| 摘要: | 本論文將鐵電電晶體(FeMFET)操作於 1.5V 至 4V，研究不同鐵電參數對於非揮發性鐵電電晶體記憶體之讀取電流比值(Read current ratio)，以及記憶體視窗(Memory window)的影響。為了減少功率消耗，並提高元件的可靠性，分析適合低壓操作的鐵電電容??? ? ???特性，並設計新型的鐵電記憶體單元(Memory cell)，包含使用低電壓讀取法(Low Voltage, LV)的 LV 1T1FeMFET 和 LV 2T1FeMFET 記憶體單元，使得鐵電電晶體
能操作在更低的電壓並改善記憶體視窗。
當鐵電電晶體的操作電壓為 1.5V，矯頑電場(Coercive Field, ??)為0.9??/??時，剩餘極化(Remanent Polarization, ??)較小(?? = 14??/??2)的鐵電電晶體，可以讀取到比剩餘極化較大(?? = 18??/??2) 的鐵電電晶體還更大的讀取電流比值和記憶體視窗，然而，當操作電壓提升至 2V 時，剩餘極化較大的鐵電記憶體(?? = 18??/??2)，反而可以看到
較大的讀取電流比值和記憶體視窗。而在寫入電壓於 1.5V 至 4V 的區間中，矯頑電場等於1.8??/??的鐵電電晶體，較小的剩餘極化(?? = 14??/??2)皆可以讀取到更大的讀取電流比值和記憶體視窗。
在操作電壓為 1.5V，鐵電電晶體的鐵電參數?? = 19??/??2、?? = 16??/??2、?? = 1.2??/??的情況，相較於單電晶體 1FeMFET 記憶體單元，LV 1T1FeMFET 記憶體單元能表現四倍大的記憶體視窗，LV 2T1FeMFET 記憶體單元則表現出約七倍大的記憶體視 窗； 在鐵 電 參數 ?? = 19??/??2、?? = 16??/??2、?? = 1.5??/?? 時， LV 1T1FeMFET 記憶體單元能讀取到比 1FeMFET 記憶體單元大將近六倍的記憶體視窗，LV 2T1FeMFET 記憶體單元則能讀取十倍以上的記憶體視窗；由此可知，使用低電壓讀取法(LV)的記憶體單元，除了在低電壓操作能看到好處外，當矯頑電場(??)較大時，其優點會更加顯著。;In this work, to reduce the power consumption and improve the reliability of FeMFET nonvolatile memory (NVM), we analyze the impact of ferroelectric parameters on the read
current ratio and memory window (MW). The low voltage read (LV) memory cells, including LV 1T1FeMFET and LV 2T1FeMFET memory cells, are proposed and analyzed at a wide operating voltage range from 1.5V to 4V.
For FeMFET with coercive electric field (??) equal to 0.9??/?? operated at 1.5V, smaller remanent polarization (?? = 14??/??2) exhibits larger read current ratio and MW than larger ??(18??/??2). However, as write voltage increases to above 2V, larger ??( 18??/??2) shows higher larger read current ratio and MW for FeMFET with ?? =
0.9??/??. For FeMFET with larger ??(?? = 1.8??/??), smaller ?? exhibits higher MW for write voltage ranging from 1.5V to 4V.
In the case of FeMFET memory cells operated at 1.5V and ferroelectric parameters ?? =19??/??2, ?? = 16??/??2, ?? = 1.2??/??, the MW of LV 1T1FeMFET memory cell is about four times larger than 1FeMFET memory cell, and the MW of LV 2T1FeMFET memory cell is about seven times larger than 1FeMFET memory cell. As the ferroelectric parameter ?? = 19??/??2, ?? = 16??/??2, ?? = 1.5??/??, the LV 1T1FeMFET memory cell shows nearly six times larger MW than the 1FeMFET memory cell, and the LV 2T1FeMFET memory cell gets more than ten times larger MW. Therefore, the proposed LV memory cells show benefits in low-voltage operation even for the ferroelectric layer designed with large ??. |
