Stress management for CESL based strained PMOSFET using trench structure

We demonstrate a trench based structure to modulate the stress induced by the contact etch stop layer (CESL) in strained MOSFET. The strained PMOSFETs with gate length varying from 45 nm to 225 nm are simulated to investigate the effects of the trench based structure on channel stress. The calculation results show that, for the device strained by a tensile CESL, the application of such a structure successfully changes the channel state of stress from tensile to compressive. In combination with the conventional strained Si technology, this novel approach provides a solution to enhance the performance of PMOSFET and NMOSFET simultaneously using a single type strained CESL.