MFIS结构：未来Fe-NCFETs的关键选择

In 2008, Salahuddin and Datta proposed a novel approach to enhance the gate voltage of devices by using ferroelectric materials instead of traditional gate dielectric materials. This method theoretically reduces the device SS and is called the MFS structure (Figure 3.1(a)), which has the advantage of a simple structure. However, the incompatibility between the ferroelectric layer and the channel results in poor interface performance. To address this issue, the MFIS structure was proposed, which adds a traditional gate dielectric layer between the ferroelectric layer and the channel. This structure successfully solves the interface problem, but the voltage amplification effect of the ferroelectric material in the channel direction is different due to the variation of the channel surface potential between the source and drain, while the surface potential distribution on the ferroelectric layer is uniform. To solve this problem, some propose adding a metal layer between the gate dielectric layer and the ferroelectric layer, i.e., the MFMIS structure. However, this structure increases device manufacturing difficulty, is unfavorable for further reducing device size, and increases gate leakage current, lowering device stability. Compared to the MFMIS structure, the capacitance matching of the MFIS structure NCFET is more stable. Therefore, the MFIS structure remains the main choice for future Fe-NCFETs.