Yoshiyuki Kono

Understanding quencher mechanisms by considering photoacid-dissociation equilibrium in chemically amplified resists

The quencher mechanisms in Chemically-Amplified (CA) resists have been investigated. To explain the acid distribution with a variety of acid strengths in the presence of quencher, a new full Acid-Equilibrium-Quencher model (AEQ model) is proposed and examined in solid-model-CA-resist systems. To observe the reactions in the CA resists, real-time Fourier-Transform-Infrared Spectroscopy (FTIR) is employed during post-exposure bake (PEB). The FTIR peaks of the protection groups are detected to measure the reaction kinetics during PEB. The solid-model-CA resists used in this work consist of both a KrF-acetal-type resist with a diazomethane Photo-Acid Generator (PAG) (weaker-photoacid system) and an ArF-ester-type resist with a sulfonium-salt PAG (stronger-photoacid system). The obtained FTIR results are analyzed using conventional Full-Dissociation-Quencher model (FDQ model) and the new AEQ model. The kinetic analysis of the model resists was performed for different quencher loadings. For the weaker-photoacid system, the AEQ model much more accurately predicts the deprotection-reaction kinetics than the FDQ model with the change of quencher content. This suggests the necessity of introduction of the acid-dissociation concept in the case of the weaker photoacid. For the stronger-photoacid system, both the AEQ and conventional FDQ models adequately predict the kinetic results. This shows that the conventional FDQ model is accurate enough to simulate the super-strong photoacid system. Finally, the new AEQ model is introduced in the UC Berkeley STORM resist simulator. Some simulation examples are shown in the paper.

Study of cross-linking reactions in negative-type thick-film resists

This paper describes a study of a cross-linking reaction model for chemically amplified negative-type thick-film resists. Profile simulation is a major technique used to acquire experimental indicators. For this reason, numerous reports address simulation techniques, and many studies have focused in particular on chemically amplified positive-type resists, due to their role as mainstream resist materials used in the production of ICs. However, virtually no research has been performed on the profile simulation of chemically amplified negative-type thick-film resists. We measured the cross-linking reaction of a chemically amplified negative-type thick-film resist and created a new cross-linking reaction model. Our study demonstrates that this new model is more effective for thick-film resists than conventional models.

Study of nano-imprint for sub-100nm patterning by using SU-8 3000NIL resist

SU-8 (Kayaku Microchem Co., Ltd.) provides well-defined resist profiles with high aspect ratios, and is also suitable for use as a permanent resist. SU-8 has been widely used for many years in the MEMS (Micro Electro Mechanical System), IC package (bump, insulator, encapsulation), micro fluid (inkjet, micro reactor, biochips), and optical device (waveguide, optical switch) fields. SU-8 is a chemically amplified negative resist based on epoxy resin. This resist generates a strong acid during exposure, and PEB (Post Exposure Baking) induces the crosslinking reaction of the resin with the acid working as a catalyst to insolubilize the resist. In our study, we sought to investigate the potential application of SU-8 3000NIL, the most commonly used resist for the MEMS process, to imprint lithography. The results we obtained indicate that SU-8 3000NIL can indeed be applied to imprint lithography after optimizing process conditions for imprinting.