Resistive switching properties of sputtered ZrO2 thin films with Ti top electrode

• Main Authors: Tsai, Chen-Han, 蔡承翰
• Other Authors: 曾俊元
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/21990866743027682291

碩士 === 國立交通大學 === 電子工程系所 === 97 === Many kinds of consumer electrical commercial products are becoming more and more popular following with the development of the technology. All kinds of products need the memory, especially non-volatile memory, which can store data without power. The resistive switching random access memory (RRAM) is one of the next generational memories that have the chance to become the mainstream. It has the advantages of high cell density, high operation speed, low power consumption, high endurance, lower scale limit, non-destructive readout, and easy processing that can fit in the CMOS process, so it is one of the potential substitutions for flash memories. In this thesis, the resistive switching characteristics are investigated based on the Ti/ZrO2/Pt structure, and the research focus on two parts. First, the process temperature of ZrO2 is changed. Second, the thickness of ZrO2 and the area of the top electrode are changed. In the first part, the process temperature of the ZrO2 is changed to five temperatures: 25oC, 100 oC, 150 oC, 200 oC and 250 oC. The optimal value is 200 oC, so the following research of the mechanism will use this temperature. The performance of 200oC is good. DC sweep cycle times can achieve 10000 times; high speed 50ns pulse width can be switched at least 1000 cycle times; retention test is 106s; and there is no data loss at the nondestructive readout test for over 10000 seconds. In the second part, the purpose is to know the mechanism of the RRAM, so the structure is changed by various thicknesses of the ZrO2 and the various area of the top electrode. First, we can use the various thicknesses of the ZrO2 to find where the switching part in the filament is. Because Ti is a strong absorption metal, so there is an interface layer to be formed. The high yield, steady performance, and the polarities of the switching is related with the interface layer, and we can use the various thicknesses of ZrO2 to improve this mechanism. Second, the area of the top electrode is changed by the lithography. The resistance of the filament can be affected by this factor. At on-state, the current is not related with the area of the top electrode, but at off-state, the current is decreasing following the scale down of the top electrode. It is combined with the various thicknesses of ZrO2, so the mechanism of Ti-ZrO2-Pt is much clearer.