Evaluation of the change in photoresist sidewall roughness due to electron beam-induced shrinkage using atomic force microscopy

Ryosuke Kizu; Ichiko Misumi; Akiko Hirai; Satoshi Gonda

doi:10.1117/1.JMM.22.4.044002

7 December 2023 Evaluation of the change in photoresist sidewall roughness due to electron beam-induced shrinkage using atomic force microscopy

Ryosuke Kizu, Ichiko Misumi, Akiko Hirai, Satoshi Gonda

Author Affiliations +

Journal of Micro/Nanopatterning, Materials, and Metrology, Vol. 22, Issue 4, 044002 (December 2023). https://doi.org/10.1117/1.JMM.22.4.044002

Abstract

Background

Scanning electron microscopy (SEM) is commonly employed for line edge roughness (LER) measurements; however, achieving high-precision LER measurement of photoresists is difficult through this approach because electron beam (EB) exposure causes shrinkage of materials. Moreover, the differences in the 3D sidewall shape before and after shrinkage have not been investigated in detail.

Aim

Evaluation of the impact of photoresist shrinkage induced by EB exposure on the sidewall roughness of a pattern.

Approach

The shrinkage was observed by measuring a photoresist pattern before and after EB exposure using atomic force microscopy with a tip-tilting technique (tilting-AFM).

Results

EB exposure smoothed the surface roughness, rounded the top corners, and reduced the pattern height. Roughness parameters evaluated via LER analysis showed that with shrinkage, the standard deviation (σ) and roughness exponent (α) decreased, while the correlation length (ξ) increased.

Conclusions

The results show that SEM-based LER measurements may lead to underestimation of σ and α, and the overestimation of ξ because of the effect of EB-induced shrinkage. Overall, we establish a tilting-AFM technique to evaluate the 3D shape of photoresist patterns without EB damage and with high resolution and low noise.

Citation Download Citation

Ryosuke Kizu, Ichiko Misumi, Akiko Hirai, and Satoshi Gonda "Evaluation of the change in photoresist sidewall roughness due to electron beam-induced shrinkage using atomic force microscopy," Journal of Micro/Nanopatterning, Materials, and Metrology 22(4), 044002 (7 December 2023). https://doi.org/10.1117/1.JMM.22.4.044002

Received: 30 August 2023; Accepted: 22 November 2023; Published: 7 December 2023

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