Optimization of spray coating photoresist for high topography surfaces

In this paper, we present a practical optimization approach for photoresist mix and a reliable method to qualify the photoresist coated, 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.