Selection of ESH solvents for the wet removal of post-etch photoresists in low-k dielectrics integration

All-wet processes are gaining a renewed interest for the removal of post-etch photoresist (PR) in semiconductor manufacturing. However, changes in regulations call for a reduction in the environmental, safety & health (ESH) impact of solvents used. In this work, 9 solvents and about 50 solvent mixtures were evaluated as to their efficiency in dissolving two DUV (193nm) PR. Selection was performed according to a set of ESH criteria and to solubility properties, as characterized by Hansen solubility parameters (HSP). Most solvents and mixtures were found to dissolve both PR materials in a reasonable time (=<10min) at room temperature, with best solvents requiring less than 30s. The surprisingly large domain of good solvents in Hansen plots was tentatively attributed to the copolymer character of the PR, in similitude to the swelling behavior of copolymers. Differences in dissolution kinetics were not correlated to HSP and are discussed in terms of solvent molecular size and PR copolymer character.