This study reveals that the stoichiometricity of silicon nitride thin films (SiNx-TFs) significantly governs the packing density and water vapor transmission rate (WVTR), and it can be controlled by chemical reactions accompanied by the removal of oxygen impurities with a nitrogen neutral beam (N-NB). Here, oxygen contents of SiNx-TFs are reduced through the formation of volatile NOx, and their amount is dominated by the energy of the N-NB reflected from a negatively biased reflector (0 to −60 V). The single-layered stoichiometric SiNx-TFs with a thickness of 100 nm provides the WVTR of 6.2 × 10−6 g/(m2day), with a density and composition ratio of N/Si stoichiometry at 3.13 g/cm3 and 1.33, respectively. This optimized SiNx-TF encapsulated top-emission organic light-emitting diode has reliability under harsh condition (85 °C and 85% relative humidity) for 830 h or more.

A polydimethylsiloxane (PDMS) film is the most widely used elastomeric substrate for stretchable electronic devices. However, it is difficult to directly deposit a metal layer on the PDMS film because many defects such as cracks and wrinkles in the metal layer form too easily. This problem can be addressed by modifying the film surface rigidly through some surface oxidation processes. However, this rigid surface should be removed after the fabrication process is completed because the surface may induce lots of cracks on the PDMS film when the fabricated stretchable electronic device is used in a stretching state. In this study, a wet etching process using a buffered HF (BHF) solution is used to effectively remove the rigid surfaceformed on the PDMS film and to dramatically reduce the crack lines formed after the PDMS film stretching.Hence, areversible process for controlling the mechanical properties of the PDMS film surface was established. According tosome analysis results, the rigid surface formed by UV ozone exposure on the PDMS film was found to have apolysiloxane network structure including more silicon atoms bound to three oxygens, and the surface etched by BHFsolution was found to be recovered to the similar structure with that of the PDMS film. K E Y W O R D Sbuffered HF solution etching, polydimethylsiloxane (PDMS) film, stretchable display, reversible surface modification, UV ozone exposure

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