Enhancing photoresist performance with an adhesion promoting photo-acid generator

Abstract

Concentration gradients of photoacid generator through the thickness of the photoresist film can profoundly affect the material's performance. To engineer the acid concentration through resist thickness, we have developed a new type of resist adhesion promoting layer that incorporates photo acid generator chemistry. These adhesion promoting photo acid generators, called as a class enhance acid concentration at interface between the resist and the substrate. We will provide an overview on the preparation and characterization of two siloxane based APPAG materials along with a performance comparison of commercial DUV, EUV and E-beam photoresists on APPAG. Nonaflate analog (APPAG 6) with shorter acid diffusion length was found to have a mild impact on 250nm node DUV lithography. However the triflate analog (APPAG 9), owing to the larger acid diffusion length, was shown to provide a greater influence. APPAG 9 was found to give nearly a 50% improvement in depth of focus. For EUV lithography, both APPAG 6 and APPAG 9 will be shown to substantially improve performance envelope for 100nm dense lines and spaces and at reduced post exposure bake (PEB) temperatures. This indicates that this approach can be used to gain margin at reduced PEB which is desirable to minimize thermally driven diffusion effects. Thus the materials represent an important new approach to extending photoresist performance margins.