Analysis of dissolution kinetics of narrow polydispersity poly(4-hydroxystyrene) in alkaline aqueous solution using machine learning

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With the sharpening of optical images, the capability of resist materials has become a serious concern in lithography. The dissolution of a resist polymer is key to the realization of ultrafine patterning. However, the details of the dissolution of resist polymers remain unclarified. In this study, the relationships of surface free energy with swelling and dissolution kinetics were investigated using poly(4-hydroxystyrene) (PHS) film with triphenylsulfonium-nonaflate (TPS-nf). Developers were water and 2.38 wt% tetramethylammonium hydroxide (TMAH) aqueous solution. PHS and TPS-nf are a typical backbone polymer (a dissolution agent) and a typical acid generator of chemically amplified resists, respectively. The water intake and dissolution of PHS film with TPS-nf became fast with increasing UV exposure dose. It was found that the increase in the polar components (particularly, the hydrogen bonding component) and the decrease in the dispersion component of surface free energy underlie the fast water intake and dissolution.

Section: Introductionmentioning

confidence: 99%

Relationship between surface free energy and development process (swelling and dissolution kinetics) of poly(4-hydroxystyrene) film in water and 2.38 wt% tetramethylammonium hydroxide aqueous solution

Ito¹,

Kozawa²

2021

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“…The development processes of resist films have been widely investigated by various methods, such as visible and infrared reflectance spectroscopy, 13) a quartz crystal microbalance (QCM) method, [13][14][15][16][17][18][19][20] and high-speed atomic force microscopy (AFM). 21) The dissolution is divided into three steps: [13][14][15][16][17][18][19][20] the diffusion of solvent molecules into the polymer bulk and subsequent swelling, the reaction between the polymer and the solvent molecules, and the diffusion of the polymer chain into the solvent bulk.…”

Section: Introductionmentioning

confidence: 99%

Swelling and dissolution kinetics of poly(4-hydroxystyrene) in tetrabutylammonium hydroxide (TBAH) aqueous solutions studied by quartz crystal microbalance (QCM) method—in comparison with tetramethylammonium hydroxide (TMAH) aqueous solutions

Ito¹,

Betsumiya²,

Kozawa³

et al. 2022

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The dissolution (including the formation of a transient swelling layer) of a resist polymer is key to realizing ultrafine patterning. However, the details of the dissolution of resist polymers remain unclarified. In this study, the swelling and dissolution kinetics of poly(4-hydroxystyrene) (PHS) films in tetramethylammonium hydroxide (TMAH) and tetrabutylammonium hydroxide (TBAH) aqueous solutions were investigated by a quartz crystal microbalance (QCM) method. PHS is a typical backbone polymer (a dissolution agent) of chemically amplified resists. The swelling and dissolution kinetics of PHS were observed by changing the protection ratio of the hydroxyl groups of PHS and the alkaline concentration in developers. Not only the dissolution rate but also the mode of dissolution depended on the molecular structure of tetraalkylammonium cations. For polymer matrices with strong hydrogen bond networks such as PHS, the penetration of tetrabutylammonium cations is considered to be strongly suppressed by their long alkyl chains.

“…Although the dissolution kinetics of PHS in TMAH aqueous solution have been investigated, the details of the interaction between PHS and underlayers during development remain unclarified. [32][33][34] The dissolution kinetics near underlayers are discussed for underlayers having different surface free energies.…”

Section: Introductionmentioning

confidence: 99%

Effect of surface free energy of organic underlayer on the dissolution kinetics of poly(4-hydroxystyrene) film in tetramethylammonium hydroxide aqueous developer

Otsuka¹,

Jin²,

Tanaka³

et al. 2022

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Understanding the interaction of resist materials with the underlayers is important for the development of highly resolving resist materials. In this study, the effect of the surface free energy of the organic underlayer on the dissolution kinetics of poly(4-hydroxystyrene) (PHS) film in a tetramethylammonium hydroxide (TMAH) aqueous developer was investigated by the quartz crystal microbalance (QCM) method. By using 0.95 wt% TMAH standard developer, we observed the correlation between the polar component of the surface free energy of the underlayer and the interaction area of the QCM chart (impedance) near the end of PHS dissolution. The interaction area was defined by the product of impedance change and time. The interaction of the hydroxyl groups of PHS with the underlayer increased with the polar component of the surface free energy of the underlayer. The analytical method developed in this study is useful for the investigation of the resist-underlayer interaction during development.