小尺寸单轴应变Si PMOS沟道晶面/晶向选择实验新发现

New experimental discovery of channel crystal plane and orientation selection for small-sized uniaxial strained Si PMOS

小尺寸单轴应变Si p型金属氧化物半导体(PMOS)沟道反型层迁移率与晶面/晶向密切相关,应变PMOS优化设计时应合理选择沟道的晶面/晶向.目前,文献已有1.5 GPa应力强度下单轴应变Si PMOS沟道反型层迁移率按晶面/晶向排序的理论模型.然而,在器件实际制造过程中,覆盖SiN应力膜工艺是固定的,由于沟道弹性劲度系数具有各向异性,这样,不同晶面/晶向应变PMOS沟道所受应力强度不同,进而导致在实际工艺下沟道反型层迁移率晶面/晶向排序理论模型"失效".针对该问题,本文采用中国科学院微电子研究所40 nm工艺流程制备了不同晶面/晶向40 nm沟道小尺寸单轴应变Si PMOS与未应变Si PMOS,并通过器件转移特性测试,获得了小尺寸单轴应变Si PMOS反型层迁移率晶面/晶向排序结论.此有关小尺寸单轴应变Si PMOS沟道反型层迁移率晶面/晶向排序的相关结论,由于考虑了工艺实现因素,与文献理论预测排序结果相比,更适于指导实际器件制造;相关分析方法也可为其他应变材料沟道MOS相关问题的解决提供重要技术参考.

The inversion layer mobility of small-sized uniaxial strained Si p-channel metal oxide semiconductor （PMOS） channel is closely related to the crystal plane and crystal orientation. When optimally designing the strained PMOS, the crystal plane and crystal orientation of the channel should be chosen reasonably. At present, there is a theoretical sort model for the inversion layer mobility of Si PMOS channel at 1.5 GPa stress according to the crystal plane and crystal orientation. However, in the actual manufacturing process of device, the process of covering the SiN stress film is fixed, because the channel coefficient of stiffness is aeolotropic. So, the stress intensities of strained PMOS in different crystal planes and orientation channels are different, which causes the theoretical sort model for the inversion layer mobility to be invalid. To solve this problem, the small-sized uniaxial strained Si PMOS and unstrained Si PMOS with different crystal planes and orientations are fabricated by 40 nm technological process of Chinese Academy of Sciences. The result for the inversion layer mobility of Si PMOS channel according to the crystal plane and crystal orientation is obtained by the device transfer characteristic test. Considering the process implementation factors, the relevant conclusion about the inversion layer mobility of small-sized uniaxial strained Si PMOS channel according to the crystal plane and crystal orientation is more suitable to guide the actual device manufacturing than the theoretical sort result predicted in the literature. At the same time, the relevant analysis method can also provide important technical reference for the solution of other strained material MOS.