High Tensile Strained In-Situ Phosphorus Doped Silicon Epitaxial Film for nMOS Applications

In-situ phosphorus doped silicon epitaxial film with 2.8 X 1021cm-3 doping level is found to show high tensile stress comparable to carbon doped silicon with 1.8% substitutional carbon. As-grown samples show electrically activated dopant concentration of less than 2 X 1020 cm-3. The high tensile and low activation could be well explained by formation of a pseudocubic Si3P4 structure in silicon lattice. Film resistivity of 0.29 mOhm-cm could be obtained with 0.25 ms annealing at 1200 {degree sign}C, with slight reduction in tensile strain. Also, 0.23 mOhm-cm could be obtained by millisecond anneal at 1300 {degree sign}C, but with 30% reduction in tensile strain.