应变硅n-MOSFET中电子迁移率的增强及其温度特性

Electron Mobility Enhancement Characteristics and Its Temperature Dependence in Strained-Si n-MOSFETs

采用减压化学气相淀积(RPCVD)技术在弛豫Si_(1-x)Ge_x虚拟衬底上赝晶生长应变硅层,以其为沟道材料制造得到的应变硅n-MOSFET表现出显著的性能提升。研究了通过改变Si_(1-x)Ge_x中Ge的摩尔组分x以改变硅帽层中的应变以及在器件制造流程中通过控制热开销来避免应变硅层发生弛豫等关键问题。在室温下,相对于体硅器件,应变硅器件表现出约87%的低场电子有效迁移率增强,在相同的过驱动电压下,饱和漏端电流增强约72%。在293 K到353 K的温度范围内研究了反型层电子有效迁移率和饱和漏端电流随温度的变化,实验结果表明,当温度升高时应变硅材料的电子迁移率增强倍数保持稳定。

Enhanced performance is demonstrated in n-MOSFETs with channel regions formed by pseudomorphic growth of strained-Si on relaxed Si1-xGex using reduced pressure chemical vapor deposition （RPCVD） technique. The Ge composition x of Si1-xGex was varied to introduce different strain into the Si cap layer. Thermal budget was carefully controlled in the device fabrication process to avoid strain relaxation. At room temperature, the strained-Si n-MOS-FETs show a significant mobility enhancement of ～87% over Si control devices at low vertical field and the drain current of long channel devices is increased by ～72% for the same gate over- drive. The temperature behavior, including the variations of the inversion layer electron effective mobility and the saturated drain current, was investigated within a range from 293 K to 353 K. It is found that strained-Si material provides stable electron mobility enhancement as the temperature increases.