193 nm Resist Line Collapse Study by Modifying the Resist Polymer and Process Conditions with Utilizing FIRM Process

Device design rules are continuously shrinking toward the optical resolution limit of k1 factors below 0.3. The requirements for 193 nm photoresist below 90 nm node manufacturing are quite challenging. Using a DI water rinse after development gives a significant amount of line collapse when the aspect ratio is over 3. To avoid line collapse, Tokyo Electron co-developed a special rinse solution for the FIRM process with Clariant Japan K.K. Utilizing FIRM process, 90 nm dense line collapse was measured by CD SEM using focus-exposure matrices. Line collapse in experimental 193 nm positive tone resists was studied by varying monomer ratios of the polymer and process conditions. The surface properties of the resist were also studied to investigate the interaction with the rinse solution in the de-protected region. However, a high surfactant concentration in the DI water rinse can lead to swelling of the resist pattern profile. It is important to co-optimize the resist component and the adequate surfactant concentration in the rinse solution to minimize line collapse and pattern deformation. Both δP and σmax were calculated along the FEM to investigate line collapse dependence on the resist hydrophobicity.