Mechanistic insights of Sn-based non-chemically-amplified resists under EUV irradiation

• Published in: Applied surface science 2020-12, Vol.533, p.146553, Article 146553
• Main Authors: Belmonte, Guilherme K., Cendron, Suelen W., Guruprasad Reddy, Pulikanti, Moura, Cleverson A.S., Ghulam Moinuddin, Mohamad, Peter, Jerome, Sharma, Satinder K., Albara Lando, Gabriela, Puiatti, Marcelo, Gonsalves, Kenneth E., Weibel, Daniel E.
• Format: Article
• Language: English
• Subjects: EUVL; n-CAR; NEXAFS; Photofragmentation Mechanism; Sn- hybrid; XPS
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.146553

[Display omitted] •Organotin resist showed ~ 12–15 nm lithographic resolution by e- and He+ irradiation.•Rearrangements and SnO2 after EUV irradiation were detected by XPS and NEXAFS.•FEFF9 theoretical calculations confirmed NEXAFS data and gives clues on the mechanism.•The presence of Sn covalent linked to the main polymer structure is highlighted. Formulating high sensitivity and resolution in Extreme Ultraviolet (EUV) resists is a serious concern regarding the adaptation of EUV lithography. The incorporation of a high optical density Sn compound in MAPDST-co-ADSM (4-(methacryloyloxy)phenyl) dimethylsulfoniumtrifluoromethane sulfonate-co-acetyldibutylstannyl methacrylate, a non-CAR photoresist, exhibits lithography resolution for sub-15 nm node when patterned under e-beam and Helium ion irradiation. The synthesized resists were irradiated at 103.5 eV (~92 eV) using monochromatic synchrotron radiation. After EUV irradiation and oxidation, the resists were investigated using XPS, NEXAFS and by theoretical calculations (FEFF9 modeling program). It was observed significant changes in the labile CF3SO3– moiety, but interestingly its total dissociation or desorption was not observed after long exposure times. Bonds rearrangements of formation of SnO2 and new S–C/C–F functionalities after irradiation were detected. Those complex processes suggested the existence of important sinks for the high photon energy absorbed, which in turn increased the lithography resolution. The present results highlight the importance of the incorporation of a heavy metal covalently linked to the main polymer structure. The enhanced resolution observed in the MAPDST-co-ADSM resist formulation using standard processing conditions, establishes its potential candidature as a EUVL resist for rapid prototyping of semiconductor devices.