Classification of dissolution modes of partially protected poly(4-hydroxystyrene) in tetraalkylammonium hydroxide aqueous solutions

Abstract

The development of high-numerical aperture exposure tools for extreme ultraviolet lithography is in progress. The development process (the dissolution of resist films) is the key to fine patterning. The dissolution dynamics of acidic polymers (the backbone polymers of chemically amplified resists) depends on various parameters related to molecular structures. In this study, the dissolution dynamics in tetraalkylammonium hydroxide (TAAH) aqueous solutions was classified into six classes on the basis of the frequency and impedance changes observed during the development process by a quartz crystal microbalance method. The relationship between class and physical parameters of materials was analyzed by decision tree and support vector machine methods. The feature values used were the alkyl chain length, molecular weight, and concentration of TAAH; the viscosity of the developer; and the protection ratio, molecular weight, contact angle, surface free energies of polymers, and film thickness. The classification accuracy was 0.80 for the validation data.

Dissolution dynamics of poly(4-hydroxystyrene) partially protected with t-butoxycarbonyl group in alkyltrimethylammonium hydroxide aqueous developers

“…Owing to the introduction of t-Boc groups into PHS, the dispersion (nonpolar) component (one type of component in surface free energy) of PHS increased. 34) The elongation of one of the side chains is considered beneficial for the penetration of the developer into films and the separation of nonpolar molecular interactions among 30% t-Boc PHS molecules.…”

Sensitization of polymethacrylate resist with adding acid-generating promoters upon exposure to EUV light

“…In particular, the dissolution properties of polymers in developer solutions have been studied extensively. Thus far, the dissolution properties of KrF, 43,46) ArF, [46][47][48] EB resists, 49,50) and EUV resists and model polymers [51][52][53][54][55][56][57][58] during development have been studied with the advancement of lithographic technology. The resist sensitivity can be determined from whether the initial film elutes into the developer or remains undissolved in the development process when the exposure dose is changed.…”

Dissolution dynamics of poly(4-hydroxystyrene-co-methacrylic acid) in tetraalkylammonium hydroxide aqueous solutions

“…As an alternative developer for the positive tone imaging of chemically amplified resists, tatraalkylammonium hydroxide (TAAH), such as tetrabuthylammonium hydroxide (TBAH), has been investigated. [8][9][10][11][12][13][14][15] The acidic polymers have been used as backbone polymers (dissolution agents in alkaline aqueous solution) of chemically amplified resists. 16) For poly(4-hydroxystyrene) (PHS), not only have the effects of TAAH developers on the lithographic performance been investigated but also the fundamentals in dissolution dynamics.…”

“…12,14) In this study, such a change in dissolution kinetics is called the dissolution mode change. The TAAH concentration, 12,14,15) the protection ratio of the hydroxyl groups of PHS, 12,14,15) the decomposition of acid generators dispersed in PHS films, 13,17) the molecular weight, 18) the polydispersity, 19) the electrostatic interaction, 20) and the interaction of PHS with the underlayer 21) have been investigated from the viewpoint of their effects on the PHS dissolution kinetics.…”