Dissolution Kinetics and PAG Interaction of Phenolic Resins in Chemically Amplified Resists.

It is challenging to implement extreme ultraviolet (EUV) lithography in mass production because of strict requirement for EUV resist materials. Under this circumstances, it is important in EUV resist design to clarify the dissolution behavior of the resist film in the alkaline developer. In particular, the dissolution in exposed areas of resist films is one of the most critical processes. However, the details of the dissolution process of EUV resists have not yet been clarified. In this study, the dissolution of poly(4-hydroxystyrene) (PHS) polymer, which is a model polymer of EUV chemically amplified resists, with and without additives such as acid generators and amines was studied by a quartz crystal microbalance (QCM) method. The effects of the acid generator concentration and the addition of amines on the dissolution behavior of PHS films were investigated by varying the exposure dose with the aim of obtaining a systematic understanding of the effect of each resist component on dissolution. Differences in the experimentally observed dissolution behaviors were associated with the effect of each resist component on dissolution. The decrease in the development rate caused by the addition of an acid generator suggests that the solubility in the developer depends on the concentration of the remaining acid generator and its structure. In particular, the electrostatic interaction between the acid generator and the hydroxyl groups in PHS has a strong effect on the solubility in tetramethylammonium hydroxide (TMAH) developer. It is important in EUV resist design to take into account the concentration of undecomposed acid generator.

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Study on Dissolution Behavior of Poly(4-hydroxystyrene) as Model Polymer of Chemically Amplified Resists for Extreme Ultraviolet Lithography

Mitsuyasu

Yamamoto

Kozawa

2015

“…As certain photochemical acid generators (PACs) are strong dissolution inhibitors of phenolic resins and function like a diazonaphtoquinone (the expsoed area dissolves faster [ 11,17,18]), the effect of PAG addition on the dissolution rate of PNBHFA was investigated. Di-4-t-butyl-diphenyliodonium perfluorooctanesulfonate (IPFOS) was added at 4 wt% to PNBHFA in PGMEA.…”

Section: Blend Resist Characterizationmentioning

confidence: 99%

“…A quartz crystal microbalance (QCM) was used to study the dissolution kinetics of the copolymer films in an aqueous TMAH solution (CD-26) in a fashion similar to the reported procedure [10][11][12]. Contact angles were measured on an AST Products VCA 2500XE video contact angle system using 2µL of filtered deionized water.…”

Section: Measurementsmentioning

confidence: 99%

Fluoropolymers for 157/193 nm Lithography: Chemistry, New Platform, Formulation Strategy, and Lithographic Evaluation.

Itô

Truong

Okazaki

et al. 2002

A copolymer of t-butyl 2-trifluoromethylacrylate (TBTFMA) and norbornene bearing hexafluoroisopropanol (NBHFA) as an acid group, which is prepared by radical copolymerization, is employed in our 157 nm resist. The radical copolymerization of 2-trifluoromethylacrylic monomers with norbornene derivatives has been shown to follow the penultimate model much better than the commonly employed terminal model. These copolymers (containing >50 mol% TBTFMA) are too lipophilic to provide good imaging. Blending a NBHFA homopolymer with an optical density (OD) of 1.7/µm at 157 nm into the copolymers (OD=2.5-2.7/µm) results in increased hydrophilicity and reduced OD (2.2-2.0/µm) and provides high resolution images. A copolymer of TBTFMA with vinyl ethers has been identified as a new platform, which can be prepared facilely by common radical polymerization. Certain vinyl ether copolymers are also compatible with the NBHFA homopolymer and thus blending improves their OD and aqueous base development. Because these fluoropolymers are highly transparent at 193 nm as well, they are evaluated as 157/193 dual wavelength resists.

“…Film thickness was measured on a Tencor alpha-step 2000. A quartz crystal microbalance (QCM) was used to study the dissolution kinetics of polymer films in an aqueous tetramethylammonium 'hydroxide (TMAH) solution (CD-26) in a fashion similar to the reported procedure [18][19][20].…”

Section: Measurementsmentioning

confidence: 99%

Novel Fluoropolymers for Use in 157nm Lithography.

Itô¹,

Wallraff²,

Fender³

et al. 2001

Unexpectedly good UV transmittance at 157 nm of poly(norbornene sulfone) bearing a pendant hexafluoroisopropanol functionality has prompted us to employ this fluoroalcohol as an acid group for the design of chemical amplification resists for use in 157 nm lithography. The backbone structures to which the hexafluoroalcohol group is attached are polynorbornene and polystyrene. Furthermore, our discovery that poly(methyl a-trifluoromethylacrylate) is adequately transparent at 157 nm has led us to incorporate the a-trifluoromethylacrylic unit in the polymer backbone by radical copolymerization with styrenes and norbomenes. Thus, four platforms are currently available to us in preparation of 157 nm resist polymers; 1) all-acrylic, 2) all-norbornene, 3) acrylic-norbomene, and 4) acrylic-styrenic systems.