Liquid crystalline donor (i.e., phthalocyanine) was covalently linked to acceptor (i.e, fullerene) to achieve efficient charge-transport properties in a liquid crystalline phase. The columnar structure exhibited highly efficient ambipolar charge-transport character, demonstrating the potential utility of the strategy in organic electronics.

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Negative-tone imaging (NTI) with EUV exposure has major advantages with respect to line-width roughness (LWR) and resolution due in part to polymer swelling and favorable dissolution mechanics. In NTI process, both resist and organic solvents play important roles in determining lithography performances. The present study describes novel chemically amplified resist materials based on NTI technology with EUV using specific organic solvents. Lithographic performances of NTI process were described in this paper under exposures using ASML NXE:3300 EUV scanner at imec. It is emphasized that 14 nm hp was nicely resolved under exposure dose of 37 mJ/cm 2 without any bridge and collapse, which are attributed to the low swelling character of NTI process. Although 13 nm hp resolution was potentially obtained, a pattern collapse still restricts its resolution in case coating resist film thickness is 40 nm. Dark mask limitation due mainly to mask defectivity issue makes NTI with EUV favorable approach for printing block mask to produce logic circuit. A good resolution of CD-X 21 nm/CD-Y 32 nm was obtained for block mask pattern using NTI with usable process window and dose of 49 mJ/cm 2 . Minimum resolution now reaches CD-X 17 nm / CD-Y 23 nm for the block. A 21 nm block mask resolution was not affected by exposure dose and explored toward low dose down to 18 mJ/cm 2 by reducing quencher loading. In addition, there was a negligible amount of increase in LCDU for isolated dot pattern when decreasing exposure dose from 66 mJ/cm 2 to 24 mJ/cm 2 . On the other hand, there appeared tradeoff relationship between LCDU and dose for dense dot pattern, indicating photon-shot noise restriction, but strong dependency on patterning features. Design to improve acid generation efficiency was described based on acid generation mechanism in traditional chemically amplified materials which contains photoacid generator (PAG) and polymer. Conventional EUV absorber which comprises of organic compounds is expected to have 1.6 times higher EUV absorption than polyhydroxystyrene based on calculation. However, observed value of acid amount was comparable or significantly worse than polyhydroxystyrene.

The advantages of NTI process in EUV is demonstrated by optical simulation method for 0.25NA and 0.33NA illumination system with view point of optical aerial image quality and photon density. The extendablity of NTI for higher NA system is considered for further tight pitch and small size contact hole imaging capability. Process and material design strategy to NTI were discussed with consideration on comparison to ArF NTI process and materials, and challenges in EUV materials dedicated to NTI process were discussed as well. A new polymer was well designed for EUV-NTD process, and the resists formulated with the new polymer demonstrated good advantage of resolution and sensitivity in isolated trench imaging, and 24 nm half pitch resolution at dense C/H, with 0.3NA MET tool.

Manipulation of dissolution properties by changing organic solvent developer and rinse material provides a novel technology to obtain fine pattern beyond the limitation of imaging system based on alkaline developer. QCM study showed no swelling character in negative-tone imaging (NTI) process even for current developer of n-butyl acetate (nBA). Actually, NTI process has shown advantages on resolution and line-width roughness (LWR) in loose pitch around 30 ~ 45 nm hp as a consequence of its non-swelling character. On the other hand, bridge and collapse limited its resolution below 20 nm hp, indicating that non-negligible amount of swelling still exists for tight pitch resolution. We investigated effects of solubility parameter of organic solvents on resolution below 20 nm hp. A bridge was reduced with a decrease in the solubility parameter p from nBA. On the other hand, much lower p caused film remaining due to its extremely slow Rmax. Based on these results, we newly developed FN-DP301 containing organic solvent with smaller p than nBA. Although rinse solvent gave negligible effects on bridge, there is a clear improvement on pattern collapse only in case of using new rinse solvent of FN-RP311.Lithographic performances of NTI process using nBA and FN-DP301 together with the other organic solvents were described in this paper under exposures with an E-beam and a EUV light. It is emphasized that 14 nm hp resolution was obtained only using FN-DP301 as a developer and FN-RP311 as a rinse under E-beam exposure. NTI showed 43% faster photospeed in comparison with PTI at 16 nm hp, indicating that NTI is applicable to obtain high throughput with maintaining resolution. In addition, sub-20 nm trench was obtained using NTI without bridge under EUV exposure, all of which are attributed to the low swelling character of NTI process. Similarly, NTI was able to print 20 nm dots using NXE:3100 with only a little peeling. Conversely CH patterning was significantly worse with NTI compared to PTI, that is, only 36 nm contacts with 60 nm pitch was resolved under EUV exposure.