Embodiments of the present invention generally provide methods and
apparatus for material removal using lasers in the fabrication of solar
cells. In one embodiment, an apparatus is provided that precisely removes
portions of a dielectric layer deposited on a solar cell substrate
according to a desired pattern and deposits a conductive layer over the
patterned dielectric layer. In one embodiment, the apparatus also removes
portions of the conductive layer in a desired pattern. In certain
embodiments, methods for removing a portion of a material via a laser
without damaging the underlying substrate are provided. In one
embodiment, the intensity profile of the beam is adjusted so that the
difference between the maximum and minimum intensity within a spot formed
on a substrate surface is reduced to an optimum range. In one example,
the substrate is positioned such that the peak intensity at the center
versus the periphery of the substrate is lowered. In one embodiment, the
pulse energy is improved to provide thermal stress and physical lift-off
of a desired portion of a dielectric layer.