Enhancement of Acid Production in Chemically Amplified Resist for Extreme Ultraviolet Lithography

Abstract

The trade-off among sensitivity, resolution, and line edge roughness (LER) is the most serious problem for the realization of extreme ultraviolet (EUV) lithography. A solution to this problem is the enhancement of acid generation efficiency per unit volume. In chemically amplified EUV resists, not the acid generators but the polymer mainly absorbs EUV photons. The secondary electrons generated by EUV absorption sensitize the acid generators. Therefore, an increase in the polymer absorption coefficient is expected to lead to the enhancement of acid production. The incorporation of fluorine atoms is a promising way for the increase in the absorption coefficient of EUV resists. However, fluorinated compounds decrease the acid generation efficiency by interfering with the reaction of acid generators with low-energy electrons. We investigated which effect prevails in acid generation. Using a spectroscopic method, it was confirmed that the incorporation of fluorine atoms leads to an increase in acid generation efficiency per unit volume.