Examination of possible primary mechanisms for 193nm resist shrinkage

Lior Akerman; Guy Eytan; Ryusuke Uchida; Satoshi Fujimura; Takeyoshi Mimura

doi:10.1117/12.599934

10 May 2005 Examination of possible primary mechanisms for 193nm resist shrinkage

Lior Akerman, Guy Eytan, Ryusuke Uchida, Satoshi Fujimura, Takeyoshi Mimura

Proceedings Volume 5752, Metrology, Inspection, and Process Control for Microlithography XIX; (2005) https://doi.org/10.1117/12.599934
Event: Microlithography 2005, 2005, San Jose, California, United States

Abstract

As the need to create smaller features increases, the industry is moving on to 193nm photoresist systems. It is well known that one problem with this resist is its shrinkage under secondary electron microscope (SEM) measurements. While different phenomena arising from electron-material interaction are assumed to take place (such as crosslinking and scission), the primary mechanism which brings about this shrinkage is still unclear. This paper comprises four main experiments, relating to four theories for the primary mechanism which brings about the shrinkage. In the first experiment we wanted to examine how the shrinkage is affected by subjecting the resist to 193nm exposure (after patterning). This experiment examines the theory that the electron exposure induces an effect similar to that of 193nm exposure. The second experiment deals with e-beam curing in different doses, using working parameters similar to those used in SEM measurements (e-beam curing entails a much smaller power density than SEM measurements). The third experiment addresses the theory of disassociation of carbonyl bonds in the resist, leading to crosslinking and eventual evaporation of CO2 molecules. The last experiment tests the theory that the shrinkage is caused by the collapse of voids within the photoresist, generated during the resist coating or subsequent bakes. From the results we conclude that an effect similar to radiation exposure, local heating and the collapse of voids are not likely candidates for the primary mechanism. We did, however, find a correlation between the carbonyl levels in the resist and the shrinkage.

Citation Download Citation

Lior Akerman, Guy Eytan, Ryusuke Uchida, Satoshi Fujimura, and Takeyoshi Mimura "Examination of possible primary mechanisms for 193nm resist shrinkage", Proc. SPIE 5752, Metrology, Inspection, and Process Control for Microlithography XIX, (10 May 2005); https://doi.org/10.1117/12.599934

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