Challenges for immersion lithography extension based on negative tone imaging (NTI) process

Negative tone imaging (NTI) is a method for obtaining a negative-tone reversal pattern by developing with an organic solvent. As NTI process can break-through the resolution limit of a conventional positive-tone development (PTD) process, it has been applied for mass production in 20nm and 14 nm nodes device. In this paper, we examined the possibility of a bi-layer process using novel Si-containing NTI resist. As a results, the resolution of the Si-NTI resist achieved comparable level to a conventional NTI resist with a strong etching resistance. It is very effective for process cost reduction.