A method of characterizing and simulating spun-on resist coating contours is described. A low-pass frequency filter is applied to the uncoated contour (topography). Two parameters, P. and a, describe the low-pass frequency filters that estimate the coating contours of different spun-on solutions. The frequency filter parameters are derived solely from step-height measurements of coated isolated-line features. Radial flow-induced coating anomalies are also discussed. These anomalies produce different coating contours for features at different orientations and positions with respect to the centrifugal center of the substrate. A simulated coating contour on a three-dimensional device structure is presented to show the typical thickness changes produced by spun-on positive resist films. A correction for film shrinkage is sometimes required for this simulation procedure.
L. K. White,
"The Characterization And Simulation Of Spin-Coated Resist Contours", Proc. SPIE 0539, Advances in Resist Technology and Processing II, (18 April 1985); doi: 10.1117/12.947811; https://doi.org/10.1117/12.947811