Assessment and Extendibility of Chemically Amplified Resists for Extreme Ultraviolet Lithography: Consideration of Nanolithography beyond 22 nm Half-Pitch

Abstract

The major resist properties, namely, resolution, line edge roughness (LER), and sensitivity have trade-off relationships. The relationships among them are determined by the pattern formation efficiency. Because of these trade-off relationships, the assessment of resist performance has been a difficult task. The extraction of parameters associated with pattern formation efficiency is important for the proper assessment of resist materials. In this study, we improved the resist model and analysis procedure for the parameter extraction and assessed state-of-the-art extreme ultraviolet (EUV) resists. Using extracted parameters, we evaluated the expected resist performance upon exposure to a next-generation exposure tool with high numerical aperture (NA). Furthermore, assuming the technical limits of resist materials, the extendibility of chemically amplified resists was examined. It was found that the resist requirements (10 mJ cm À2 sensitivity and 1 nm LER) for the 16 nm node are achievable at NA ¼ 0:35, although they were comparable to the assumed technical limit. #

Requirement for Suppression of Line Width Roughness in Fabrication of Line-and-Space Patterns with 7 nm Quarter-Pitch Using Electron Beam Lithography with Chemically Amplified Resist Process

“…D acid was assumed to be 1 nm , for simplicity. Note that the acid diffusion constants of current high-performance resists have been evaluated to be 2−10 nm 2 s -1 [22][23][24][25][26]. D q was assumed to be 0 nm .…”

Relationship between Absorption Coefficient and Line Edge Roughness of Chemically Amplified Resists Used for Extreme Ultraviolet Lithography

“…[38] The effective reaction radii for neutralization and deprotection were set to typical values of 0.5 and 0.1 nm, respectively. [23][24][25][26] LER was evaluated using [23] dx dm…”

“…The proportionality constant f LER of state-of-the-art chemically amplified resists has been estimated to be 0.17-0.31. [23][24][25][26] Other details of the reaction mechanisms and parameters have been described in ref. 39.…”

“…The physical parameters that determine resist pattern formation have been investigated for the latest high-performance chemically amplified resists using the small-field exposure tool (SFET) of Selete. [23][24][25][26][27] LER of the high-absorption resists was estimated by applying these experimental parameters to a simulation based on the sensitization and reaction mechanisms of chemically amplified EUV resists. The dependence of the relationship between LER and absorption coefficient on pattern size, acid generator concentration, and exposure dose is discussed.…”

Resist Materials and Processes for Extreme Ultraviolet Lithography

“…By increasing the absorption coefficient to 10 m À1 , the quantum efficiency to 4, and the effective reaction radius to 0.5 nm, it has been reported that the requirements for the 16 nm node (10 mJ cm À2 sensitivity, 1 nm LER) are achievable using an exposure tool with a numerical aperture (NA) of 0.35. 27) …”