Ta₂O₅薄膜の結晶化に伴う機械的性質の変化

抄録

With the increasing level of integration in semiconductor devices, Ta₂O₅ thin film is attracting much interest for use in the capacitors of semiconductor memory devices because of its high dielectric constant. In the fabrication process of the device, the Ta₂O₅ thin film is deposited in the amorphous condition and then crystallized by annealing. In order to increase the mechanical reliability of the capacitors, the change in mechnical properties of the Ta₂O₅ film during crystallization must be determined. The Young's modulus was therefore measured by the three-point bending method, and residual stress and thermal expansion coefficient were calculated by measuring the curvature of a substrate with the Ta₂O₅ film. It was found that the crystallization increases the residual stress of the film from 250 to 400 MPa and the Young's modulus from 130 to 180 GPa.And the thermal expansion coefficient is decreased from 5.7×10^-6 to 3.6×10^-6.