Femtosecond laser ablation is an important process in micromachining and nanomachining of microelectronic,
optoelectronic, biophotonic and MEMS components. It is also important in the damage of optical components and
materials. A thorough understanding of all aspects of femtosecond matter interaction processes in the near-threshold
regime is required if one wants to have complete control of these processes. Two aspects of the interaction process for
metals and semiconductors are examined in detail in the present paper, namely the effect of a more complete model for
the temperature dependent electron thermal conductivity in metals and the avalanche ionization process in
semiconductors. These are included in two temperature and molecular dynamics modeling calculations respectively.
The proper inclusion of these processes allows the model calculations to better reproduce published experimental
measurements for copper and silicon.
Femtosecond laser ablation is an important process in the micromachining and nanomachining of microelectronic, optoelectronic, biophotonic and MEMS components. The process of laser ablation of silicon is being studied on an atomic level using molecular dynamics
(MD) simulations. We investigate ablation thresholds for Gaussian
laser pulses of 800 nm wavelength, in the range of a few hundred
femtoseconds in duration. Absorption occurs into a hot electron bath
which then transfers energy into the crystal lattice. The simulation
box is a narrow column approximately 6 nm x 6 nm x 80 nm with periodic
boundaries in the x and y transverse directions and a 1-D heat flow
model at the bottom coupled to a heat bath to simulate an infinite
bulk medium corresponding to the solid bulk material. A modified
Stillinger-Weber potential is used to model the silicon atoms. The
calculated thresholds are compared to various reported experimental
values for the ablation threshold of silicon. We provide an overview
of the code and discuss the simulation techniques used.