Stress damage process of silicon wafer under millisecond laser irradiation

Abstract

The stress damage process of a single crystal silicon wafer under millisecond laser irradiation is studied by experiments and numerical simulations. The formation process of low-quality surface is monitored in real-time. Stress damage can be observed both in laser-on and -off periods. Plastic deformation is responsible for the first stress damage in the laser-on period. The second stress damage in the laser-off period is a combination of plastic deformation and fracture, where the fundamental cause lies in the residual molten silicon in the ablation hole.

Comparison of 20- to 1000-Hz pulsed laser and continuous laser ablation of single-crystal germanium wafers

“…When the temperature rise of a material involves a phase change, the equivalent specific heat capacity method is used to deal with the problem. The equivalent specific heat capacity can be expressed as 19 cp,eff=cp+LmD+LvD,where Lm and Lv are the latent heats of melting and vaporization, respectively, and D represents the pulse function located at the melting and boiling points, which can be expressed as 19 D=exp[−(T−Tm,v)2/(ΔTm,v)2]πΔTm,v,where Tm,v represents the melting and boiling points and ΔTm,v is the pulse width, set to 10 K.…”

“…The heat loss due to thermal convection and thermal radiation can be expressed as 19 −kΔT=h(T0−T)+εeσ(T04−T4),where ΔT is the temperature rise of the material, T0 is the ambient temperature and is set to 298 K, εe is the surface emissivity of the material, and σ is the Stephen Boltzmann constant.…”