Ultralow-Thermal-Budget CMOS Process Using Flash-Lamp Annealing for 45 nm Metal/High- $k$ FETs

This paper describes a fabrication process that uses flash-lamp annealing (FLA) and the characteristics of the CMOS transistors that are constructed with an ultralow-thermal- budget process tuned for 45-nm metal/high-k FETs. FLA enhances the drivability of pFETs with the solid-phase epitaxial (SPE) extension junction, but reducing the thermal budget deteriorates the poly-gate depletion and the electron mobility. Metal gate, however, prevents the depletion problem and leads to higher drain currents and better threshold-voltage (V_TH) roll-offs when processed with tilted extension implantation combined with SPE + FLA than when processed with untilted extension implantation combined with spike rapid thermal annealing. Reducing the thermal budget is also effective in obtaining low V_TH values in p-metal/HfSiON gate because of the reduced vacancy formation. Moreover, cluster-boron implantation for pFETs has superiority over monomer-boron implantation with Ge postamorphous implantation in terms of V_TH roll-offs and I_on-I_off´s if FLA is used as activation. The superior electrical characteristics of full-metal- gate HfSiON transistors whose gate length is less than 50 nm, which are fabricated by using the FLA process, are demonstrated.