Raman microprobe study of recrystallization in ion-implanted and laser-annealed polycrystalline silicon

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Abstract
Implantation-amorphized polycrystalline silicon layers which are directly deposited on single-crystal Si are annealed by a scanning cw laser. The crystallinity of the annealed layers has been examined by a Raman microprobe in combination with polarization measurements. The Raman spectra measured for the specimens annealed at various power levels reveal that the polysilicon layer is regrown liquid epitaxially and is transformed into single crystal at high annealing power levels and that the regrowth at lower power levels is governed by the mixture of solid and liquid epitaxial processes. It is found that for specimens annealed at high power levels the tensile stress in the annealed layer is relaxed to a certain extent, though the weak residual strain still remains. The Raman microprobe spectra from the boundary reigon between the annealed and amorphous layers are recorded by making the probe laser beam traverse the boundary region. This technique enables us to investigate the variation in crystallinity and the regrowth process in the boundary zone which is found to be less than 10 μm width.