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Proceedings Paper

Mechanism of resist heating effect in chemically amplified resist
Author(s): Y. Ikari; K. Okamoto; N. Maeda; A. Konda; T. Kozawa; T. Tamura
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Paper Abstract

The photo-mask in lithographic process of semiconductor device has an important role to transfer the downsized target image to the wafer. Due to the development of information society, demand for semiconductor devices has been growing. In order to increase photo-mask manufacturing throughput, the current density of electron beam (EB) has been getting higher. EB exposure increases the resist temperature on mask substrate inhomogeneous depending on its current density, shot size, writing order and etc. It is known that the resist sensitivity increases with irradiated resist temperature (heating effect). So, inhomogeneous temperature increase of resist on mask substrate disturbs precise pattern formation. However, the physical or chemical mechanism of heating effect has been still unknown. Here, we examined temperature dependence of acid generation process in chemically amplified resists (CARs). Poly(4- hydroxystyrene) (PHS) and poly(4-[(tert-butoxycarbonyl)oxy]styrene-co-4-hydroxystyrene) (PTBSHS) were used as CAR resin. Monte Carlo simulation moving thermalized electron under the electric field between polymer radical cations were performed with changing the temperature. From the simulation, it was revealed that the energy increase of thermalized electron contributes to the acid yield by 0.038 %/K. Quantification of the acid yields in resist films upon exposed to EB were performed with changing the temperature by titration method using Coumarin 6 (C6) as an acid sensitive dye. The acid yield increased by 0.14 %/K in PHS film and 0.21 %/K in PTBSHS film, respectively. Both values were higher than the simulation value (0.038 %/K). Pulse radiolysis experiment was also performed to observe deprotonation of polymer radical cations at 298 and 343 K. The decay of dimer radical cation of PTBSHS became 1.6 times faster at 343 K than that at 298 K. From the results, it is suggested that the heating effect mainly caused by the temperature dependence of deprotonation rate from the radical cations of PTBSHS.

Paper Details

Date Published: 23 March 2020
PDF: 6 pages
Proc. SPIE 11326, Advances in Patterning Materials and Processes XXXVII, 113260G (23 March 2020);
Show Author Affiliations
Y. Ikari, Osaka Univ. (Japan)
K. Okamoto, Osaka Univ. (Japan)
N. Maeda, Osaka Univ. (Japan)
A. Konda, Osaka Univ. (Japan)
T. Kozawa, Osaka Univ. (Japan)
T. Tamura, NuFlare Technology, Inc. (Japan)


Published in SPIE Proceedings Vol. 11326:
Advances in Patterning Materials and Processes XXXVII
Roel Gronheid; Daniel P. Sanders, Editor(s)

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