Alternative developer solution/process for EUV lithography: ethyltrimethylammonium hydroxide (ETMAH)

The application of the ethyltrimethylammonium hydroxide (ETMAH) as alternative developer solution for EUV lithography was investigated (compared to the tetramethylammonium hydroxide or TMAH standard developer). Early reports have shown that at a specific or optimal developer concentration of around 0.20N the ETMAH developer allows mitigation of resist-based stochastic defects (increase in stochastic defect margin) while maintaining lithographic performance. Results obtained here suggest that with the use of a non-ionic surfactant additive for the ETMAH developer solution LWR reduction was achieved (compared to TMAH). This improvement in LWR was achieved while preserving resolution, sensitivity, and stochastic defect margin.