Antimony implanted strained Si for nMOSFET applications

Abstract: Incorporation of implanted antimony (Sb) in strained-silicon (s-Si) formed on relaxed-SiGe virtual substrates (10 and 30% Ge) has been studied. The implantation doses were 5×1013- 5×1014 cm-2 with an energy of 20 keV. The activation of dopant was performed by an rapid thermal annealing (RTA) treatment at 700 and 800 °C for 30 sec. Projected range of this implantation is about 20 nm which was also confirmed by different techniques. The layers were analyzed in terms of strain relaxation, sheet resistance, thermal stability, defect generation and dopant incorporation. X-ray diffraction (XRD), high-resolution reciprocal lattice mapping (HRRLM), transmission electron microscopy (TEM), secondary ion mass spectrometry (SIMS), Rutherford backscattering (RBS), four-probe measurements and Hall measurements were applied as characterization tools. This work demonstrates that the Sb incorporation in Si has improved in the presence of strain. The strain amount in s-Si does not alter after implantation or subsequent thermal treatment for dopant activation. The Sb-implanted s-Si layer on Si0.70Ge0.30 virtual substrate (5×1014 cm-2 700 °C, 30 sec RTA) demonstrated substitutional Sb concentration of 2.5×1020cm-3 where the same dose for a Si reference sample could only show 1×1020 cm-3. The fraction of active-to-atomic concentration of Sb-implanted Si was estimated nearly to 90%. HRTEM micrographs of Sb-implanted annealed samples illustrate almost defect-free material.