High-Performance Si0.45Ge0.55 Implant-Free Quantum Well pFET With Enhanced Mobility by Low-Temperature Process and Transverse Strain Relaxation

In this paper, we have fabricated high-performance Si<sub>0.45</sub>Ge<sub>0.55</sub> implant-free quantum well (IFQW) pFET with embedded SiGe source/drain stressor. This device showed high drive current of 1.28 mA/μm at I<sub>OFF_D</sub> of 160 nA/μm with channel length/width of 30 nm/0.16 μm (V<sub>DD</sub> = -1 V). Conventional ion-implanted extension is replaced with in situ borondoped epitaxial Si0.75Ge0.25 layer. This enables lower process temperature which can maintain an integrity of Si<sub>0.45</sub>Ge<sub>0.55</sub> film and thus higher hole mobility. In narrower width devices, we observed significant hole mobility boost (1.9× improvement from active width of 10 to 0.1 μm). This is due to the relaxation of unwanted transverse stress in Si<sub>0.45</sub>Ge<sub>0.55</sub> channel applied from Si substrate. IFQW devices show improved short channel control thanks to the epitaxially formed raised extension structure compared with conventional devices which have implanted extension. Achieved device performance is one of the best among all Si<sub>1-x</sub>Ge<sub>x</sub>-based channel pFET up to date.

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