(100)Si基应变p型金属氧化物半导体[110]晶向电导率有效质量双椭球模型

利用应变技术和沟道晶向工程技术,均可有效增强Si基金属氧化物半导体器件的性能.本文提出了(100)Si p型金属氧化物半导体(PMOS)110]晶向电导率有效质量双椭球模型,从理论上解释了Si PMOS100]晶向沟道空穴迁移率为110]晶向沟道空穴迁移率1.15倍的原因.基于(100)Si基应变PMOS反型层E-k关系,拓展应用该模型,首先获得了(100)Si基应变PMOS反型层价带第一子带等能图,然后给出了(100)Si基应变PMOS器件反型层110]晶向空穴电导率有效质量模型.本文的模型方案合理可行,可为Si基应变PMOS器件的研究与设计提供有价值的参考.

Double ellipsoid mo del for conductivity effective mass along [110] orientation in (100) Si-based strained p-channel metal-oxide-semiconductor

The performance of a Si metal-oxide-semiconductor field-effect transistor can be enhanced effectively by the strain technology and the orientation engineering. For example, the 110] direction is usually used as the channel direction in the Si p-channel metal-oxide-semiconductor (PMOS) on <100> oriented substrate. While SunEdison company rotates the channel direction 45 degrees to the 100] direction, its hole mobility is 1.15 times larger than the hole mobility of the former.The orientation engineering is based on the anisotropy of the hole effective mass along different directions. The enhancement of carrier mobility naturally occurs when we choose the direction with the smaller carrier effective mass as the channel direction.However, according to the reported results in the literature, the hole effective mass values along the 110] and 100] orientation are about 0.6m₀ and 0.29m₀, respectively. The former is twice larger than the latter, which cannot explain that the experimental result increases 1.15 times.We find that the effective mass values along both the long axis and the short axis should be taken into consideration, and the value of 0.6m₀ can only represent the long axis term by observing the equivalent energy diagram of the first sub-band in Si PMOS.In view of this, the double ellipsoid model is given for the conductivity effective mass along the 110] direction in (100) Si PMOS, which explains the reason why the hole mobility along the 100] direction is 1.15 times larger than that along the 110] direction in Si PMOS. And then, based on the E-k relation of the inversion layer in Si-based strained PMOS, we study the conductivity effective mass along the 110] direction in (100) Si-based strained PMOS by the above method.The results show that 1) the 110] oriented hole conductivity effective mass of biaxially strained Si PMOS can be calculated directly by its spherical equivalent energy diagram; 2) in the case of biaxially strained Si_1-xGe_x PMOS, its conductivity effective mass needs to be calculated by the double ellipsoid method; 3) the 110] oriented hole conductivity effective mass of uniaxially strained Si PMOS should be solved approximately by two different sizes of ellipsoid.Our valid models can provide the valuable references for studying and designing the Si-based strained PMOS device.