Novel EUV resist materials design for 14nm half pitch and below

Self Cite

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.

Section: Efficient Nti Developer Designsupporting

confidence: 64%

“…In previous work, we revealed that nBA had a clear advantage on dissolution unit grains size and surface smoothness compared to aqueous 2.38% TMAH solution [20]. Similarly, we demonstrated LWR advantage of nBA when exposing conventional polarity switch photoresist with 45 nm hp L/S [20].…”

Section: Efficient Nti Developer Designmentioning

confidence: 93%

Negative-tone Imaging with EUV Exposure

Tsubaki

Nihashi

Tsuchihashi

et al. 2015

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“…We have previously reported that combination of a high Tg and low Ea polymer with a large acid provides an apparently better L/S resolution with maintaining sensitivity [10,24]. In this study, we explored the same idea to determine how acid diffusion length contributes to block mask and isolated dot resolution.…”

Section: Influence Of Acid Diffusion Lengthmentioning

confidence: 99%

Negative-tone Imaging with EUV Exposure toward 13 nm hp

Tsubaki

Nihashi

Tsuchihashi

et al. 2016

Self Cite

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.

“…While sensitivity became slightly worse, the total resist performance turned out improved, judged from the Z-factor [3]. Tsubaki et al investigated the dependency of pinching behavior of 15-18 nm HP with low activation energy (Ea) polymer, revealing that pinching was suppressed when the polymer Tg was 40 o C and over higher than the post exposure bake (PEB) temperature [4]. From the chemical structural point of view, methacrylic terpolymers containing various adamantyl polar units were compared by Tanagi et al showing that unit with long alkyl connecting group and two hydroxyl groups gave good resist performance in terms of resolution and line edge roughness (LER) by EB lithography test.…”

Section: Pag Blend Type 211 Polymer Developmentmentioning

confidence: 99%

Recent EUV Resists toward High Volume Manufacturing

Nakagawa¹,

Naruoka²,

Nagai³

2014

Extreme ultraviolet lithography (EUVL) has been an attractive method as next generation lithography (NGL) over 20 years, and high-volume manufacturing (HVM) is now going to be realized by great progresses in materials as well as EUV source power enhancement. In this paper, recent reported materials for EUVL are summarized ranging from conventional organic material base resists to novel inorganic material base resists.