The cleaving process has the potential to replace the dicing of thin wafers. Its inherent advantages are no mechanical
forces to the substrate, no material losses, and high edge quality. In order to determine the fundamental mechanisms
leading to a reliable cleaving process the complex interaction of wavelength and temperature dependent absorption, heat
transfer, material elongation and finally crack formation is theoretically described and experimentally verified. A
successful process observed if sufficient thermal stress can be generated to induce a crack and if no surface deformation
occurs due to overheating. Most relevant parameters determining the process window are irradiated power, cutting speed,
and focus spot size. The results of these parameter variations are presented. Accuracy and reproducibility is
demonstrated by cleaving stripes of different widths fulfilling the requirements of the electronic packaging industry. In
the third section the influence of the crystalline orientation is investigated. As a result mono-crystalline silicon exhibits
an anisotropic behaviour when changing the cutting direction whereas for polycrystalline substrates a permanent change
of the crystal structure is found at the grain boundary. Finally, the obtainable edge quality is presented briefly, which
leads to higher sample strengths compared to conventional laser and mechanical processes.
Global warming is a current topic all over the world. CO2 emissions must be lowered to stop the already started climate
change. Developing regenerative energy sources, like photovoltaics and fuel cells contributes to the solution of this
problem. Innovative technologies and strategies need to be competitive with conventional energy sources. During the last
years, the photovoltaic solar cell industry has experienced enormous growth. However, for solar cells to be competitive
on the longer term, both an increase in efficiency as well as reduction in costs is necessary. An effective method to
reduce costs of silicon solar cells is reducing the wafer thickness, because silicon makes up a large part of production
costs. Consequently, contact free laser processing has a large advantage, because of the decrease in waste materials due
to broken wafers as caused by other manufacturing processes. Additionally, many novel high efficiency solar cell
concepts are only economically feasible with laser technology, e.g. for scribing silicon thin-film solar cells. This paper describes laser hole drilling, structuring and texturing of silicon wafer based solar cells and describes thin
film solar cell scribing. Furthermore, different types of lasers are discussed with respect to processing quality and time.
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