SiO₂ Deposition at Low Temperature Using PECVD for Application to Plastic Substrates

Abstract

This study investigates the low-temperature deposition of SiO₂ films using plasma-enhanced chemical vapor deposition (PECVD) for flexible electronics applications, focusing on heat-sensitive substrates, such as polyethylene terephthalate (PET). We compared SiO₂ films deposited at 400 kHz and 13.56 MHz plasma excitation frequencies using tetraethyl orthosilicate (TEOS) as the precursor. Films were characterized for deposition rate, refractive index, stress, density, and surface morphology. Si substrate was used for evaluation. Results exhibit that 400 kHz deposition yields enhanced film properties compared to 13.56 MHz, exhibiting higher deposition rates, increased refractive index (up to 1.475), compressive stress, and slightly higher density, while maintaining smooth surfaces. These improvements are attributed to intensified ion bombardment effects in the low-frequency plasma. The 400 kHz PECVD process demonstrates potential for fabricating high-quality dielectric and passivation layers in flexible electronic devices at temperatures below 60°C, addressing the critical need for low-temperature processes in next-generation flexible electronics development.