In this report, we will describe the progress of our new SOC material development for the underlayer. In the advanced patterning technology such as EUV lithography, the etching resistance and the adhesive property with a middle layer will be key requirements as well as the planarization. We designed new polymers for SOC material that were improved the etching resistance toward next generation patterning technology on the basis of Ohnishi parameter as a guideline of the polymer design. The etching resistance of our newly developed polymers were about 1.7 times and 1.5 times stronger than the polymer A we reported previously and the PHS or novolac. The adhesive property was evaluated by measuring water contact angle and the water contact angle of our newly developed polymers were similar to the novolac. This result indicated that the developed polymer showed similar hydrophilicity to the novolac with keeping higher O<sub>2</sub> etching resistance than novolac.
As advancement of semiconductor to 1Xnm nodes and beyond, the importance of multilayer lithography process is increasing. Generally, multilayer consists of photoresist layer, middle layer and underlayer. Theses layer materials prefer spin-on type to CVD type from the viewpoint of the cost of ownership and process simplicity. The key requirements which spin-on materials must satisfy are to be soluble in organic solvent and insoluble after bake process to coat upper layer materials, gap filling and planarization performances, etch controllability and easy strippability. In particular, the solubility switchable property, the gap filling and planarization performance on topo-patterned substrate are receiving much attention recently. In this report, novel spin-on carbon (SOC) material for multilayer lithography process will be described. The SOC materials we present here consist of the thermoplastic polymer which we originally developed and PGMEA or cyclohexanone as solvent, there is no any other additive. This varnish can be applied to a substrate by spin-on coating. It is worth noting that the SOC layer after bake process becomes insolubilized for PGMEA. This property enables to use PGMEA when stacking upper layer. Because of the intrinsic thermal flow nature of our thermoplastic polymer, the gap filling and planarization performances are excellent for the topo-patterned substrate which includes pad, open and dense line area. The etch rate of the SOC layer for C<sub>x</sub>F<sub>y</sub> gas is constant, so these materials have good etch controllability. Therefore, these SOC materials could be potentially candidate for planarization use in multilayer lithography process.