Application of alternative developer solutions for EUV lithography

Self Cite

Investigations were made on the application of aqueous ethyltrimethylammonium hydroxide (ETMAH) as an alternative developer solution (compared to the de facto standard aqueous tetramethylammonium hydroxide or TMAH) for mainstream lithographic technologies; extreme ultraviolet (EUV), ArF immersion (ArFi), KrF, and i-line. Results show that for EUV, ETMAH at a specific developer concentration allows mitigation of resist-based stochastic defects while maintaining lithographic performance. It was also found that the ETMAH developer solution is compatible with the ArFi, KrF, and i-line lithography (ultimate resolution and line width roughness was maintained). For EUV, ArFi, and KrF lithography which utilizes chemical amplification resist (CAR) material platforms, sensitivity remained constant. For i-line lithography, sensitivity was observed to decrease by roughly 25%–30% when ETMAH was utilized, attributed to the different dissolution mechanism of the novolac-based resist compared to CAR. Nevertheless, these results show the viability of ETMAH as an alternative developer solution for mainstream semiconductor lithography.

Section: Stochastic Defect Analysis For Euv Lithographymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of ethyltrimethylammonium hydroxide (ETMAH) as an alternative developer solution/process for semiconductor lithography

Santillan

Harumoto

Motono

et al. 2021

Self Cite

“…This emphasizes the significant role of the development process in the physical formation of stochastic defects, which underlies the consistent and continuous interest in the research of developer solutions. [23][24][25][26][27][28][29][30][31][32][33] In our previous study, also focusing on the effect of developer solutions on photoresist dissolution, we utilized three typical EUV photoresist materials [poly(4-hydroxystyrene) (PHS) type, acryl-type, and a hybrid of PHS and acryl types] 34) and investigated the effect of developer solutions on the dissolution characteristics of these photoresists using various alkyl chain lengths of tetraalkylammonium hydroxides [tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrapropylammonium hydroxide (TPAH), and tetrabutylammonium hydroxide (TBAH)]. Results showed that the dissolution behaviors of EUV photoresists depended on the developer solutions.…”

Section: Introductionmentioning

confidence: 99%

Stochastic defect generation depending on tetraalkylhydroxide aqueous developers in extreme ultraviolet lithography

Harumoto¹,

Santos²,

SANTILLAN³

et al. 2023

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Patterning targets in leading-edge technologies such as extreme ultraviolet lithography (EUVL) are starting to push present photoresist materials (e.g., chemical amplification resists) to their physical limits. The appearance of randomly occurring (stochastic) photoresist-based defects in these stringent patterning targets has become one of the main concerns in EUVL. To obtain possible clues to understanding these stochastic defects, the effect of developer solutions (alkyl chain length of tetraalkylammonium hydroxide) on stochastic defects was investigated. This paper was built on our previous work in which we investigated the dissolution dynamics of three types of typical EUV photoresist processed in developer solutions with different alkyl chain lengths. Using the same materials, we found from EUV patterning experiments focusing on contact hole (CH) patterns that the long-alkyl-chain developer solution, i.e., tetrabutylammonium hydroxide, was effective in mitigating stochastic defects in acryl-type and hybrid-type photoresists (the latter being more commonly utilized for EUVL).

“…[25][26][27] The dispersion of acid diffusion length during post-exposure baking 26,28) and photoresist dissolution dynamics during the development process have also been reported to have a significant effect. [29][30][31][32][33][34][35][36][37][38][39] This paper focuses on the photoresist dissolution or development process. This work builds on the previous work which investigated the dissolution dynamics of typical EUV photoresist when being processed in developer solutions of different alkyl chain lengths.…”

Section: Introductionmentioning

confidence: 99%

Photoresist stochastic defect generation depending on alkyl chain length and concentration of tetraalkylammonium hydroxide in alkali aqueous developer

Harumoto¹,

Santos²,

Santillan³

et al. 2023

Self Cite

The effects of photoresist dissolution on randomly occurring (“stochastic”) pattern defects in extreme ultraviolet (EUV) lithography were investigated. Specifically, the effects of the alkali concentration of two developers of different alkyl chain lengths; tetramethylammonium hydroxide (TMAH) and tetrabutylammonium hydroxide (TBAH) on stochastic defect generation were investigated for two typical EUV photoresist. In the case of the PHS-type photoresist, results show that stochastic defect generation was almost the same regardless of developer type, given the same developer concentration. For the hybrid-type photoresist, a decrease in stochastic defects was found with the application of the longer alkyl chain length TBAH developer. Results also suggest the existence of an optimum developer concentration. Such optimum developer concentration is considered to be affected by the balance between polarity and non-polarity of the photoresist and developer components.