Investigation for the structural stress of SiO2 thin films and its distribution on the large-wafer created by plasma enhanced chemical vapor deposition

Abstract

For a multilayered configuration of SiO2 film created by plasma enhanced chemical vapor deposition (PECVD), the thermal stress and growth-caused stress are two intrinsic stresses. In this work, based on the interactions of all the layers of film, a nonlinearly distributed structural stress over a large substrate is found. The numerical simulations for the nonlinear distribution of the structural stress and the uniform distributions of the two intrinsic stresses are carried out. As a result, the tensile structural stress decreases by ∼4x105MPa from center to edge of a 6” silicon wafer and the compressive growth-caused stress increases by ∼5x105MPa corresponding to the growth-rate increase of 40nm/s, which matches a ∼120MPa distribution of residual compressive stress obtained with in-situ measurements of film samples. In simulations, it is also discovered that the initial curvature of substrate has an impressive influence on the later grown film.