Physical mechanisms of short-pulse laser ablation

1999 ◽  
Author(s):  
Dietrich von der Linde ◽  
Klaus Sokolowski-Tinten
Keyword(s):  
Laser Ablation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Physical Mechanisms ◽  
Short Pulse Laser

Silicon Thinning using Ultra-Short Pulse Laser Ablation

2004 ◽  
Author(s):  
F. Beaudoin ◽  
P. Perdu ◽  
C. DeNardi ◽  
R. Desplats ◽  
J. Lopez ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Sample Preparation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Special Care ◽  
Short Pulse Laser ◽  
Ultra Short Pulse ◽  
Ultra Short Pulse Laser

Abstract Ultra-short pulse laser ablation is applied to IC backside sample preparation. It is contact-less, non-thermal, precise and can ablate the various types of material present in IC packages. This study concerns the optimization of ultra-short pulse laser ablation for silicon thinning. Uncontrolled silicon roughness and poor uniformity of the laser thinned cavity needed to be tackled. Special care is taken to minimize the silicon RMS roughness to less than 1µm. Application to sample preparation of 256Mbit devices is presented.

The Metal-Dielectric Transition in Short-Pulse Laser Ablation of Metals

Volume 4 ◽  
2004 ◽  
Author(s):  
Cristian Porneala ◽  
David A. Willis
Keyword(s):  
Laser Ablation ◽  
Absorption Coefficient ◽  
Phase Change ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Phase Explosion ◽  
Short Pulse Laser ◽  
Dielectric Transition

Phase explosion is an explosive liquid-vapor phase change that occurs during short pulse laser ablation. Phase explosion results from homogenous vapor nucleation in a superheated liquid phase as the surface temperature approaches the thermodynamic critical temperature, Tc. For a metastable liquid, the upper limit of superheating is approximately 0.9Tc, above which the rate of homogeneous nucleation rises dramatically. Prior to reaching the superheat limit however, a “dielectric transition” is expected to occur at approximately 0.8Tc. The dielectric transition is the transition of an electrically conductive material to a non-conducting state due to large fluctuations in material properties. One consequence of the dielectric transition is that the material will become semi-transparent. Until now, little work has been performed to understand the role of the dielectric transition in laser ablation, and many questions remain about how the surface will rise above 0.8Tc if the surface is semitransparent and only weakly absorbing. This work investigates the role of the dielectric transition with a one-dimensional numerical model for heat transfer and phase change and includes the effect of the metal to dielectric transition. The model is used to simulate heating of aluminum by a Nd:YAG laser with a 7 nanosecond pulse width (FWHM) at the fundamental wavelength of 1064 nm. Calculations of the transient temperature field, melt depth, and depth of the dielectric layer are obtained. Estimates of the absorption coefficient of a metal surface above the metal-dielectric transition are made from correlations found in the research literature. The value of the absorption coefficient is shown to be a critical parameter for determining the energy density required to reach 0.9Tc.

Correlation between ablation efficiency and nanoparticle generation during the short-pulse laser ablation of metals

Laser Physics ◽  
2008 ◽  
Vol 18 (4) ◽  
pp. 374-379 ◽  
Author(s):  
J. Hermann ◽  
S. Noël ◽  
T. E. Itina ◽  
E. Axente ◽  
M. E. Povarnitsyn
Keyword(s):  
Laser Ablation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Ablation Efficiency ◽  
Short Pulse Laser ◽  
Nanoparticle Generation

Micromachining of silicon by short-pulse laser ablation in air and under water

2004 ◽  
Vol 372 (1-2) ◽  
pp. 145-162 ◽  
Author(s):  
K.L. Choo ◽  
Y. Ogawa ◽  
G. Kanbargi ◽  
V. Otra ◽  
L.M. Raff ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Pulse Laser ◽  
Pulse Laser Ablation ◽  
Short Pulse ◽  
Short Pulse Laser
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