Advanced developer-soluble gap-fill materials and applications

For the via-first dual damascene process, a planarizing anti-reflective material and gap-fill material are typically used to ensure a lithography process produces the best profiles and critical dimension (CD) control and integrates structures having small feature sizes. Traditionally a gap-fill material is usually coated in a thick layer, and then plasma etching is used to remove the extra gap-fill material above the substrate surface. We have developed a unique developer-soluble gap-fill material, BSI.G05013, which can be etched back in standard photoresist developer, instead of by plasma beam irradiation. By careful design of both the polymer and the formulation, our developer-soluble gap-fill materials fill vias and trenches on different substrates without void formation. Also, these gap-fill materials do not exhibit swelling or peeling problems during the developer etch-back process. Dissolution rate is adjustable by customizing the material with regard to the chemical structure of the polymer and the formulation composition. This new generation of developer-soluble gap-fill material has broad process windows for bake temperature and develop time. The local bias between dense and isolated via areas and the global bias from wafer center to wafer edge are significantly reduced after develop back due to the dissolution rate difference between the bulk material and the material inside of the vias. Material is spin bowl compatible and does not precipitate in rinsing solvents. It is stable in storage conditions for a long period. Both dry plasma cleaning and wet developer cleaning can be used to remove the residual gap-fill material after processing. This new generation of develop-soluble gap-fill material, BSI.G05013 is robust and the process is economically favorable, which makes this solution convenient for planarizing surfaces.