Numerical simulation of multiple scattering for modeling speckle roughness analyses on vertical surface regions of silicon wafers

Laser speckle measurement methods enable the roughness analysis also for vertical regions of silicon wafers. However, we have to calculate upon disturbing intensities that are generated by multiple reflection from the surrounding surfaces. A numerical simulation will be described in this study by which the higher spatial frequency of multiple scattered speckle intensities can be shown. Since focused laser beam is generally used for this purpose the influences of convergent illumination will also be taken into account. The results confirm the feasibility of speckle measurement methods (speckle-contrast, speckle-correlation) for roughness analysis of inaccessible surface regions of microstructures (side walls of grooves, inside surfaces of borings). Also, practically undetectable effects can be analysed through the calculation algorithm.