Depth profile and line-edge roughness of partially O-1-ethoxyethylated low molecular weight amorphous polyphenol and poly(p-hydroxystyrene) base resists for electron-beam lithography

• Published in: Polymers for advanced technologies Vol. 17; no. 2; pp. 116 - 121
• Main Authors: Hirayama, Taku, Shiono, Daiju, Onodera, Junichi, Yamaguchi, Atsuko, Fukuda, Hiroshi
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.02.2006
• Subjects: electron beam irradiation; line-edge roughness; lithography; low molecular weight; photoresists
• ISSN: 1042-7147; 1099-1581
• DOI: 10.1002/pat.670

The line‐edge roughness (LER) of the chemically amplified positive‐tone electron‐beam (EB) resist based on low molecular weight polyphenol, partially O‐1‐ethoxyethylated 4,4′‐methylenebis [2‐[di(2‐methyl‐4‐hydroxy‐5‐cyclohexylphenyl)]methyl]phenol (3M6C‐MBSA‐EE), and poly(p‐hydroxystyrene) (PHS‐EE) as reference were compared. Phenol groups of these materials were partially protected by 1‐ethoxyethyl (EE) groups to control the dissolution rate for an aqueous alkaline developer. In order to confirm the film homogeneity, the film depth profiles by time‐of‐flight secondary ion mass spectometry (TOS‐SIMS) measurement were investigated. From these results, the films of 3M6C‐MBSA‐EE and PHS‐EE base resist showed relatively flat depth profiles for species originating from the resist components and were suggested to be homogeneous. For the LER analysis aspect, the LER values estimated by using the Fourier amplitude spectra were 5.1 and 7.4 nm for 3M6C‐MBSA‐EE and PHS‐EE base resist, respectively. The former resist also represented the suppressed amplitude A(f) value of the Fourier amplitude spectra in the lower frequency region below 10 µm−1. 3M6C‐MBSA‐EE with suppressed polydispersity and dissolution rate distribution would be a hopeful material to control the LER. Also, it was confirmed that the formulation‐modified resist with 3M6C‐MBSA‐EE showed the lower LER value and remarkably depressed A(f) value than the high‐resolution EB resist which was formulated with p‐hydroxystyrene and acrylate derivative copolymer. Copyright © 2006 John Wiley & Sons, Ltd.