Grain Size and Resistivity of LPCVD Polycrystalline Silicon Films

Measurements have been performed on phosphorous‐implanted polysilicon films and TEM investigation has given indications about the mean grain size and about its dependence on the temperature and duration of annealing. Results have also been obtained concerning the sheet resistivity of the films. A semiquantitative model has been derived which attempts to explain the variation in sheet resistivity as a function of the doping level. The observation of both grain size and sheet resistivity suggests that not only segregation to grain boundary and grain growth occur during annealing but that a third phenomenon (a crystallographic relaxation at grain boundary) should occur at a temperature of about 1000°C.