Laser-Induced Thermal Stresses in Dense and Porous Silicon Dioxide Films

The laser-induced thermal stresses in silicon dioxide films are calculated using molecular dynamics simulations. The absorption of the laser energy is simulated by the linear temperature growth from room temperature to 1300 K in a time equal to the laser pulse duration. The maximum values of stresses for picosecond pulses are approximately twice as high as for nanosecond pulses. The stresses in highly porous glancing angle deposited films are approximately two times lower than in dense films. Stress waves caused by picosecond pulses are observed in dense films. An increase in the heating temperature to 1700 K leads to an increase in the absolute stress values for picosecond pulses, and a decrease for nanosecond pulses.

Atomistic Simulation of Stresses in Growing Silicon Dioxide Films

Dependence of stress values in silicon dioxide films on its thickness in the initial stage of film growth was investigated using atomistic molecular dynamics simulation. It was shown that the stress in normally deposited films was compressive and varied slightly with growth of film thickness. The stress in the glancing angle deposited films was several times lower than the stress in the normally deposited films, and varied from compressive stress to tensile stress with increasing film thickness. An essential anisotropy of stress tensor components was revealed for the case of glancing angle deposition. The calculated stress values were in the interval of experimental data.