亚0.1 μm栅衬互连体硅MOSFET特性研究

Research on sub 0.1μm gate body connected bulk MOSFET

为满足低电压ＣＭＯＳ晶体管高驱动电流和低静态功耗的要求，提出０．５Ｖ栅衬互连ＧＢＣ（ｇａｔｅ－ｂｏｄｙｃｏｎｎｅｃｔｅｄ）体硅ＭＯＳＦＥＴ工作模式。利用二维器件模拟，对栅长直到７０μｍ的器件结构设计、特性和器件物理研究。得到结果：０．５ＶＧＢＣ－ＭＯＳＦＥＴ具有陡直的亚阈特性（１０倍电流的Ｓ因子为～６０ｍＶ），高的电流驱动能力和理想的逻辑摆幅，栅衬泄漏电流可以忽略；超浅源漏、非均匀纵横向掺杂的Ｅｘｐｏｃ结构在ＧＢＣ模式下栅长直到５０ｎｍ时，仍有很好的Ｖｔｈ可控制性，这一结构的０．５ＶＧＢＣ－ＭＯＳＦＥＴ与１Ｖ常规ＭＯＳＦＥＴ在宽广的阈值电压设计空间中具有相似的速度品值；其理想栅氧厚度为３ｎｍ。

High current driving capability and low standby power dissipation are now becoming an increasingly important subject in low voltage CMOS transistor design. This paper proposed a Gate body Connected (GBC) operation mode for bulk MOSFET at 0.5V power supply voltage to deal with this issue. Based on two dimensional device numerical simulations, this work covers the research on device structure design, characteristics and physics in 0.5V GBC bulk MOSFET down to sub 0.1μm gate length. The major results obtained can be summarized as: first, 0.5V GBC operation features steep turn off behavior, high current drive, ideal logic voltage swings and negligible gate to body leakage currents; secondly, an Expoc structure which has shallow source/drain extensions and non uniform vertical and lateral doping profiles shows excellent threshold voltage ( V th ) rolloff down to 50nm gate length and high immunity of V th against channel doping fluctuations under the GBC mode of operation; and finally 0.5V GBC MOS transistors show comparable figure of merit in speed performance with 1V conventional counterpart in a wide V th design space. Furthermore, it is found that the optimum gate oxide thickness for 0.5V sub 0.1μm GBC MOSFETs would be 3nm.