鐵電效應於負電容電晶體與1T記憶體應用

Abstract

德國T. S. Böscke團隊在IEDM 2011發表的論文中提到，長久下來，在具有快速操作、低耗電及非揮發性記憶體技術中，鐵電場效應電晶體(FeFET)有著顯著的地位。 MOSFET的SS在常溫下根據Boltzmann tyranny其物理極限為2.3kbT/decade。為突破此極限則需改變SS公式中body factor，其中Cins可藉由絕緣層材料的選擇達成負電容，室溫之SS< 60mV/dec。 在FeRAM中，資料能長期的儲存在有極化效果的閘極絕緣層裡，並且利用元件的VT位移產生的window做非破壞性的資料讀取。此概念在已被實驗證明出，但在實作上難以達成非揮發性記憶體操作規格。 本研究的目標就是發展利用鐵電負電容，達到低次臨界擺幅次世代電晶體研究與1T記憶體，故於此研究將發展HfO2:Zr，造成極化效果。目標則是改善次臨界擺幅(subthreshold swing)與hysteresis window，讓資料能儲存於FeRAM中。The paper of T. S. Böscke’s team reported in IEDM 2011.The FeFET is a long-term contender for a fast, low power and nonvolatile memory technology. Physical limitation of Boltzmann tyranny with 2.3kbT/decade for MOSFET at room temperature restricts the switching slope. For break through the physical limitation, the equation of body factor of subthreshold swing must be< 1, the Cins turn into negative capacitance by select insulator material. Subthreshold swing will be < 60mv/dec. at room temperature. In FeRAM, information is permanently stored as polarization state of the gate insulator and can be read non-destructively as a shift of the threshold voltage. The FeRAM concept was experimentally demonstrated, but the practical implementation has remained elusive. In this study, we will develop the low swing FET and 1T Memory by negative capacitance concept. Therefore, we will develop HfO2:Zr to achieve polarization effect. The objective is to improve the subthreshold swing and hysteresis window let the information stored in FeRAM.