Enhanced mechanical properties of the high-resolution EUVL patterns of hybrid photoresists containing hexafluoroantimonate

• Published in: Microelectronic engineering 2018-07, Vol.194, p.100-108
• Main Authors: Kumar, Pawan, Reddy, Pulikanti Guruprasad, Sharma, Satinder K., Ghosh, Subrata, Pradeep, Chullikkattil P., Gonsalves, Kenneth E.
• Format: Article
• Language: English
• Subjects: Adhesion; Aspect ratio; Collapse; Composition; Dependence; Elbow (anatomy); Extreme ultraviolet (EUV) lithography; High resolution; Low activation energy; Low temperature physics; Mechanical properties; Modulus; Next generation lithography; Novel nonchemically negative tone (n–CARs) resists; Offset printing; Optimum dose; Patterning; Patterns collapse; Photoresists; Sub 20 nm technology node; Ultraviolet radiation
• ISSN: 0167-9317; 1873-5568
• DOI: 10.1016/j.mee.2018.03.014

The present study investigates the mechanical properties of hybrid photoresists in the context of their pattern-collapse behaviors. The mechanical properties such as the DMT (Derjaguin, Muller, Toropov) modulus and tip-sample adhesion forces of the high-resolution patterns obtained from two hybrid EUV photo-resists, 1.5% & 2.15%-MAPDSA-MAPDST bearing hexafluoroantimonate and triflate counter ion moieties have been investigated using peak force quantitative nano-mechanical mapping (PF-QNM) technique. The mechanical properties of the well resolved high-resolution 90–20 nm (L/5S) line patterns, 20–32 nm (L/2S-L/5S) lines patterns and nano-features such as line-elbow connections have been investigated and analyzed against the differences in their SbF6− composition. For the 1.5%- MAPDSA-MAPDST resist case the DMT modulus and tip-sample adhesion forces are found strong dependence on the resist line width and line spacing, as compared to 2.15%- MAPDSA-MAPDST resist. There is a significant improvement in the modulus value of 5 GPa for 2.15%-MAPDSA-MAPDST resist in contrary to the ~2.7 GPa for the 1.5%-MAPDSA-MAPDST resist for the 20 nm (L/2S) Line patterns. Similarly, the tip sample adhesion forces on resist surface are also found dependent on patterns aspect ratio as well as on SbF6− content in the resist composition. These studies revealed that an increase of the SbF6− content in the resist formulation, imparts cascading effects to the mechanical properties of their high-resolution nanopatterns, which in turns helps to reduce the pattern collapse resulting in superior patterning performances. [Display omitted] •The EUVL performance of MAPDSA-MAPDST resist is studied.•The patterns collapse mechanism for EUVL resist by PF-QNM technique.•The resist modulus dependence on resist lines width/separation•The SbF6 content has a significant effect on the resist sensitivity.•The SbF6 addition results in collapse free EUV resist pattern.