Development of planarizing spin-on carbon material for high-temperature processes

Abstract

For the last several advanced semiconductor nodes, as the industry moves towards 7- and 5-nm processes, the requirements for patterning and image transfer have increased dramatically. Multilayer material stacks are needed to pattern complex high-resolution structures. For carbon films, one key point is the tradeoff between planarization and high-temperature stability requirements used in patterning and post-patterning process integration. On one side, the need for thermally stable carbon materials is steadily increasing, for better pattern transfer fidelity (less line wiggling), chemical vapor deposition (CVD) compatibility where a plasma-enhanced CVD (PECVD) inorganic hardmask is deposited on top, and for the use as mandrels for pattern multiplication. On the other hand, due to the increased complexity of chip designs, gap filling and planarization of the underlying topography is also strongly desired. In addition, wet chemical resistance and the capability to be polished by chemical mechanical planarization (CMP) processes are often necessary. Design of a spin-on carbon (SOC) film to meet all the desired, but sometimes conflicting, properties using organic polymers with good solubility in fab-approved solvent systems requires innovative chemical design and rigorous experiment and tuning processes. Brewer Science's advanced material development is bringing forth low-shrinkage, high-temperature-stable SOCs with spin-bowl/drain compatibility for advanced node manufacturing and integration. The materials presented in this paper are stable up to 500-550°C with no weight loss, soluble in solvents commonly used in semiconductor industry, can fill 2 µm thickness, which has showed early promising results in filling some very-high-aspect-ratio gaps in certain memory applications.