Chien-Chao Huang

Molecular Dynamic simulation study of stress memorization in Si dislocations

Stress-Memorization-Technique by Si dislocations is effective in enhancing NFET device performance [1,2]. For the first time, MD (Molecular Dynamic) simulations are applied to explain the formation mechanism of dislocations during the Solid-Phase-Epitaxy-Regrowth (SPER) process. A semi- empirical TCAD method based on lattice-KMC (L-KMC) is then developed to predict dislocation formation. The simulated dislocation positions agree well with silicon experiments characterized by TEM. TCAD simulations show that the resulting dislocations are along the [111] direction and provide ~650MPa average longitudinal stress in channel regions, consistent with Nano-Beam-Diffraction (NBD) strain measurement. The channel stress is predicted by simulation to further increase by 1.5X after the poly-silicon gate removal step in a replacement-gate process. The dislocation SMT enhances NFET electron mobility by 25% and Ion-Ioff performance by 15%.