Ion beam synthesis of IrSi3 by implantation of 2 MeV Ir ions

摘要

Formation of a buried IrSi(sub 3) layer in (111) oriented Si by ion implantation and annealing has been studied at an implantation energy of 2 MeV for substrate temperatures of 450--550C. Rutherford backscattering (RBS), ion channeling and cross-sectional transmission electron microscopy showed that a buried epitaxial IrSi(sub 3) layer is produced at 550C by implanting (ge) 3.4 (times) 10(sup 17) Ir/cm(sup 2) and subsequently annealing for 1 h at 1000C plus 5 h at 1100C. At a dose of 3.4 (times) 10(sup 17) Ir/cm(sup 2), the thickness of the layer varied between 120 and 190 nm and many large IrSi(sub 3) precipitates were present above and below the film. Increasing the dose to 4.4 (times) 10(sup 17) Ir/cm(sup 2) improved the layer uniformity at the expense of increased lattice damage in the overlying Si. RBS analysis of layer formation as a function of substrate temperature revealed the competition between the mechanisms for optimizing surface crystallinity vs. IrSi(sub 3) layer formation. Little apparent substrate temperature dependence was evident in the as-implanted state but after annealing the crystallinity of the top Si layer was observed to deteriorate with increasing substrate temperature while the precipitate coarsening and coalescence improved.