High-Performance Chain Scissionable Resists for Extreme Ultraviolet Lithography: Discovery of the Photoacid Generator Structure and Mechanism

Extreme ultraviolet (EUV) lithography currently dominates the frontier of semiconductor fabrication. Photoresists must satisfy increasingly strict pattern fidelity requirements to realize the significant enhancements in resolution offered by EUV technology. Traditional chemically amplified resists (CARs) have hit a barrier in the form of the resolution, line edge roughness, and sensitivity trade-off. This has been compounded by a lack of understanding of the chemical mechanism associated with the EUV process. Here, we synthesize a series of novel EUV photoresists based on a self-immolative, acid-labile poly(acetal) system. These systems are shown to be commercially viable under current EUV requirements. Careful study of the resists' degradation pathways has enabled the identification of a remarkable photoacid generator (PAG) that functions as both an acid generator and base quencher, enabling further improvements over previous resists. density functional theory calculations reveal, for the first time, the connection between the PAG activation barrier and resist sensitivity and suggests why attempts to use electron-beam lithography to predict EUV performance have failed.

Automated summary

Extreme ultraviolet (EUV) lithography is currently the dominant technology in semiconductor fabrication, offering significant improvements in resolution. However, traditional chemically amplified resists (CARs) face limitations in resolution, line edge roughness, and sensitivity. A lack of understanding of the chemical mechanism associated with EUV process further hampers progress. In this study, a series of novel EUV photoresists based on a self-immolative, acid-labile poly(acetal) system were synthesized and found to be commercially viable. The study of degradation pathways led to the identification of a remarkable photoacid generator (PAG) that functions as both an acid generator and base quencher, enabling further improvements. Density functional theory calculations revealed the connection between PAG activation barrier, resist sensitivity, and the failure of electron-beam lithography in predicting EUV performance.