| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 539418 | Microelectronic Engineering | 2014 | 4 Pages |
•A comprehensive aerial image model is developed for 3D UV lithography of SU-8.•Efficient approaches for large scale 3D simulations of SU-8 lithography are presented.•A 3D hash fast marching method is developed to calculate the final development profiles.
Three-dimensional (3D) simulations are useful to optimize the lithography process of thick photoresists, however, less efficient models and etching surface advancement algorithms limits current application of various simulation tools. This paper presents a comprehensive aerial image model based on Fresnel diffraction to simulate the 3D inclined/vertical UV light intensity distribution into the SU-8 with the diffraction, refraction, absorbance and reflection during light transmission efficiently considered simultaneously. The aerial image model are solved by using adaptable element size in x, y and z direction to speed up the calculation. The improved two-dimensional (2D) Dill exposure model, the post exposure bake (PEB) model and the Enhanced Notch model are also extended to three dimensions. Furthermore, a 3D hash fast marching method is developed to calculate the final development profiles with less required memory elements. Thus various large scale 3D simulations of thick SU-8 lithography process can be well implemented, and the simulated development profiles have been verified by experimental results.
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