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24 December 2015 Platinum and palladium oxalates: positive-tone extreme ultraviolet resists
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Here, we present platinum and palladium mononuclear complexes with EUV photosensitivity and lithographic performance. Many platinum and palladium complexes show little or no EUV sensitivity; however, we have found that metal carbonates and metal oxalates (L2M(CO3) and L2M(C2O4); M=Pt or Pd) are sensitive to EUV. The metal carbonates give negative-tone behavior. The most interesting result is that the metal oxalates give the first positive-tone EUV resists based on mononuclear organometallic compounds. In particular, (dppm)Pd(C2O4) (dppm=1,1-bis(diphenylphosphino)methane) (23) prints 30-nm dense lines with Esize of 50  mJ/cm2. Derivatives of (23) were synthesized to explore the relationship between the core metal and the resist sensitivity. The study showed that palladium-based resists are more sensitive than platinum-based resists. The photoreaction has been investigated for two of our most promising resists, (dppm)Pd(C2O4) (23) and (Ph2EtP)2PdC2O4 (27). Our experiments suggest the loss of CO2 and the formation of a zerovalent L4Pd complex upon exposure to light. We have identified dppm2Pd(δ(P)23.6) as the main photoproduct for (23) and (Ph2EtP)4Pd (δ(P)32.7) as the main photoproduct for (27).
Miriam Sortland, Jodi Hotalen, Ryan Del Re, James Passarelli, Michael Murphy, Tero S. Kulmala, Yasin Ekinci, Mark Neisser, Daniel A. Freedman, and Robert L. Brainard "Platinum and palladium oxalates: positive-tone extreme ultraviolet resists," Journal of Micro/Nanolithography, MEMS, and MOEMS 14(4), 043511 (24 December 2015).
Published: 24 December 2015

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