Technique for preparing defect-free spray coated resist film

Up to now some 3-D (three-dimensional) devices have been demonstrated using the spray coating of photoresist. Since the detail of the technical performance is not clear, the spray coating technique is still in its infancy. In this study, a technique for preparing the defect-free spray coated resist film is described. A solvent (thinner) vapor is used to fill the pinhole assisting the resist flow. Since this flow is generated by the surface tension, it degrades the uniformity of the resist film on the cavity by decreasing the thickness at convex corner. The balance between the removing effect of pinholes and the thinning effect at convex corners is examined finding the appropriate condition.