Depth-Of-Focus Enhancement Using High Refractive Index Layer on the Imaging Layer
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
This article relates generally to photoresist systems and more particularly to the use of a polymeric overlayer formed on a resist layer which has an index of refraction greater than that of air. The use of a high refractive index, thin film overcoated on a partially planarized resist imaging layer improves the effective depth of focus without deteriorating the resist image. The effective increase in depth of focus is shown to be a function of the flatness variation of the top of a resist imaging layer and the refractive index of the Depth-of-Focus Enhancement (DOFE) layer. The DOFE layer is preferably of the highest possible refractive index.