Abstract
The viscoelastic behavior of SiO2 in the system Si/SiO2 during isothermal heat treatment is studied by directly imaging the x‐ray topography contrast due to lattice strains at oxide edges of test structures. We measure the relaxation time of those strains, e.g., the time to reach zero x‐ray contrast, at different temperatures above 900 °C, the minimum temperature for plastic deformation of SiO2. An Arrhenius plot of the relaxation time yields activation energies for viscous flow of 4.3 for normal‐ and 2.3 eV for high‐pressure thermal SiO2. For small rectangular oxide windows we find the relaxation time proportional to the square root of the window area.