The Electrical Properties of Metal-Ferroelectric-Polysilicon-Insulator-Silicon (MFPIS) Capacitors and Field-Effect Transistors using PZT as the ferroelectric layer and Y2O3 as the insulator layer

• Main Authors: Po-Chin Chan, 詹博欽
• Other Authors: Joseph Ya-Min Lee
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/47157591864897137342

碩士 === 國立清華大學 === 電子工程研究所 === 96 === Ferroelectric field effect transistors (FeFETs) with a metal/ferroelectric/insulator/silicon (MFIS) structure is a promising candidate for non-volatile random access memory because of its high speed, single-device structure, low power consumption, and non-destructive read-out operation. However, the FeFET memory has the problem of short retention time. The short retention time was due to the depolarization field effect and it can be fully compensated because of the high conductivity of the floating gate. A high conductive n+-polysilicon floating gate was used to reduce the depolarization field of the ferroelectric layer. In this work, we used the metal/ferroelectric/polysilicon/insulator/silicon (MFPIS) structure to overcome the short retention problem. The purpose of the insulator layer is to prevent the reaction and inter-diffusion between the ferroelectric layer and silicon layer. The Y2O3 high dielectric constant film was used as the insulator layer. It has a dielectric constant of 12~18 and good thermal stability with silicon. In this work, MFPIS capacitors and field effect transistors with the structures of Al/PZT/polysilicon/Y2O3/silicon were fabricated. These devices were used to floating gate ferroelectric random access memory (FFRAM) cells because the depolarization filed can be reduced in this structure.