Modeling and simulation of acid generation in anion-bound chemically amplified resists used for extreme ultraviolet lithography

Abstract

Extreme ultraviolet (EUV) lithography is the most promising candidate technique for the high-volume production of semiconductor devices with half-pitches of sub-10 nm. An anion-bound polymer, in which the anion part of onium salts is polymerized, has attracted much attention from the viewpoint of the control of acid diffusion. In this study, we modeled the acid generation processes in the anion-bound chemically amplified resists upon exposure to EUV radiation and developed a Monte Carlo simulation code. Using the developed simulation code, the dependence of the quantum efficiency of acid generation on the concentration of acid generator units was calculated. The calculated quantum efficiencies well agreed with the experimental values with a fitting error of less than 10%. The thermalization distance was considered to be approximately 3 nm. The blur of proton distribution intrinsic to the reaction mechanisms of anion-bound chemically amplified resists was roughly estimated to be 4.5–6.5 nm.

Theoretical study on defect risks of chemically amplified resists used for extreme ultraviolet lithography

“…where w is the electron probability density. r 0 values in PHS, 20) poly(methyl methacrylate) (PMMA), 21) and polymethacrylate with an onium salt as a side chain 22) have been evaluated to be 3.2 ± 0.6, 6 ± 1, and roughly 3 nm, respectively. Using Eq.…”

Acid Quantum Efficiency of Anion-bound Chemically Amplified Resists upon Exposure to Extreme Ultraviolet Radiation

“…In this simulation model, the acid generation efficiency from the electronic excited state was simply assumed to be proportional to the concentration of acid generator units. The other details parameter have been reported elsewhere [1].…”

“…We have investigated the acid generation mechanisms induced in ABP by secondary electrons, considering that the acid generation mechanism is a reason for low sensitivity [22,23]. On the basis of experimental results, we have modeled the proposed acid generation mechanisms of anion-bound resists and developed a simulation code for facilitating the development and improvement of resist materials and processes for EUV lithography [1]. The experimental quantum efficiencies were well reproduced by the developed simulation code.…”

Effect of thermalization distance on stochastic phenomena in 7-nm-half-pitch line-and-space pattern fabrication using chemically amplified extreme ultraviolet resists

“…[15][16][17][18] The themalization distance in model resist polymers has also been investigated. The thermalization distances in poly(4-hydroxystyrene) (PHS), 19) poly(methyl methacrylate) (PMMA), 20) and a methacrylate polymer with an onium salt as a side chain 21) have been evaluated to be 3.2 ± 0.6, 6 ± 1, and roughly 3 nm, respectively. The optimum thermalization distance is approximately 3 nm for the fabrication of 11-nmhalf-pitch line-and-space patterns from the viewpoint of the trade-off relationship between acid yield and resolution blur.…”