New methods to evaluate cleaning processes by detecting the particle load on surfaces of diamond wire sawn silicon wafers
Wafers for solar cell processing do not only have to fulfill high geometric requirements but also have to be as free of any contaminations as possible. Therefore the wafering process is followed by several cleaning steps whereby contaminations such as organics, metals and particles should be removed from the wafer surface. With increasing requirements the cleaning process has to be continuously improved. However, up to now there is no known method that allows a reproducible qualitative or quantitative detection of the remaining particle load at diamond wire sawn wafer surfaces. To evaluate the influence of modified cleaning methods on particular contamination a suitable detection method is absolutely indispensable. In this work two new methods are introduced making it possible to detect the remaining particle load on wafer surfaces. For the first time, quantitatively reproducible results are obtained for the particle load either as a sum parameter or as a grain size dis tribution. The functionality of the methods is evaluated to compare the effectiveness of different cleaning procedures on the final cleaning step in the wafering process.