More than 80 % of the current solar cell production requires the cutting of large silicon crystals. While in the last years the cost of solar cell processing and module fabrication could be reduced considerably, the sawing costs remain high, about 30 % of the wafer production. At present the large crystals are cut using the multi‐wire slicing technology[2] which has the advantage of a high throughput (several hundred wafers per day and machine), a small kerf loss of about 200 μm and almost no restrictions on the size of the ingots. Basic knowledge about the microscopic details of the sawing process is required in order to slice crystals in a controlled way. In the following the principles of the sawing process will be described in this review article as far as they are understood today.

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Oxygen and carbon are the main impurities in multicrystalline silicon for photovoltaic applications. Precipitation of oxygen and carbon occurs during crystal growth and solar cell processing. Depending on the thermal conditions and the initial oxygen and carbon content various types of SiO 2 , SiC precipitates and oxygen related defects are observed and investigated by IR spectroscopy and transmission electron microscopy. Topographic m-PCD measurements are used to study the minority carrier lifetime in the material locally. It is found that certain types of oxygen defects reduce the lifetime of the bulk and enhance the recombination activity of dislocations. Quantitative measurements of the oxygen precipitation of pre-annealed specimens are carried out to study the oxygen precipitation systematically. A statistical nucleation and growth model using rate equations and a Focker-Planck equation is applied to simulate the precipitation process numerically.

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The statistical fracture stress distribution of silicon wafers was obtained by biaxial plate bending tests in combination with finite element calculations. For the correct interpretation of these tests it is important that the finite element calculations imply wafer thickness and elastic properties of the multicrystalline silicon wafer, otherwise the resulting stresses will be estimated to high. The Weibull distribution of fracture stresses yields different parameters for each test series of silicon, depending on the surface preparation and wafer manufacturing condition.