestructive readout property. The resistance ratio between high resistance state (HRS) and low resistance state (LRS) read still maintains 100 times at -2V after applying 50 voltage switching cycles. The retention time of the two states is over 104 seconds and the resistance ratio still keeps over 100 times. We would study the conduction mechanism of the 0.3% V:SZO resistive-switching devices, in order to understand the mechanism of resistive switching.
We have demonstrated that SZO devices with bistable resistive switching property , and with advantage including simple cell structure, long retention time, and nondestructive readout property. The SZO device is expected to be used as an alternative of flash memories embedded in logic circuits, and has attention for use as next-generation nonvolatile memories.
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