Reaction Front Induced Roughness in Chemically Amplified Photoresists

Published

August 1, 2002

Author(s)

Vivek Prabhu, Ronald L. Jones, Eric K. Lin, Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, Christopher Soles, Wen-Li Wu, D L. Goldfarb, M Angelopoulos

Abstract

We have examined, with tapping mode atomic force microscopy(AFM), the effect of post-exposure bake times and developer on surface roughness using model bilayer interfaces of deuterium-labeled poly(tert-butyloxycarbonyloxy styrene) and poly(hydroxystyrene). The AFM results demonstrate the evolution of the resulting surface morphology, representative of a line edge, as the width of the deprotection front increases. As bake time increases, the average surface roughness increases from (1 to 4-5) nm, however the surfaces are not laterally homogeneous. Initially, the bilayer is smooth with residual particulates remaining from the developing stage. After short bake times, the surface possesses a dual morphology with deep pits within a shallow variable topology. The variable topology is characteristic of developed surfaces in uniformly deprotected films, independent of the level of deprotection. A histogram of depth analysis of the AFM images demonstrates that as the width of the deprotection profile increases, the profile broadens asymmetrically, producing a bimodal distribution. However, at long bake times, the overall width of the distribution has doubled the initial, unbaked, roughness and recovered a symmetrical shape. The images demonstrate that the deprotection front is spatially inhomogeneous during short bake times and evolves into a homogeneous broad front. The origin of the spatial inhomogeneity and the dual morphology are still unknown.

Citation

Polymeric Materials: Science & Engineering

Volume

87

Pub Type

Journals

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Keywords

atomic force microscopy, photoresist, reaction front, roughness

Citation

Prabhu, V. , Jones, R. , Lin, E. , Lenhart, J. , Soles, C. , Wu, W. , Goldfarb, D. and Angelopoulos, M. (2002), Reaction Front Induced Roughness in Chemically Amplified Photoresists, Polymeric Materials: Science & Engineering, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=852008 (Accessed October 10, 2025)