Final Project Proposal:
Molecular dynamic simulation of lattice defects in Silicon Nitride

Silicon nitride is used as a dielectric barrier in the silicon based devices industry, both in CMOS, VLSI and MEMS devices fabrication. Silicon nitride can be deposited onto the substrate via several deposition techniques. In the PECVD (Plasma Enhanced Chemical Vapor Deposition) a verity of lattice defect can form. Those defects can derive the mechanical proparties of the layer.

The aim of this project is to reproduce the silicon nitride lattice using the LAMMPS code, using the Tersoff potential [1,2] or other potentials, and to simulate the diffusion of the lattice defects, which include:

  1. Silicon vacancy
  2. Nitrogen vacancy
  3. Hydrogen inclusion [3]

Furthermore, a calculation of the average internal stress will be made for the lattice defects.
A visualization of the lattice will be realized using AViz.

Figure 1

Fig 1. A Silicon nitride thin film on a silicon wafer.
[from filmetrics, http://www.filmetrics.com/dielectrics]

References

  1. J. Tersoff, Phys. Rev. B, 39(8), 5566 (1989)
  2. F. de Brito Mota, J. F. Justo and A. Fazzio, Phys. Rev. B, 58(13), 8323 (1998)
  3. J. Houska, J. E. Klemberg-Sapieha and L. Martinu, J. Appl. Phys. 107, 083501 (2010)


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