Y. Y. LEE, L. YU, F. E. H. TAY, C. ILIESCU
Characterization of Spray Coating Photoresist for MEMS Applications

Abstract.
In this paper, we present a practical optimization approach for photoresist mix. A reliable method to qualify the photoresist coating is discussed, not only on the planar surface, but also at the edges and side of slopes within the trenches. By observing the cross sectional profile of the trenches, the spray coater machine and photoresist compositions are optimized to produce a desirable cross-sectional profile, especially for sidewall. Information regarding the uniformity of the photoresist coated along the sidewalls and limitations of the proposed technique are discussed. After optimization, good coverage and uniformity of photoresist are achieved not only on planar surface, but also in sidewall of trenches.

Keywords: Photoresist, spray coating, high topography surface.