Drive-Current Enhancement in FinFETs Using Gate-Induced Stress

A novel and simple process for the exploitation of metal-gate-induced stress in the Si channel region of a FinFET is reported. TaN metal-gate electrode was employed. The use of a silicon nitride capping layer, which covered the metal gate during the source and drain anneal, led to a large stress being developed as a result of the thermal-expansion coefficient mismatch between the gate and the capping layer. The resulting strain was retained and transferred to the Si channel. The stress introduced by the gate stressor was found to enhance the performance of the n-channel FinFETs and is believed to be tensile in the source-to-drain direction. This approach may be applicable to other metal-gate materials having a mismatch in the thermal-expansion coefficient with surrounding capping materials.