Research of mask photoresist sensitivity for local critical dimension uniformity improvement in ArF lithography

With the continuous development of advanced semiconductor technology, the critical pattern shrinkage stably in integrated circuits has become a crucial step for product performance improvement and power consumption reduction. Compared with EUV technology, ArF immersion lithography of DUV is still the most popular research for advanced wafer fabrication, which makes the local critical dimension uniformity (LCDU) improvement become challenging for continuous pattern shrinkag. In the known research, LCDU for small hole pattern is affected by various factors, such as MEEF/OPC model/pattern density on mask and litho/Etch/Metrology process and so on. In the previous study, the improvement of wafer LCDU could be achieved by reducing MEEF of using HT PSM mask. On this basis, we also studied a new type of low sensitivity photoresist for HT PSM mask, which has better performance in controlling LER and LWR. In the meantime, compared with the actual performance of mask LCDU, it is verified that this new photoresist has obvious improvement. This paper mainly studies and compares the differences between the new low sensitivity photoresist and traditional photoresist, and conducts experiments to verify its performance on mask LCDU with extreme small hole patterns. It was found that the LCDU of the mask using new photoresist is improved by ~12%. Furthermore, in the actual application of fab production, the wafer LCDU is improved about 6~10%, and the pattern resolution and profile have also been improved to some extent, this research has played an important role in the development of advanced semiconductor processes.