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

Multilayer lithography is used for advanced semiconductor processes to pattern complex structures. As more and more procedures incorporate a high-temperature process, such as chemical vapor deposition (CVD), the need for thermally stable materials increases. For certain applications, a spin-on carbon (SOC) layer under the CVD layer is required to survive through a high-temperature process. Additionally, these materials are sometimes desired to planarize the underlying topography. Designing organic films that have high-temperature stability while also allowing for good planarization is a challenge. Rigid polymers are typically very stable, but planarizing materials are normally highly flexible, so the trade-off between properties has to be carefully designed. The materials presented in this paper are stable up to 500°C, soluble in the solvents commonly used in the semiconductor industry, provide void-free fill in high-aspect trenches, and have excellent planarization properties. The coated film has very low shrinkage through the bake temperature and is stable at high-temperature conditions. The planarization on topography in the range from local distance (a few microns), to global distance (a few hundred microns) is equivalent to our best low-temperature SOC.