Study on planarization performance of spin on hardmask

For multilayer process, the importance of spin on carbon (SOC) material that replaces amorphous carbon layer (ACL) is ever increasing. SOC is an organic polymer with high carbon content formulated in organic solvents for spin-coating application that is cured through baking. In comparison to ACL which is applied by CVD process, SOC material can offer several benefits: lower cost of ownership (CoO) and shorter process time as well as better gap-fill and planarization performances. Thus SOC material of high etch resistance, good gap-fill properties, and global planarization performances over various pattern topographies is desired to achieve fine patterning with high aspect ratio (A/R). In particular, good level of global planarization of spin coated layer over the underlying pattern topographies is important for self-aligned double patterning (SADP) process as it dictates the photolithographic margin. Herein, we report a copolymer SOC resin formulation that exhibits favorable film shrinkage profile and ideal etch resistance properties. By combining the favorable characteristics of each resin — one resin with good shrinkage property and the other with excellent etch resistance into the copolymer, it was possible to achieve desirable level of etch resistance and planarization performances across various pattern topographies of underlying substrate.