Surface Planarization of Low-Temperature Flowable Silicon Oxide for Atomic Layer Deposition Al₂O₃ Thin Film Encapsulation.

In this research, a flowable chemical vapor deposition (FCVD) process was developed to planarize particle-scattered surfaces for thin film encapsulation by atomic layer deposition (ALD). Nanometer-thick ALD layers are known to have good barrier properties owing to the conformal deposition of the films and their high density, but those barrier properties are vulnerable to degradation because of surface particles on the substrates. In this study, FCVD silicon oxide layer was applied to particlescattered surfaces as a planarization interlayer. Flowable silicon oxide thin films were deposited with tetrabutoxysiline and O₂ in an inductively coupled plasmas reactor. The chemical bonding structure of the flowable silicon oxide was verified with Fourier transform infrared spectroscopy. To confirm the planarization effect, particles 2 m in diameter were intentionally spread on the substrates by electrospray processing and nanometer-thick Al₂O₃ layers were deposited on top of the planarization interlayers. With the flowable silicon oxide interlayer and the same particle density on flexible substrates, the water vapor transmission rate was reduced to 1.2×10 g/(m² day) from 2.0×10 g/(m² day). The flowable silicon oxide layers are thus demonstrated to be effective interlayers to reduce the influence of particle contamination for ALD barrier films.