Effects of phosphorus on stress of multi-stacked polysilicon film and single crystalline silicon

Abstract

In multi-stacked polysilicon films, the stress was examined in terms of dopant distribution and the polysilicon/polysilicon interface at which phosphorus and oxygen atoms were piled up. The phosphorus dopant introduced the compressive stress in the films. The thin oxidized layer formed at the interface was an important factor governing the stress gradient in the multi-stacked film. This interface effect could be minimized using symmetrical stacking of polysilicon films and resulted in a low stress gradient of -0.15 MPa µm-1 for a 5.3 µm thick polysilicon layer. In single crystalline silicon, the phosphorus dopant induced the tensile stress. The lattice dilation coefficient of 4.5 × 10-24 cm3 for phosphorus was measured using a high-resolution x-ray rocking curve. A stress model was introduced on the basis of the lattice dilation theory to calculate the stress and stress gradient induced by the dopant.