Unusual 1,1-Dicarboxylation Selectivity in the DominoHydrocarboxylation of Alkynes with Formate and Applicationin Polyimide Photoresists

The fundamental principle of photolithography is that the crosslinking or degradation reaction of the photoresist causes a significant change in solubility. Traditional positive photoresists currently rely on the photoinduced decomposition of diazonaphthoquinone sulfonate (DNQ) or the deprotection of tert-butoxycarbonyl (Boc) groups to release carboxyl groups. However, there are several issues associated with these approaches: 1. DNQ is used in large quantities (25%) and is not heat-resistant; 2. Acid diffusion leads to increased line-edge roughness. To address these issues, we have developed a photoinduced alkyne domino 1,1-dicarboxylation reaction and applied this method to the working mechanism of positive photosensitive polyimide photoresists. This method can directly prepare water-soluble carboxyl-functionalized molecules and polymers from hydrophobic alkyne precursors. In this work, we synthesized five different types of photosensitive polyimides, all of which exhibited significant changes in solubility before and after exposure. Notably, this photochemical reaction is carried out under alkaline conditions, which can avoid acid corrosion that may affect the quality of the lithographic patterns.Moreover, under thermal treatment conditions, the residual alkyne groups can undergo crosslinking reactions, making the photoresist film more stable and providing better mechanical properties. This demonstrates the potential application value of our method in semiconductor manufacturing lithography technology. This research is of great significance.