Investigating high opacity and increased activation energy in the multi-trigger resist

The development of novel EUV resists is widely agreed to be one of the highest priority challenges for the deployment of high-NA EUV lithography. One potential approach is the multi-trigger concept wherein a reaction will only occur when multiple elements of the resist are initiated concurrently and in close spatial proximity. The multi-trigger material presented consists of a novel MTR molecule and a crosslinker, which represent the resist matrix, together with a photoacid generator (PAG). Research is continuing to upgrade this resist, in particular focusing on improving resist opacity and crosslinking density. Here we present results from further work focused on the enhancement of the high-opacity MTR resist. A new high-Z crosslinker molecule, mark III, has been synthesized and formulated in the MTR resist to make the high opacity MTR compatible with the ethyl lactate and PGMEA casting solvents. We report results obtained using the new MTR system containing this high-Z cross-linker mark III, with a variation of process conditions and formulation variations. The lithographic performance of a formulation containing this crosslinker, at pitch 32nm patterned on an NXE3350 is presented. Furthermore, we have also investigated increasing the activation energy of the self-quenching aspect of the MTR system. In the case presented, MTR8 has a higher activation energy than MTR4. Having a higher activation energy is predicted to allow the introduction of PEB to increase crosslinking and reduce pattern collapse, whilst simultaneously preserving the self-quenching behaviour. We present results which show a decrease in dose and Z-factor using MTR8 at this formulation ratio compared to MTR4.