Effect of thermal annealing on the strain and microstructures of in-situ phosphorus-doped [formula omitted] films grown on blanket and patterned silicon wafers

Abstract

In this study, in-situ phosphorus-doped Si1−xCx layers were epitaxially grown on blanket and patterned Si wafers using reduced pressure chemical vapor deposition (RPCVD). The effect of post-growth annealing on the strain and microstructures of the epilayers was investigated by high resolution X-ray diffraction (HR-XRD), Raman scattering, and high resolution transmission electron microscopy (HR-TEM) analyses. Structural investigation revealed that induced tensile strain became significantly less at temperatures over 900°, as confirmed by Raman scattering measurements of SiC vibration modes. Furthermore, strain relaxation and substantial Csub loss were found in XRD and Raman data of Si:C samples annealed at 1000°, resulting from the generation of defects such as β-SiC precipitates or dislocations in Si1−xCx epilayers. Moreover, our microstructural analyses using TEM showed the formation of the β-SiC precipitates during rapid thermal annealing (RTA) over 900° and an increase in their number and size with annealing temperatures up to 1000°. Finally, we examined the impact of thermal annealing on the local strain and microstructures of patterned Si1−xCx samples with different structures. Our findings will provide greater insight into evaluating the strain states and microstructure of as-grown and annealed P-doped Si1−xCx films on both blanket and patterned Si wafers.