Potential Cause of Inhomogeneous Acid Distribution in Chemically Amplified Resists for Post Optical Lithography

Abstract

The quantum defect method, generalised to the spin-orbit coupling scheme, has been used to calculate the oscillator strengths of the principal series for atomic caesium, taking into account the core polarisation produced by the valence electron. The good agreement obtained with respect to experimentally measured values has led us to carry out new calculations of generalised two-photon ionisation cross sections for the atomic caesium 6s ground state with linearly and circularly polarised incident radiation in the deep minimum region, related to destructive interferences, near the intermediate 7P resonance. A theoretical method previously developed was used; excellent agreement was obtained with respect to recent experimental data. The degree of spin polarisation of the ejected electrons has been calculated in the same region of incident photon energy.

Theoretical Study of Ionization of Polymers for EUV Resist

“…Less electrons on oxgen atom makes radical cations of polymer unstable, or large energy barrier. The results obtained here will lead to the decrease of acid yield, which coincides with the fact that the protecting group decreases the acid yield [17][18][19][20]. Figure 17 shows the energy barrier of poly(methacrylic acid) polymers of protecting group which has the tertiary carbon atom.…”

Study on resist performance of chemically amplified molecular resists based on cyclic oligomers

“…Also, the dependence of acid generation efficiency on protection ratio of hydroxyl groups in the ionization channel was investigated and it has clarified that the selection of protecting groups is important for the acid generation efficiency. 26 Especially, it has been reported that the acid yield of polyhydroxystyrene (PHS) protected by AD gradually increases with increasing protection ratio of hydroxyl groups 27 and that the radical cation of adamantane has comparable acidity to mineral acids. 28 Therefore, a radical cation of AD seems to produce a proton and a radical cation of adamantane.…”

Relationship between Absorption Coefficient and Line Edge Roughness of Chemically Amplified Resists Used for Extreme Ultraviolet Lithography

“…Although the deprotonation efficiency depends on the molecular structures of the protecting groups, the deprotonation efficiency of the protected units was set to a typical value of 0.3. [36] The preneutralization of acids before postexposure baking (PEB) [37] was assumed because annealing-type resists are generally used in EUV lithography. Using the acid distribution after the preneutralization as a boundary condition, the subsequent reaction diffusion was calculated using the reaction-diffusion equations.…”