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Reaction Front Induced Roughness in Chemically Amplified Photoresists



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


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.
Polymeric Materials: Science & Engineering


atomic force microscopy, photoresist, reaction front, roughness


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], (Accessed July 17, 2024)


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Created July 31, 2002, Updated October 12, 2021