Sudip Mukhopadhyay

A high-Si content middle layer for ArF trilayer patterning

This work discusses the development and characterization of Honeywells middle layer material, UVAS, for trilayer patterning. The UVAS polymer contains high Si content constructed by polymerizing multiple monomers selected to produce a film that meets the requirements as a middle layer for trilayer patterning. Results of ArF photoresist patterning evaluations, plasma and wet etch studies, and photoresist and full stack rework tests will be presented and discussed. ArF photoresist patterning tests show that UVAS exhibits organic BARC like performance with respect to MEEF (Mask Error Enhancement Factor), DOF (Depth of Focus) and EL (Exposure Latitude). Shelf life data shows that UVAS maintains very stable properties even after 6 months storage at room temperature. We will also briefly discuss investigation of amine or nitrogen-based contaminant blocking by the UVAS middle layer.

Next generation siloxane-based Bottom Anti-Reflective Coating (BARC) formulations with selective strip rates and required optical properties

Bottom Anti Reflective Coating (BARC) materials are generally used to minimize reflection of incident light from the substrate (Rsub). As IC manufactures move to high NA systems to meet the patterning requirements for next generation technology as well as the use of new lower dielectric constant materials in the back-end-of-line dielectric, the requirements for developing BARC materials with new properties such as faster strip rate and properly tuned optical properties (n = refractive index and k=extinction coefficient) are essential. Some photoresist patterning schemes may also require a dual BARC system such as tri-layer patterning (TLP), which is undergoing extensive evaluation in academia and industries. This work focuses on Honeywells next generation DUO193 material (DUO193FS), which is a siloxane-based polymer with an organic 193 nm chromophore attached to it. The effects of additives for adjusting strip rate in a wet chemical stripper, while maintaining chemical resistance to a photoresist developer, 2.38% TMAH in water are discussed. Different spectroscopic studies are performed to elucidate the mechanism of faster strip rate. Solvation of silanol groups and their orientation in the presence of additives are found to be secondary mechanism. The primary reason for enhanced strip rate is attributed to the addition of additives A and B, which lower bulk density of the solid film. DUO193FS can be stand alone BARC or used with another BARC as part of a dual BARC system to further minimize Rsub, maintaining resistance to 2.38% TMAH, planarizing any underlying topography and keeping the final film strip rate high.