Quantum Effect And The Influence Of Structure Parameters On The Tunneling Transistor Characteristics

With the increasing of device density in the integrated circuit, the issues of the power dissipation in the conventional planar metal oxide semiconductor field effect transistor (MOSFET) become more prominent. In order to develop the low power device, a lot of researches have been carried out. Among them, the tunneling field effect transistor (TFET) has the potential to be used as low power device due to its unique working principle. In this thesis, we apply technology computer aided design (TCAD) tools to investigate the impact of quantum effects and device parameters on the characteristics of TFET.In the first chapter, we introduce the background and significance of this work. In the second chapter, we describe the TCAD device simulation tools, the using methods, and the other relavant issues. In the third chapter, we first introduce several basic quantum effects in TFET. And then, the impact of quantum statistics and quantum confinement effects on the characteristics and reliability of TFET is studied and compared with traditional MOSFET characteristics. In the fourth chapter, the impact of device parameters on the characteristics and reliability of TFET have been studied, including the impact of size reduction, gate dielectric constant, gate overlap, and doping profile in tunneling junction. In the fifth chapter, the parameter optimization of an improved TFET, i.e., the PNIN TFET, has proposed.The main conclusions of the thesis are:(1) When studing positive bias temperature instability (PBTI) of the TFET and MOSFET, quantum effects should been considered. And the impact of quantum effects on the PBTI degradation of MOSFET is more serious than that of the TFET.(2) The decrease of the gate oxide thickness (tox) and body silicon thickness (TSi) can improve the IdVg characteristics of device. When the channel length (LC) is reduced to10nm, the device IdVg characteristics and reliability show little change. So the short-channel effect of TFET is not important. In addition, the gate overlap and the increase of gate dielectric constant under the same equivalent oxide thickness will make the IdVg characteristics and reliability of the device worse. The impact of the different doping profile in the tunneling junction on the characteristics of TFET is neglegible.(3) For an improved (PNIN) TFET, when the inserted N-layer thickness (Ln) in the tunneling junction is about10nm, the fluctuation of the threshold voltage duo to the fluctuation of Ln is minimum. With the increase of the inserted N-layer doping concentration (Nn), the IdVg characteristics and reliability of the device is improved. In addition, with the decrease of body Si thickness, the overall characteristics of the device change little.