Growth stress induced tunability of dielectric permittivity in thin films

Abstract

Stress is inevitable during thin film growth. It is demonstrated here that the growth stress has a significant effect on the dielectric constant of high-k thin films. ZrO2 thin films were deposited on Ge by reactive direct current sputtering. Stress in these films was measured using in-situ curvature measurement tool. The growth stress was tuned from −2.8 to 0.1 GPa by controlling deposition rate. Dielectric permittivity of ZrO2 depends on temperature, phase, and stress. The correct combination of parameters—phase, texture, and stress—is shown to yield films with an equivalent oxide thickness of 8 Å. Growth stresses are shown to affect the dielectric constant both directly by affecting lattice parameter and indirectly through the effect on phase stability of ZrO2.