Effect of photo-acid generator concentration and developer strength on the patterning capabilities of a model EUV photoresist

Abstract

Current extreme ultraviolet (EUV) photoresist materials do not yet meet requirements on exposure-dose sensitivity, line-width roughness (LWR), and resolution. Fundamental studies are required to quantify the trade-offs in materials properties and processing steps for EUV photoresist specific problems such as high photoacid generator (PAG) loadings and the use of very thin films. Furthermore, new processing strategies such as changes in the developer strength and composition may enable increased resolution. In this work, model photoresists are used to investigate the influence of photoacid generator loading and developer strength on EUV lithographically printed images. Measurements of line width roughness and developed line-space patterns were performed and highlight a combined PAG loading and developer strength dependence that reduce LWR in a non-optimized photoresist.