An Investigation of the Effect of Elastic Constants of Spacer in n-FETs CESL Stressor

The strained-Si approach from the contact etching stop layer (CESL) stressor with two kinds of Young´s modulus spacer has been investigated. From the TSUPREM4 simulation of the CESL tensile stressor, the tensile channel stress induced by the SiN spacer material is found to be 60% more than that by the oxide spacer material. With the use of a tensile CESL stressor for the 90-nm n-FETs, an extra 10% enhancement in drive current I_Dsat was obtained in the device with a high Young´s modulus (270-290 GPa) SiN spacer as compared with that with a low Young´s modulus (66 GPa) SiO₂ spacer. The electrical data are in good agreement with the prediction of the stress simulation.