Dielectric Constant and Stability of Fluorine‐Doped Plasma Enhanced Chemical Vapor Deposited SiO2 Thin Films

Abstract

As device geometry shrinks to 0.35 μm and below, the parasitic capacitance between closely spaced metal lines becomes important in terms of resistance‐capacitance time delay in device switching. In this study, we investigated the use of fluorine doped plasma enhanced chemical vapor deposition grown silicon oxide thin film as a low dielectric constant intermetal dielectric material. We evaluated and an organometallic liquid source triethoxyfluorosilane as the F dopant. It was found that the dielectric constant generally decreased as the F concentration increased. However, we also found that above a certain F concentration, the F‐doped oxide film would become unstable and absorb moisture from the ambient. At similar F concentrations, the films deposited with the liquid source are always more stable than those deposited with . This, in addition to the different stress vs. low frequency radio frequency power behavior between the two types of film, suggests that the already present Si‒F bond in the liquid precursor results in a denser and more stable film compared to the doped film where interstitial F may be present.