Fabrication of low temperature SOC/SiO₂ with low surface roughness for advanced nodes manufacturing

The critical dimensions (CD) continue to shrink as fabrication node advances, imposing increasingly stringent requirements on thin-film deposition, lithography, and etch transfer processes. Traditional hard mask material such as silicon dioxide (SiO₂) is now facing significant challenges due to its poor compatibility with the widely adopted spin-on carbon (SOC)/bottom anti-reflective coating (BARC) hard mask system. Here we report a low temperature plasma enhanced chemical vapor deposition (PECVD) technique that allows directly growing SiO₂ on top of SOC. Notably, the SiO₂ layer is fabricated using an optimized two-step process to prevent damage to the underlying SOC. Further results suggests that an etch-back process is beneficial to establish lower surface roughness. The superior surface properties of the bilayer structure may provide robust foundations for subsequent lithography process, and offer novel insights for future hard mask design.