A method and apparatus for selective material removal and via drilling for
semiconductor applications using an ultrafast laser pulse directly from
an ultrafast pulse laser oscillator without amplification are disclosed.
The method and apparatus includes techniques to avoid/reduce the
cumulative heating effect and to avoid machine quality degrading in multi
shot ablation. Also the disclosed method and apparatus provide a
technique to change the polarization state of the laser beam to reduce
the focused spot size, and to improve the machining efficiency and
quality. The disclosed method and apparatus provide a cost effective and
stable system for high volume manufacturing and inspection applications.
The disclosed method and apparatus have particular applications in, but
not limited to, drilling vias for interconnect formation, selective
material removal for application specific integrated circuits, selective
material removal for flash memory applications, exposing layers for
further semiconductor processing such as wire bonding etc. The ultrafast
laser oscillator can be a called a femtosecond laser oscillator or a
picosecond laser oscillator depending on the pulse width of the laser
beam generated.