SEM OVERESTIMATION OF THE MEAN GRAIN-SIZE OF CHEMICALLY ETCHED POLYCRYSTALLINE SILICON FILMS

Scanning electron microscopy (SEM) has been employed to investigate th e mean grain sizes of P-doped polycrystalline silicon films produced b y low-pressure chemical vapour deposition (LPCVD). A chemical etching standard procedure has been used to obtain SEM high contrast between p olycrystalline grains and their boundaries. It has been found that thi s method, often used in materials laboratories, may cause a large over estimation of the layer's mean grain size. A simple model explaining t he obtained results has been proposed.