Properties of furnace-annealed, high-resistivity, arsenic-implanted polycrystalline silicon films

Abstract

The approach to equilibrium of the grain structure and electrical properties has been studied in high-resistivity, As-implanted polycrystalline silicon films on thermally oxidized silicon wafers. Thermal annealing parameters are found to be critical in determining the film sheet resistance. Results from spreading resistance analysis, secondary ion mass spectroscopy, and transmission electron microscopy indicate that As diffusion down the grain boundaries into the film leads to a large fraction of the As being left in inactive grain boundary sites. Reactivation of the As is negligible when processing temperatures are 900 °C or lower. A relatively simple diffusion model has been developed that can fit the As concentration profile over the entire film thickness. This makes the model applicable to normal integrated circuit processing conditions where film thickness effects and nonequilibrium dopant distributions are important.